Chev Sprint

1991 Chev Sprint Engine   

My problem car is a 1991 Chevy Sprint. It has a 1.0 L 3 cylinder engine with 5 speed manual transmission. It is not the turbo model. It’s probably up around 220,000 kilometers. At about 175,000, I rebuilt the engine, having the head redone professionally and honing the cylinders and replacing the rings myself. I’m guessing at the numbers above, my son has the car and the records.

I don’t believe the rebuild is any part of the problem. The car ran beautifully for a couple of years after this work was done. It still starts easily in cold weather and when cold. The problem is that it runs very rich. The check engine light comes on, but the only code is for the oxygen sensor. I’ve replaced the sensor several times. After replacement, the car runs great for a day or two, sometimes three and then the problems return and the check engine light comes on again.

The car tends to run pretty good in cold weather and when it hasn’t warmed up yet. It will even continue to run acceptably on a trip that starts with the engine cold, but if you stop for two minutes or so and then try to use the car again, it will generally start OK, but is hard to rev up and has little power. It doesn’t want to idle and you have to coax it into revving up. If you race the engine a bit, it will then go ahead and run, but it runs rough and still has a tendency to die. If it does die, it won’t restart and has to sit a while before you can get it to run again. When you do get it restarted, you can generally drive it, but it doesn’t run well. I’ve been stranded in traffic a couple of times when it has died and won’t restart.

I’ve replaced the O2 sensor, the spark plugs and wires, the air filter, and regularly change the oil and oil filter. I’ve considered changing the fuel filter, but all the indications (black coatings on the entire exhaust system) are that it is running rich, not lean.

Because there is a clear change in behavior between the cold engine and the warm engine, and because the temperature gauge didn’t seem to indicate the engine was warm when it should have been warmed up, we changed the engine temp. sensor. This fixed the temperature readings, but not the behavior.

Occasionally, the car runs great, responsive and lots of power, I suspect the problem is a sensor or the computer, but I don’t know what to do next. To be honest, I haven’t been able to locate the engine control module (computer). It doesn’t seem to be under the dash where I would expect it to be. BTW, this engine has throttle body fuel injection.

I would appreciate any suggestions you can provide.
Thanks,
Mike Weaver

your ecc or computer is in the Front seating area, driver side, under dash, mounted above kick panel.
It would seem to be pretty old and could need replacement.
That would be a good start.
You may also want to check the injection body for gum and build up and clean it out with some scarb cleaner.

OK, The ecc's I've changed in other cars (Chev. Celebrity) have been removable aluminum boxes. I can't find anything like that on the Sprint. Is it located between the steering column and the radio or between the column and the door? Am I looking for an aluminum box? Thanks.

yes it should resemble a silver or black box with a approx of 30 wire connector.

OK, thank you. I gather this is the next step to try. There aren't any other sensors that I've missed that would be cheap and easy to try. Bye, mw

No as a matter of fact there are other sensors that may be bad and mis-reporting to the ECC system.
You have your Map sensor
Intake manifold temp sensor
EGR valve.
You still have the option of running a diagnostc on your ECM before pulling it , you can do this free of charge at auto zone parts store.
This can possibly save you a lot of money.

OK, this is the sort of thing I'm looking for. The intake manifold temp sensor may be the one we replaced. I'll look for an egr valve. Where will the MAP sensor be located on this car?
Unfortunately, the only Auto Zone in Saskatchewan seems to be in North Battleford. That's about an hour and a half away from me in Saskatoon. Would that ECC test be done with an OBDE (sp?) meter or is there something else that is used to test them? Thanks again, information like this is what I was needing.

Yes they will use a ECC scanner just like the one you can purchase.
The thing is this is still a long shot, because if your check engine light did not come on there may not have been a code set.
At other times there could be a code even if the light did not come on.
Either way it is a chance you take , but if there is a code set it will more than likely help to diagnose the problem you are experiencing.
You have a TCAC thermosensor component, Thermostatically controlled air cleaner(TCAC) system, this was replaced with the traditional MAPS later on , this does the job of your TCAC.

The hot idle compensator is mounted in the air cleaner. When the engine room temperature and intake air temperature rise abnormally high, the air/fuel mixture tends to become rich due to the decreased intake air amount, and as a result, the idling becomes unstable.

There is also a three Way solenoid valve (TWSV) it opens its inner valve to transmit vacuum from the intake manifold to the secondary air valve.
When the engine coolant temperature is low, the thermal switch is ON. Then the TWSV receives a signal from the ECM, and opens the valve. Thus the TWSV transmits vacuum to the secondary air valve to opens its valve.

OK, this gives me lots to work on. Thanks for your help. I'll click the OK to finish this next. I'm assuming they'll let me close it in spite of sending this note. Thanks again. :)