Nissan 300ZX

1994 Nissan 300ZX Ignition System Won't Start  

my 300zx is not starting. won't even turn. solinoid on start won't evn click. Had battery checked out and was told it was good. Replaced starter. still same, won't start

Check fuses, incl underhood. Check neutral safety switch (Auto) or clutch switch (std)

1994 Nissan 300ZX Drive Train / Driveline   

Have a 1994 300zx Twin Turbo 2+2, JDM automatic. Recently replaced all of the injectors, electrical injector plugs and fitted a new alternator. Since getting the work done my car keeps jumping in and out of gear whilst cruising. The revs jump from 2000 to 2500 RPM or vice versa. Its fine at idle and only happens when driving. When revving the car in neutral the revs are perfect so I dont think its the TPS (Throttle Position sensor) besides I replaced that 8 months ago without issue. I also had the gearbox rebuilt last year so not sure where the problem is.
Nissan cant find the issue as its intermittent. Seems to only happen when I drive. I replaced the ECU but the issue is still there. Keeps jumping in and out of gear. Only issue found was a broken injector wire but Ive reconnected it and issue persists. Need help fast. Regards, David (Ireland)

If you have an Automatic Trans there might be a concern with the torque Convertor locking up intermittedly.
I Transmission has warranty, you might want to have them check it.

Thanks for the fast reply. Is there anything on the engine side that could cause the sane issue? Bad sensor etc?

Rare possibility, thays why I recommend scan.

1992 Nissan 300ZX Heating / Cooling System   

Climate control is set to auto. air conditioner works for about 5 minutes, than starts blowing hot air

Climate control is set to auto. air conditioner works for about 5 minutes than the heater turns on

Is the actual heater turning on (hot air) or does the air conditioner simply stop blowing cool air?

You'll need to check to see if the air compressor clutch is disengaging (the center of the compressor will stop spinning).

heater turns on

Conrol head failure is the most common cause, but it takes a Nissan capable scanner to diagnose. You will need to have diagnostics run unless you have the luxury of replacement parts to try (free or inexpensive).

WHAT IS Conrol head failure

The control head is the part that contains the switches (AIR, HEAT, etc) on dash. It is the whole unit with all the switches.

1991 Nissan 300ZX Fuel System Won't Start When starting 

My battery ran down real low, I've left the lights on before and had to get it jumped but tach lights were always bright like it shut off the lights before it got to bad, just would need a jump. But now battery got almost all the way drained or real close to it, I got someone to jump it and charge it enough to get the lights the tach lights back up to optimum and the ignition sounds like its trying to turn over (like there is enough power for it) but doesn't seem like its getting any fuel is it possible that ther fuel injectors aren't working cause the battery was dead and ecu didn't have any power or could it be from the anti- theft system.
thank you
Nicholas

It could possibly be from the anti-theft system. You might look for a valet switch under the dash. Also, check your fuel pump fuse and/or relay. If all else fails, check the wires going into the fuel pump with a test light. You will have to get someone to turn the key on and off for you because the fuel pump will time-out. You may be able to access it under the back seat, if not, check under the car on the back of the fuel tank.

1991 Nissan 300ZX Interior Components Malfunction Happens always Always

My 1991 Nissan 300zx has multiple electrical problems. The airbab light stays on, the antilock brake light flashes, the AC does not function correctly, the cruise control does not work. Can this be cause by a bad body control module?

It may be, but the only the way to test these things is with a scan tool.

What you can do is try disconnecting the negative battery cable for fifteen minutes. This will reset some of the systems and if you are lucky restore function. Also check thoroughly for any weak grounds (clean and tighten as necessary) under-hood.

Since these are all going on at once. How likely it it that they are all related?

This is very likely. Check the grounds as best you can, as a bad ground can often cause numerous problem (remove, clean and reinstall).

1991 Nissan 300ZX Engine   

Hi there,

My 300zx (imported & owned by me for 17 years) has gone a bit strange. it starts OK, runs lumpy, pulling back on occasions and back fireing alot. Exhaust pipes are very black /sooty, and a residue or film of black soot on the rear bumper. The car smells of exhaust & petrol mixed. On 2 occasions recently it got to a point where it would not go down the road very fast, back fireing (loudly) with puffs of grey/white smoke, but within 5 minutes clears and continues to run fast. On most occassions it fills & sounds like it's running on 5 only, but this could be me thinking that, as I started by telling you it ran lumpy. I do not have a handbook, but a red light on the dash has recently shown it's self (not seen at start up in the centre of main cluster of ignition lights)looks like an exhaust box with 4 wavy lines above it, what's does that mean please?

Hello, What is your email address please? I'll send you an article for your review about running problems encountered with the Z car.

Thanks,

Roger

Hi Roger,

My e-mail address is [redacted]

Many thanks

Bob

I emailed the article to you.

Roger

1991 Nissan 300ZX Fuel System   

hard to start in morning. impossible to start in really cold weather until it warms up then starts fine after you finally get it started.but after it sits and gets cold again hard to start .1991 300zx na 5 speed

Fuel injected cars use a fuel enrichment method that performs a similar action as a choke in a carbureted car.To activate it, there is an additional temperatore sensor that reads the coolant temp.
If cold the air/fuel mixture is richer.
If hot the mixture is leaner.
It sounds like the sensor is malfunctioning (common) or the wiring to it is faulty.

i replaced the switch and even bought some contact cleaner and cleaned the connector . still hard to start. could it be some kinda relay

If it cranks over slowly, first test the battery, the starter, and the battery cable connections.
If the starter spins over well,but still hard to start, it might be the coolant temp sensor as previously mentioned.
It will make it difficult to start cold, easier to start warm.

new 750 cca battery . new ends ,still the same. even cleaned connector to temp sensor. i have a after market gauge that reads a/f mix it says its running lean.sounds like driver sides has a miss as well cleaned all connectors and no luck .

Try testing the coolant sensor with an ohm meter to determine the amount of temp change. (not the sensor for the guage)
Do all tests for engine miss, including comp test, plugs, wires and injectors. If you wish, swap suspect injector to another side

1990 Nissan 300ZX Ignition System   

A buddy of mine was replacing an alternator on his 1990 300zx. when finished the car wouldn't start. He came to me for help. I'm a locksmith by trade ive worked on nissan door locks magnetic sweeps. the security light flashes on the dash. so i cycled the key in the door. still flashes. i made a spare key and turn the key in the door to about 2 o'clock position and hold it there and the light goes off on the dash. this works on both doors and trunk lock. but still wont start. security light hsould go off just by unlocking door but wont. can you help. I'm skeptic about this form of solution but am willing to try yall to see if i'm impressed with your response and service. this works out good we'll definetly use you often. thanks. Jason C.

Hi Jason,

Information is a bit sketchy to come by on a 300zx as old as 1990.

There exists a service bulletin that says to ensure the hood switch for the security system is free of problems. When closed the hood may not depress the switch properly or completely.

The bulletin further states that sunlight can warm the hood resulting in enough expansion to disengage the switch.

If you would like a copy I'll need your email address please.

It's a start,

Roger

How are you doing on this one? Please update.

Thanks,

Roger

1989 Nissan 300ZX Drive Train / Driveline Malfunction When driving Always

I HAVE A 1989 NISSAN 300ZX 3.0 TWIN TURBO, I WAS DRIVING IT AND ALL OF A SUDDEN THE CAR SLIPPED OUT OF GEAR AND I WAS GETTING NO RESPONSE FROM THE ACCELERATOR. AT FIRST I THOUGHT IT WAS THE GEARBOX, BUT THEN IF THAT WAS FAULTY I SHOULD BE ABLE TO PUT IT IN FIRST AND DRIVE BUT THAT DOESNT SEEM TO WORK. WHEN I SWITCH THE CAR OFF AND RESTART IT I GET 'DRIVE' TEMPORARILY BEFORE THE PROBLEM REPEATS ITSELF! IM COMPLETELY BAFFELED! ANY IDEAS?

I assume your transmission is equipped with overdrive which has most likely failed. Using low gear, see if the car will move. If it moves in low gear, the overdrive has failed. If it won’t move in low gear, the entire transmission has failed A ruptured spline in the torge converter would cause similer conditions.
I hope this helps

1987 Nissan 300ZX Heating / Cooling System   

I have a 1987 Nissan 300zx Turbo with about 112,000 miles. For a couple of years now the air conditioning/climate control has not worked correctly. First, I heard clicking noises coming from uder the dash followed by a running pump sound outside near the right front side and followed by either no a/c or a/c flowing out of the defrost vent. I have had several techs. look at the car and I have found several vacuum line leaks under the hood but we have not torn out the dash to find any leaks under there. One tech said that the climate control module (where you select temp. up or down) may even be bad and need to be replaced if you can find one. If you select recip. you really hot air even with a/c on. Do you have any suggestions. I love the car and want to fix it. Do you know of any service manuals with possible diagrams if we need to get under the dash?

The factory Nissan ones are good but confusing. The HAYNES $15 ones are specific to your car and have simple, easy to read wiring diagrams, with one page for your heater/ac system.Following a wiring diag is like a road map.
The climate cont module a good poss. Have a wrecker check the 'hotline' for other wrecker avail. or even ebay. good luck, nice car!

Can you give any more help than a factory manual is confusing and Haynes has one page? You haven't been much help so far.

The Haynes manual has a detailed schematic of the heater system, that you have to check each wire and vacuum line to ensure functioning.Since the climate control modules are very difficult to find here at autowreckers, I can only assume that they fail often..

1987 Nissan 300ZX All Part Groups   

I'm trying to restore 87 300ZX 2x2 with T tops. Want to replace weather striping/hood gromits/ rubber switch boots for dome light/alarm in door jams engine and hatch compartments. Are these dealer items only? If not,need names of after market manufactures.

You should be able to find all the parts you need on these two websites
If they do not have what you need, you are still one email or phone call away from the part and they are kind at customer service http://www.zcarsource.com/
http://www.1aauto.com/1A/-/Nissan/300ZX

I hope this helps

1987 Nissan 300ZX All Part Groups   

I have had air conditioning work done on my '87 300ZX, and after a recent job, the volume of air coming out of the vents has been reduced even with the fan speed at the maximum setting.

On rare occasions, the volume of air kicks up to a higher level as before, but only for a few moments.

I have had the car back to the Nissan dealer, and they said that the dash needs to be taken apart to have a closer look at the possible problem, but he wants to charge a minimum of $1k to get at it.

A shop that I trust printed out a schematic of the problem, and they think it is a blower relay switch that might be the cause.

yes I woud more likely replace the blower switch. As you have acess to a schematic, if you can read a wiring diagram, you might want to try a few 'jumper wires' to bypass switch to test. Or pickup the switch or relay at an autowrecker (a cheap way to test)

I think the problem is getting to the switch, which requires the dashboard to be pulled out. Have you ever don that on this model?

Not for over 10 years! Nissan had a saftey recall back when car was new, and replaced quite a few. The $12 Haynes shop manual has good diagrams to ease replacement.

1986 Nissan 300ZX Heating / Cooling System Upgrade Happens always Always

How do I put in a new "Heating Core"?

THis is not a job for the weak of heart. It requires removal of the glove box, dash panel, drop steering wheel, dash cluster, radio, and center console. once you have access to the insides, the heater core is on the right hand side behind the glove box area. good luck it takes a while (8 - 12 hours) to do this job. Al

1986 Nissan 300ZX Heating / Cooling System Failing Happens always Always

1986 300ZX 140,000 miles. I'm only owner. Car has been well maintained.
Air Conditioned failed recently. Very Little or mostly no air flow from vents. No cool air, often warm air when there is flow. Thought maybe freon. Took it to my regular Nissan mechanic. He said air conditioning was vaccum system, they don't make them anymore, no parts available, can't be fixed.
I know the system is broken, but I can't believe it can't be repaired, rebuilt, or replaced.
I love car, only drive couple of miles to work, but I live in Los Angeles, and need air conditioning.
Can you recommend a course of action to find out how it can be fixed? Do you know air conditioning mechanic in Los Angeles area who can assist me?

You should be able to find a repair shop in LA. Good grief, if the vacuum part of the system has failed and dealer parts are discontinued there are salvage parts to restore that part of the system operation.

If the system no longer cools the leak can be found by means of injecting dye into the refrigerant and running it a few days. Then using a black light and watching for the dye to illuminate a bright floresent color. The failed part can be replaced with aftermarket parts from a national auto parts chain store.

If the system has not been converted to the R134a refrigerant, that should be done so you can afford the freon. R-12 freon is no longer made. What is left to sell of R-12 is extremely expensive. One has to have a license to buy it. Anyone can buy R134a at Wal-Mart.

Look in the yellow pages for a shop that specializes in A/C repair. Possibilities can be discussed over the phone.

If the system has a major component failure you should expect to spend $1500-$2000 for repairs

Now is the time to decide Is the car worth it?

Your thoughts?,

Roger

Thanks Roger, I was searching for parts (aftermarket)when I found this Q & A site. I figured if there were enough parts for the 86 air conditioning (and there were plenty) then it was likely that it could be repaired.
The information you gave me is great. Now I know exactly what to ask and expect when I am looking for estimates.
Thanks,
Alex

You are welcome. If you are ready to accept my answer so that I may be paid please click on the OK TO PAY THE MECHANIC button.

Many thanks!

Roger

1986 Nissan 300ZX Engine Hesitating When accelerating Always

While driving home the other day, The motor started missing and would not run after 2000 rpm. It will start and idle but if you try to rev it, it will only go to 2000 rpm and start missing and will not accelerate any more. It is blowing quite a bit of black smoke from the exhaust. It has over 200000 miles and to to best of my knowledge the catilitic converter has never been changed. This problem happened all at once. Nothing prior. Fuel filter was changer about 10 months ago.
Any sugestions where to start?
Thanks
Joe Coover

Black smoke out the exhaust is most often caused by a fuel mixture that is too rich.

Does the check engine light come on while the engine runs?

What engine do you have please? Carbureator or fuel injection?

Please advise,

Roger

I know that black smoke is a rich condition. I,m a aircract mechanic that works for american airlines so that would be a simple fix and question. It is a 1986 300zx non turbo. To the best of my knowledge they are all FI. What I am looking for is a answer like the pressure regulator, fuel temp sesor, or something like that. Or someone that has had this problem before and you have given a fix to. Like said this happened all at once.

Fuel pressure on the '86 Non-Turbo should be approx 30 psi at idle and approx 37 psi at any speed above idle.

If fuel pressure is outside specs, replace the fuel pressure regulator and re-test fuel pressure.

Have you had a chance to test fuel pressure yet?

I'm also wondering about the Cold Start Injector, but first knowing the fuel pressure will guide me.

Thanks,

Roger

Thanks Roger,
I will T-in a fuel pressure gauge in the morning and advise. I did take the fuel line off after the fuel filter, put it in a container and turned on the key for the elect-punp. It would pump out fuel for about 15 seconds and then turn off. Is this normal since it is not connected to the fuel rail? It would not pump again untill I turned the key off and back on.
THANKS
Joe

Yes Joe, When the key is turned to ON the fuel pump relay receives ground to energize from the ECM long enough to pressure up the fuel rail for engine start. Without cycling the ignition key the fuel pump relay won't see ground to energize again until the ECM gets feedback that there is oil pressure. When oil pressure is sensed the fuel pump relay remains grounded for the continuous running of the engine.

Roger

Put in a fuel pressure gauge this A.M. when I turn on the key it has 30 PSI. Starting has 30 psi idle, as you start pushing on gas it will stay at 30 and about 1500 starts running ruff, still 30 and at 2000 the engine will not go any higher and startes surging back and forth still 30 but won't accelerate past 2000 rpm. Goes to 2000 falls back goes back up falls off with peddle to floor. any check for pressure regulator? It just doesn't seem elect to me unless there is some elect componet that will cause this.
THANKS
Joe

No other check for the regulator that I am aware of. Fuel pressure won't go to approx 37 psi any speed above idle....? The trouble chart says that is a "fail" and to replace the fuel pressure regulator and re-test fuel pressure.

Even a flow restriction would not effect pressure other than the time to obtain 37 psi from a 30 psi start.

Weighing all this against what we believe is the behavior of an engine running too rich makes condemning the pressure regulator a bit scary. Non the less, it would be my next move,

Your thoughts?,

Roger

Roger,
I will try anything at this point. Can't even drive the car to a place to have them look at it. guess the pressure regulator is a good place to start. Do these things go out all at once? Is there any check on the E.C.C.S. unit that would give the indication of the pressure regulator out?
THANKS
Joe

My experience with pressure regulators has always been pass/fail. They have a diaphram and/or spring inside with no servicability. If yours is the original the longevity of performance is remarkable and makes a sudden failure believable.

Testing the ECCS would not help here as it just fires the injectors based on sensor feedback that excludes knowing the fuel pressure reading. Thats why you don't get a warning light on the dash to have the engine checked other than an oxygen sensor screwing up, or data of that nature.

This may well not be the only problem, but it is a good start. If it fixes 'all' we will both be impressed. I'm just not seeing a trouble chart path that looks to be the better road at this point.

Roger

instaled a new pressure regulator. no help. still the same problem. With the press gauge in line, the pressure is just about 30 and doesn't change up to 2000 when engine startes to surge and quits. Did notice that the idle is a lot lower that before problem. Before when I started it the rpm would be about1200 before it warmed up. Now it is about 6 to 700 even when cold. If it was on a carb it acts like the acc/pump is bad. If you don't accelerate slow it seams to lag. Is their a chance something could be blocking exhaust? One of the mechanic at work said that when the cat/converter on his Vet went out it did something like my problem. What next?
Thanks

When a cat converter goes bad it tends to block the exhaust more and more as the engine warms up from cold. If believed to be the problem I will simply disconnect the exhaust header pipe and put up with the noise while seeing how acceleration is affected. I have road tested cars with the exhaust disconnected to confirm the converter to be the whole problem.

I'm happy to offer to email or fax the trouble chart I have quoted concerning fuel pressure. The next step reads "After replacement of the regulator, repeat the pressure test. If still incorrect, check the fuel lines for kinks or blockage and replace the pump as necessary." If you would like a copy, please tell me where to send it.

I rely heavily on the amount of fuel pressure specifications call for when making a judgement as to impaired performance issues. 30 psi to a wide open throttle starves the combustion chambers. The injectors would open the correct time span called for by the EECM based on the feedback from the sensors that it monitors. The low volume of fuel delivered due to low pressure won't keep up with demand. In effect, it is running out of gas.

Do you have confidence in the accuracy of your fuel pressure test gauge? How quickly will the fuel pressure build to 30 psi from zero? How long will the fuel rail hold pressure if the engine is not started?

I won't give up, I'm looking for anything that will help.

Roger

Hi Roger,
If you have 30psi at idle and as you accelerate what causes the fuel pressure to go up to 38 psi since it is a elect pump. Is their a siginal sent to the pump to increse the pressure? Since the press regulator was changed and had no differance. What gives the pressure regulator a siginal to open or close? The vacuum line on top, what controls that amount of vacuum? Before changing the reg. when I turned on the key press went to 30 right away. after reg change when I first turned on key it only went to about 15 but as soon as I started the car it went to 30 and stais their untill the 2000 rpm when it starts to fluxuate at that rpm as the engine surges back and forth as it starts to quit

I'm going to have to research for the specific answers to your questions about the control of the fuel pressure regulator.

Auto mechanics schools teach that fuel pressure regulators are controlled by the presence or lack of intake manifold vacuum actuating a diaphram. Pressure is controlled by routing the excess flow produced by the pump back to the tank via a fuel return line.

Electric fuel pumps on automobiles either run or they don't. The max output is always produced. Worn out gears in the pump decreases output as will pump armature bearings that permit binding or locking of the armature.

I believe the original fuel pressure regulator was weak. The max output of the pump is always produced and the fuel pump is still able to produce 30 psi. But I doubt that the flow volume is beyond minimums.

The new pressure regulator installed lets us see that the fuel pressure builds too slowly at "Key On" and will not rise to the 37 psi spec at any speed above idle. The theory built into the trouble chart starts with eliminating the pressure regulator before questioning the pump's output. It bugs me that the role of vacuum to the regulator is not mentioned.

More as I learn specifics. I have a medical appointment that will take my whole morning today. Back as soon as possible.

Roger

Thanks Roger,
I am at a point where I just don't know where to look. Started the car again this A.M. Still the same now even the idle is starting to run ruff.
Thanks again
Joe

I'll try and contact a Nissan Service Dept. Shop Foreman today for his take on this car.

Roger

Joe, While I wait to talk with the man at Nissan...

Do you have a fax number or email address I can send some data to? It is possible to get codes out of your car's computer and I thought you may get some clue that way.

Would you like to try? Where shall I send the info?

Roger

The Nissan Shop Foreman called me back and said that fuel pressure is very critical.

He said the vacuum to the fuel pressure regulator comes from the intake manifold and should be approx 15" at engine idle. When the accelerator is pressed the vacuum supply port is bypassed and vacuum to the regulator goes to near zero. Simply unplugging the vacuum line to the fuel pressure regulator at idle should have the same effect as stepping on the accelerator so far as testing for the change expected in fuel pressure above idle. It should jump to approx 37psi.

He also told me that the EECM actually varies the voltage to the fuel pump at idle to minimize pump whine. He said checking to see what voltage is being delivered to the pump will be good information to know. Further, it was stated that even at idle rpm if you unplug vacuum to the fuel pressure regulator and the EECM has cut down the voltage to the fuel pump, the pressure should still go up to 35-37 psi.

Exhaust restriction was mentioned as a possibility, but came in second to fuel pressure. Disconnecting the exhaust header pipe to see what improvement happens is what your friend was talking about, right?

One last thing to try is to disconnect the Mass Airflow Sensor and see if the engine runs any better. It will not effect a change in fuel pressure but the sensor may be dirty or bad and effect performance.

Roger

Roger
Did some test today and this what I found. First when I turn the key on fuel press goes up to around 36 lbs and then dropes off to around 30. when I disconnect the vacuum line to the press reg with car running press goes up to the 36 to 37 range but when I accelerate same problem hesitation at 2000. Plug the line back in and, goes down to 30 again. So it seams that the pump and regulator are working properly. Next I disconnected the air flow started the car, same at 2000 hesitation, I did notice that the fuel press was 35 even at idle with this disconnected and lines connected to press reg. This normal? With the fuel press acting the way it is supposed to after disconnecting vacuum line from press reg and seeing the 35 to 36 that would lead me to believe that the pump is good???
These were all good checks Roger, wish that it solved the problem. Don't know where to go except jack it up and try to disconnect the cat converter. wish that there was something to test pressure comming out of the exhaust to see if this was the problem.
Thanks
Joe

Joe, see if you can just remove the oxygen sensor from the exhaust for a test. It should provide enough relief to exhaust back pressure that you would notice an improvement were the Cat Converter at fault. Should be less work.

I agree with your assessment that both the fuel pump and pressure regulator test good. The change in fuel pressure when disconnecting the air flow sensor is normal.

Are there any loose clamps on the air inlet tube to the throttle body? Un-metered air can cause performance problems toward the lean fuel mix side of possibilities.

Still thinking,

Roger

Hi Roger,
Well,I guess that it was a nice try with the o2 sensor. But, no differance. It wasn't the easy thing to remove. We have done fuel and exhaust, so I guess the only thing left is elect. Is their any check on the distributor for the crank angle sensor rotor plate or any thing like that. Throttle valve switch,power transistor for ignition signal, coil?
Don't know if it could be any thing like egr valve,vacuum control valve,idle-up solenoid,air reg? just looking for something that might have failed in intake system, But I am thinking that would effect idle more that any thing due to at wide open you have no intake vacuum.
Still at a point that I don't know. Sure glad that the American jets don't have this problem. We would just replace the entire engine and let the shop take care of it.
THANKS Roger
Joe

This one will soon have me in counseling if I don't hit it out of the park soon:)

I had asked you previously if you have an email or fax number I could send info to. Some of the pages I have deal with checking the computer for codes using self diagnostics. They include drawings as to how to turn self diagnostics on and off. Would you be interested in going this route to see if the computer will deal an ace?

Some thoughts about your questions...

The crank angle sensor works or it doesn't. Were this sensor to mess up the engine would not start, or die while running.

The rotor could factor if the distributor bushings were worn out. If this were the case there could be impact damage to the rotor tip and/or the spark plug wire terminals inside the distributor cap. Shoot, there could be a crack in the dist cap, or carbon tracking inside, or even down the side of the spark plugs porcelain body.

A screwed up EGR valve that sticks open will cause a poor idle or stalling at idle. You could pull a vacuum on the EGR valve with a hand pump and see if you can feel it lift off it's seat. Some styles let me put my finger tips through slots in the diaphram housing and push up to see if it effects a warm engine idle adversly. (I wear mechanic's gloves) Testing the EGR control solenoid is as simple as unplugging the vacuum hose from the EGR valve and with the engine running above idle unplug the control solenoid and see if vacuum is contolled as you connect/disconnect the control solenoid.

The idle up valve is supposed to prevent a sudden closed throttle engine stumble from stalling.

The FICD solenoid valve pops the idle up to compensate for the load on the engine when the A/C compressor is turned on.

That brings us down to the power transistor for the coil, or the coil itself. I could believe the coil or coil wire could be breaking down under load. (I doubt the transistor is bad.) I sure wish this engine could be run on a SUN SCOPE or equivelant to watch the secondary ignition performance.

The throttle valve switch I need to learn more about. I'm not clear on if it is a micro-switch actuated on/off by throttle angle, or a position sensor with a milivolt range sweep that follows throttle angle.

The vacuum control valve could be considered "tested" if the EGR vacuum solenoid has vacuum to it when it is tested.

Do you want to try on board self diagnostics?

Please advise,

Roger

Roger,
This thing has got me going also. In my line of work, I don't like having a problem that I can't fix. If you will send it to two places, first my home [redacted] and then to work where I can print it all [redacted] if you have a drawing of the vacuum lines routing like egr valve,egr solenoid, everything thats goes up to the vacuum canister, secondary purge control valve, evaporative emission control canister and all of that. The person that had the car before me had all of those lines off and pluged off and routed here and there but it was no problem before and the car ran fine. Just want to make sure those are connected correctly.
If you will also respond on this when sent i can see and answer.
Thanks again
Joe

OK Joe, I'll scan to email the docs I was referering to and get them on their way to both addresses.

Thanks,

Roger

Joe, I have emailed six pages to you. I pray they are clear copies.

Roger

Hi Roger,
All pages came through OK. I ran out after work and got a Haynes Manual to read codes. Here is what I found. rirst 1 red 2 grn code# 12 air flow meter/circuit.
second 2 red 1 grn code# 21 ignition signal
third 2 red 3 grn code# 23 idle switch circuit
forth 3 red 1 grn code# 31 load signal circuit or ecu.
Let me know what you think that I should do and should I go back and erase the codes? The #21 ignitional signal sounds interesting? I just don't know which one would cause my problem or even if they do.
THANKS Roger for sending all pages.
Joe

Now that you have recorded all the codes go ahead and erase them.

Run the engine again and see which codes come right back. These are called "Hard Codes". When let go awhile without checking and clearing codes they seem to have a domino effect. Not all codes apply to all engines the computer will run.

Lets see which codes come back and we shall proceed starting with the lowest number code first.

Roger

Hi Roger,
cleared the codes and ran again. This is what came up again.
Red Grn
1 2 code 12
2 3 code 23
3 1 code 31

Hope we can get something out of this for a fix.
THANKS
Joe

Thanks, I'll start digging.

Roger

Joe, I've put together what I found on codes 12, 23, and 31 and will fire off an email to the previous addresses you provided.

Let's see what this info will do for your car.

Thanks,

Roger

Roger,
Started doing some of the test. The one for code 23 check throttle valve switch for continuity between terminals 18 and 25. page 2 of 6 shows pulg disconected and numbers 29 30 24 their referance is 18 and 25 which ones are these? I took my fluke and turned it so it would sound for continuity,if that is what they are asking for and no matter how I connect those three pins I get nothing. First check on air flow meter I do get 12 volts and on resistance between c,d and ground I get about 1 ohm of resistance. The throttle valve has got me stoped on my test. Please advise if you can.
THANKS
Joe

Joe, That drawing is confusing (pg 2 of 6). The 200SX Turbo is shown near the top of the page and uses the switch shown with terminals 29 30 24.

At the bottom of the page is your 300ZX Non-Turbo and the illustration is cut off. The arrow from the bottom of the page without a number is pointing to terminal 25 of the switch. we're not looking for continuity here. They ask if either terminal 18 or 25 is shorted to ground. If either have continuity to ground, please replace the switch.

If the switch terminals are passing the short to ground test then next is to continue at step 3. (page 3 of 6) and troubleshoot on down the page.

That cut-off drawing really killed your momentum and for that I apologize. I'll be more attentive to that. I should have caught it in advance.

The 1 ohm resistance measured on the air flow meter c & d to ground is just fine. I'd call that "near zero" anyday. 5 or more ohms would have been a fail.

Long day, hope I've helped you.

Roger

Roger,
Thanks, saw that after I asked you about the pins. Please excuse me for being stupid.
Do have a question about the next check that has me looking over and over.On 3 of 4 50g07599 it showes the ecu with the three plug and checking 31. on 4 of 6 it shows 8 and 17 50F01653- 5 of 6 pins 17 and 8 50F01653- 5 of 6 42378 pin 26- 6 of 6 42382 pins 101 102 104 105 if these are all refering to the ecu then it is 4 different plugs I have three. I guess that I am missing something again??also on the 3 of 4 check for pin 31 didn't realise that the check was with it connected. when unpluged ofcorse it would stop the engine. Had to take a piece of .032 wire and go through back side to get a connection. The probes on my Fluke are not small enough to make contact. So, I guess all of these checks are with them connected,
THANKS Roger
Joe

There are three connectors to the ECU. A 15 pin (page 6 of 6), a 16 pin (page 5 of 6), and finally a 20 pin (page 4 of 6). Your reference to page 3 of 4 translates to the 16 pin connector. The artist drawing is a little different on the two pics but they should be the same connector for the checks on pins 26 and 31.

Yes, these tests are accomplished ECU connected unless directed otherwise as in continuity tests.

Roger

Roger,
On step 3 page 3 of 6 it states turn switch on. Battery volts should be present on the pins 18 and 25. then it states that voltage will change to zero under 900 rpm. Well first step states that there should be voltage with key on. I have none. Then under 900 rpm you will have no voltage. They seem to be two different statements. If you have voltage when you turn key on do you lose voltage when it is under 900 rpm and runing? Is this two different test? At any rate I have NO voltage.
THANKS
Joe

When you turn the ignition ON in this step you want voltage and if you do not get it you are asked to adjust the Idle Switch until you do. The engine is not running so proceed to adjust away looking for battery voltage to show up.

This test speaks to what happens as the throttle valve moves. Does the Throttle Valve Switch turn on at key-on-engine-off (KOEO)? It shouldn't. The idle spec is 650-750 RPM. So, the adjustment is done with the Idle Switch until it does. That should translate to 900 RPM with the engine running. This verifies what is expected were the engine running and lets you control the event with precision.

The idle speed spec calls for 650-750 RPM. Start the engine. Adjust the Idle Switch back down to specs. When the RPM drops below 900 the Throttle Switch voltage goes away and everybody is thrilled.

Better?,

Roger

Joe, I messed up on my last post. I've rewritten it and hope it now makes sense. I was just not thinking correctly.

When you turn the ignition ON in this step you want voltage and if you do not get it you are asked to adjust the Idle Switch until you do. The engine is not running so proceed to adjust away looking for battery voltage to show up.

This test speaks to what happens as the throttle valve moves. Does the Throttle Valve Switch turn on at key-on-engine-off (KOEO)? Yours doesn't. So, the adjustment is done with the Idle Switch until it does. That should index the Idle Switch.

Start the engine. Does it idle at the 650-750 RPM spec? Now that the engine is running the computer should control the Idle Speed. Monitor the Throttle Valve Switch voltage. Tach the engine speed above 900 RPM and let it fall to idle. When the RPMs drop through 900 did the Throttle Valve Switch voltage go away?

That is what we want.

Roger

Hi Roger,
Tried to fly to Phoenix this weekend to visit my parents. With spring brake there was no chance for a standby so the car was put on hold for a little.
This is what I have done. There is voltage at the throttle valve switch when the connector is disconected. The voltage is battery volts at the center connector and no volts at top or bottom. Now with the connector connected where should I be getting volts? Is that the volt check on page 3 of 6 check #3 for the ECCS? If no volts, is this where you adjust the TVS? Could it be possible that the points inside the TVS be bad. Is there a check to see if this is possible?
THANKS
Joe

Check #3, page 3 of 6 takes the voltage reading at the ECU connector terminals as directed. This would involve wire colors BLU/GRN 12 VDC input to the switch and 12 VDC output on the PPL/BLU when the switch is closed.

Looking ahead to check #5 verifies the switch operation to pass/fail the switch itself if check #3 has negative results.

Did I send you a schematic of the EECS Control Module? I'll get one to you today!

Roger

OK Joe, The email link and the fax are finally on the way. I thought my FAX machine was on strike for a while there but it woke right up when I pulled the baseball bat out of the "V" shaped crater I put in the top of it a few minutes ago.

Roger

Hi Roger,

Weather got better so was able to work on the car again. Got the new ECU in and changed it BUT NO change to the problem. Did seem to idle a little better. Also got a air flow meter with it, but haven't installed as of yet, don't think that is the problem but got it with the ECU. Guess the next thing is the TPS. What do you think?
THANKS Roger
Joe

Mercy, I dislike throwing parts at a car until something magic happens. I'm going back over the data to see what I must have missed. I'm like you. I want to diagnose the problem and repair it with minimum outpocket expense. Safety first.

Consequenses are not nearly as critical with automobiles as in aircraft repair, but still lives are at stake. One must be able to accelerate across an intersection without losing power for fear of being T-boned by a speeder... Power to get on the freeway safely.

I served seven years in the USAF as an aircraft mechanic. I well know the responsibility on the ground crew when the aircrew begins the takeoff roll and passes S1 on the runway. I made sure when those wheels came up that I had earned my keep and a clear mind at the end of the day.

You have a different ECU in play. What codes does it store in memory, please?

Roger

Hi Roger,
Yes, aircraft are a little different. You can go into the flight data computer and it will tell all. There are so meny back up systems you don't have a total failure.
Started the car and the codes came out 12 31 23 Cleared got ready to restart again and found that the TPS was unpluged. Pulged back in cleared and got the same codes again. Remember I said that it seem to idle a little better. That was with the TPS unpluged. With it pulged back in it was a little worse. Don't know if that is a help.
Let me know.
THANKS
Joe

I've scheduled my counseling to begin next week. :)

Seriously, do you want me to back out and see if another provider can get you where you need to be?

I'm really trying not to hit the wall but I'm the first to confess I don't know it all. If I have risen to my highest level of incompetence you may have to say "You're Fired!"

Roger

Hi Roger,
You might get us a group rate. I adjusted the TPS today. Where you have it runing and turn the TPS untill you get continuity between the top two post. Still the same. I just don't know Roger. Just about ready to junk the car. This has got me?????????
THANKS
Joe

Hey, at least you didn't "Lawyer up" on me. The group rate is a killer idea!

I thought the switch was adjusted with key-on-engine-off and that after you did this you could start the engine and the idle speed control motor would be "indexed" and take over. I was expecting the idle speed control to be commanded by the ECU to drop the idle back to specs.

Are you in Tulsa,OK?

Roger

Roger,
I am here in Fort Worth Tx. I work at the over haul base at Alliance. We do the 767 and the 777. The check that I did was out of the Haynes manual. Is there another that you know of with key on?
You gave me as much as you could Roger. I would hate to try to fix a aircraft over the net. Don't know of anything to do except take it to the dealer. Don't know if my wallet can take that.
THANKS
Joe

When you had mentioned rain was a factor last weekend and delayed your being able to work on the car I wondered where you are. I'm Northeast of Oklahoma City in Arcadia, OK and we had rain also last weekend. I was guessing you could be in Tulsa.

The Key-on-engine-off (KOEO) test I was referring to was for Step 3 page 3 of 6 to confirm Idle Switch operation.

You can control a car dealer service dept visit by not authorizing more than a diagnostic fee. If you can demonstrate the symptom to the shop foreman and he can duplicate the complaint you should get an effective diagnosis and an estimate for repairs.

Before you do that you should consider having me step aside and see if we have another provider who will read through our dialog and perhaps offer you something that I have not. I won't be offended and I want you happy with this site for information in the future.

It's your call,

Roger

Roger,
One last try. I did check #3 page 3 of 6 Here is what I did. It says to check volts between 20 and 18 what I did was 20 and ground and got 12 volts 18 ground got only 9 volts 16 got 12 again and 25 got .02 volts. When I adjusted the TVS I disconnect plug, started engine (idling), connected two top terminals and rotated switch untill I got continuity and tightened screws back down. This is what the Haynes says to do. Does this sound correct to you? What do you think about other check. LAST TRY before shop.
THANKS
Joe

Joe, The procedure you outlined skips step #4 on page 3 of 6. I'm asking you not to do that until we have the results sought by following the Mitchell 1 Auto Repair path I sent you documented.

I don't have the Haynes Manual so I can't hypothetically blend data found by one method with the expected results the second method should yield and make an accurate assessment. I fear that makes me jump to a wrong decision.

I'm trying not to throw in the towel,

Roger

1986 Nissan 300ZX Fuel System Hesitating Happens sometimes No pattern

I have spent over 400 dollars at a dealership trying to fig this out and changed several parts myself. What happens is when accelerating or driving at a steady speed, the engine will start to hesitate and it will buck when I press the gas. It sputters as it tries to move. It doesn't do it all the time. In fact I went about three weeks without it doing it at all. I thought it was because I didn't warm it up enough because it tended to do it more if I just up and went, but now it seems to do it whenever it feels like it. A lot of times when just idling, the rpms jump back and forth from about 200rpms to 900rpms. Then sometimes it will stall. Sometimes when it is doing this, it will seem to even it self out after a minute and then run fine for a while. Please help, I am a chic who likes to work on her Z, but I'm running out of ideas and money!!! Plus mechanics get grumpy when they have to work on it. Thank you!

Dont know what the dealership did for you for $400 bucks but pull your pocket book out and help themselves.A thourgh diagnostic scan should have been preformed to try and get to the bottom of your problem.They may have preformed one but once the tech got to the first or second solution on the flow chart, he probably stoped and said the problem was cured.Wrong.The flow chart must be followed to its full extent to insure a proper repair.It sounds to me as if that there may be a trottle control sensor or a vaccum leak of some type that may be causing your problem.Try taking it to one of your local parts houses(Auto Zone,Pep Boys etc).Some offer this diagnostic service for free or at a nominal charge.If any codes are retrieved, dont take their word as to the solution but rather ask if they can provide you with the pertenant flow chart or direct you to how you can obtain said chart and walk all the way through it.Its time consuming,thats why most techs stop when they think the problem is solved.
Good Luck,
Paul

it is a 1986 and has no computer diagnostic system.

Sorry I errd in the year of your vehicle.There are some tests that can be preformed on the vehicle via a computerized scanning station.It still sounds to me you are having an air flow problem that may be caused by a leak in the system.You say you have changed several parts yourself.Were any of these the MAF,O2,TPS sensors?You may even look at the catylitic converter.If the proper amout of exhaust is not there it can also cause this type of problem.The converter is full of a ceramic that in time may melt and clog the system.Try a trusted muffler shop(Midas,Meitege etc)to see if this mite be the problem.
Good Luck
Paul

Sounds good. I had a friend check it out and he thinks that it's the tps, so we're changing that. If that doesn't fix it, then I will try the other things you suggested. Thanks for all your help.

If the problem still arises,let me know and we'll try and work through it.
Good Luck,
Paul

1986 Nissan 300ZX Drive Train / Driveline   

I have a little bit of free play at the top of my clutch pedal travel. How much is normal? How do I adjust it to get normal travel?

Normally up to 1 inch is ok. For racing etc, I like to see 1/2". Easily adjusted at the slave cylinder.

I have 1 1/2" to 2". How is the adjustment performed?

On the side of the bellhousing, you will see a small clutch slave cylinder, it has a threaded rod with an adjustment nut on it. Adjust it until freeplay is acceptable.
The 1 1/2 to 2 inches means that the clutch is weraing, my guess about 65% if it has not been adjusted before.

1986 Nissan 300ZX Electrical / Lighting Systems   

Replaced alternator after having it verified as bad at NAPA, now when I start car guages etc do not work until I rev the engine then everything seems to work fine

Sounds like the voltage regulator is not up to par. Get the new Alt tested, under idle and under load conditions

A simple additional test, you can make with engine running.
Put a digital voltmeter on bat terminal on rear of alt' Record the voltage.
check voltage at + batt terminal.
If more than .4 volt difference, you have a bad wire or bad connections.

1986 Nissan 300ZX Engine   

86 300zx 138,000 miles, pull out of parking lot onto street and car cut off. Engine turn over but would not restart. Eventually battery drained and strated to give click noise. Charged battery but then motor would not turn. Had it towed to shop where we were able to get it started by crimping the fuel line. Now engine vibrates and I get white smoke from exhuast. What is the diagnosis.

Hello, White smoke from the tailpipe indicates coolant in the combustion chamber.

One idea is to pull the spark plugs out and see if they are wet. A compression test will identify the cylinders effected if a head gasket has failed.

Roger

I fail to mention the engine vibration. What is the repair and approximate costy?

One would think the engine vibration may be caused by poor compression and cylinder misfire if indeed the head gasket has failed.

Calls to local shops will be more accurate as to repair costs but keep in mind nothing has been verified through diagnosis.

If the head gasket needs replaced other repairs may be needed while the head is off. A valve job may be suggested or the head may need vatted to deep clean oil returns and vacuum ports.

Will you be doing any of the repairs yourself? How would you have me guide you?

Roger

1985 Nissan 300ZX Fuel System Malfunction When starting When cold

Why does my car have major problems starting in the morning when it's cold but after getting it started the first time it starts and runs OK?

This is going to sound crazy but I bet that your low oil pressure switch or your low oil pressure cutout relay are going bad. It works like this... you crank the engine for 6 - 10 seconds then the car starts.. wow.. must be a fuel problem, poor fuel delivery.. something like that.. wrong.. while you are cranking the engine.. the oil pressure builds up closes the contacts and the fuel pump starts pumping fuel.. sound familiar?? So to trouble shoot the problem you shut the engine off.. then attempt to restart and it fires right off.. hmm where is the problem.. easy way to verify this.. with engine cold. loosen the fuel line to the fuel rail or filter... have someone try to start the engine and see if you have instant fuel pressure.. if you do not have them see if the fuel pressure starts upon sight of oil pressure... I am sure this is your problem.. good luck... AL

I'm not so sure this is the problem. In my case It takes me up to 30 minutes of cranking the engine,(obviously not continuously) sitting with key on/engine off, pumping accelerator(I know this shouldn't be necessary but it works). At first the engine just cranks no real sign of firing, then it starts to sputter a little, and when it starts it's almost like it's after I let off the key. I'll give the test a try. if this is the problem where would the switch/relay be located? Also please let me know if you have other thoughts after my comments. Thks Dave

Not exactly sure of location, but go to the parts house and they should also have the location of the relay.. or u can call the dealership, ask parts and should also be able to tell you the location... and all 4 free.. good luck Al
ps.. it sounds like a low oil pressure relay 2 me,

1985 Nissan 300ZX Electrical / Lighting Systems Malfunction Happens always Always

Keeps burning up alternators after about 10 hours use. Have new battery and starter. I apparently purchased the car with the problem. Dash warning lights all light up and the digital charging display drops from about 14 to 12 and then down from there.

There is a "short" of some kind, or the charging control regulator is faulty. If this control is in the computer, then the computer is at fault. What it sounds like is the charging regulator is calling for full recharge for the battery, all of the time. This would eventually fry the alternator.
A new starter is only needed if it won't start the engine, or is drawing excessive current. While a battery can cause alternator problems, have it checked first, before replacement. Due to what you state as a problem, I'd look at the computer first, and or the charging control that regulates the alternator output.
Now, if it is the computer, you are looking at a major expense. I can give you an idea as to how to beat that cost. Find a car that has been totalled, one that is similar to yours. It might be a different model, but still have the same computer. Be sure the computer was not damaged in the crunched car. Buy this car for as low a price as you can, scrap price would be great. Get the computer out, take what else you might need then sell the car for scrap. You'll end up with spare parts, and recoup some of your original cost.

1985 Nissan 300ZX Heating / Cooling System Malfunction Happens always Always

The air blower blows out warm air, mostly out of the defrost, when traveling at higher speeds all the time. When the A/C kicks on, no cold air comes out. The low pressure line coming out of the compressor is cold to the touch, but the line going back into the compressor is hot to the touch. What could be the problem?

The first thing you'll need to do is have the regrigerant level (pressure) checked with A/C gauges. If this is the original air conditioning system and the regrigerant charge is low the regrigerant will need to be recovered and the system vacuum down to test for leaks. Then you'll need to retrofit the system to the new R134 refrigerant, unless in the unlikely event you can find the old R12 in your area.

I retrofitted the system already. It is sealed and has no leaks. Even so, as I stated in the first note, the same conditions exist the same as before I retrofitted the system.

Does the compressor clutch stay engaged when the A/C is on?

Did you have the old refrigerant evacuated with a machine or?

Yes, the clutch stays engaged when the A/C is on; no, the old refrigerant was not evacuated with a machine. I just let it bleed out.

1985 Nissan 300ZX Heating / Cooling System   

THE A/C STOPS COOLING AND THE VENTS CHANGE FROM FACE TO DEFROST UNDER ACCELERATION

Hello, This condition is usually caused by a vacuum leak.

Try to locate the vacuum reservoir. It is a ball shaped container (sometimes a rectangle) with one or two ports for connecting vacuum lines. Are tubes connected to each port?

Look for a broken or collapsed or disconnected vacuum line. Listen while the engine runs for a vacuum leak around the heat/ac mode switch/controls.

If no leak can be found it may be the diaphram in one of the HVAC Case door actuators is weak or leaking.

Roger

Yes I Thought it was a vacuum leak also and checked the reservoir, there are 3 hoses coming off it and I haven't replaced the hoses so that is my next project. I'll see if that works. will let you know

Update me when you get the chance.

Roger