Toyota MR-2

1991 Toyota MR-2 Engine   

My MR2 motor will not run above 4500 rpm in any gear it does not die it just dies out. I have checked valve clearance and replaced,dirt. cap and rotor, wires and spark plugs the fuel filter and air filter the cat. is clear. when costing the motor serges but not while pulling. Gene

Gene
have you checked the fuel line? I occasionally see one that is damaged and slightly restricted.
If you can test drive without cat, that would confirm that is not the problem.
Reverse blow through the fuel lines including the bypass line,
Do a fuel pressure test, while running,see if fuel press drops @4500 rpm.
Even there are no check engine light, you might still want to check for codes.

I will check gas line tomorrow, the cat. is empty
the head has had a valve job in last couple years
with new timing belt. I was thinking it might be
the filter on fuel pump in the gas tank ?
It seems to be more touchy when warm. the gas line is only maybe 6' long. it is mid engine the tank is between the seats

Gene

1986 Toyota MR-2 Engine   

Engine is fuel injected, not turbo-charged. 1st trip of the day, (generally 20+ min.s) engine runs rough, -idle all the way up to 4000+ rpm. (Has power, but feels like a cylinder isn't firing.) After letting it sit (off) for 15-20 min.s, engine starts up and runs great. However, longer 1st trips don't lead to smooth running. - It seems to have to be shut-off for a period of time, then re-started to get completely past the rough running.

When the problem is present unplug the fuel injectors one at a time and replace. This will let you know if the problem is isolated to one cylinder or something else causing random misfires. If only one cylinder is dead, check the ohms on each injector and let me know the results. Use Extreme Caution Around Moving Engine Parts.

If this doesn't show anything try blocking off the egr valve when the problem is present. You'll notice immediate results is the egr valve has been hanging open.

Give me an update.

Douglas,
Thanks for the reply!! I'll have to wait overnight to test (It seems once it's gotten warm in a day, it's good all day...).

Made some progress today - but nothing resolved yet.
1. I did the easy thing first, disconnected the ERG valve, plugged the vac. line - started it. Ran fast (fast idle 2000 rpm) - occational skip. (Like once every 2 sec.s) Re-attached the vac line - (which didn't appear to be sending any vac to the ERG)nothing changed.
2. Figured I'd look @ the plugs next (I was avoiding dealing w/the spring clips on the injector plugs). When I pulled the 4th ignition cable, the wire had seperated in the solid plastic extension that extends down to the plug itself. - No real way of telling whether I broke it when removing today - or whether it is my problem. -Won't have a new wire set until tommorrow (Tuesday). All plugs look like they've been firing, though 1 & 4 (the broken wire one) showed more black around the metal thread end - none were fouled.
3. Since I couldn't do anything else, I pulled all the injector plugs, removed the metal spring clips, took ohm readings (Each engine cylinder read 2.5 ohms, the intake manifold (cold??) injector reads 3.4 ohms. With the clips removed, I should be able to quickly un-plug / plug in the individual injectors tommorrow when I get the new wires.
4. I didn't mention it originally, but when the skip first showed up I replaced the dist. cap, rotor and spark plugs - and started adding lots of fuel injector cleaner. -Car has 72k miles for whatever that is worth. Nothing I've done has ever eliminated the miss-fire feeling though - only the "run - stop - run again" thing ever seems to work....