88 Park ave goes to high idle-wont restart

Have an 88 Park Ave w/ 192000 miles. Engine will start fine cold (until today) run fine for about 5 minutes, then the check engine light would come on. If I stop or go to park, engine is at a high idle. If I shut it off with the engine at high idle, it would not resart until it sat for 6-8 hours. Sometimes after driving awhile, the light would go off and everything was fien. Now it will not start at all, (I shut it off with the engine at high idle.) The code is a 21-TPS sensor, which I changed. also have changed (hang on)- egr valve, iac valve, o2 sensor, cam sensor, crank sensor, coolant temp sensor, swapped ecms with another park ave, tried the same with the mass airflow sensor. have also changed the fuel pressure regulator.

I do have spark, and there is fuel in the fuel rail.

Couple of notes, when the light is on the engine cooling fan does not kick in, air conditioner may shut off as well when the light is on.

any ideas............thank you

Just guessing here - sounds like mechanically, something is sticking. You have been replacing electrical components (sensors). If you are still getting the code 21, then I'd concentrate on the throttle body as the cause. The TPS sensor converts the throttle position into an electical voltage. The code 21 diagnostic is a sanity check and means this voltage is out of range.

Clean the throttle body with carborator cleaner inside and outside. As for the no restart condition, check with your nose for a flooded condition.

Thanks for the suggestion-after a 4 day ordeal in my garage with this tired old buick-it was the ECM. I took an ecm out of an 89 park ave and replaced it with the one from my car and what do you know-the 89 park ave started to act just like mine. :eek7:
Problem solved right.........not yet, I put the now known working ECM in my car, and I still could not get it started. After checking that I had spark on all 6 cylinders, I put a noid light on each injector- a 6.99 test light from autozone. Only injector number 1 was firing fuel the rest were dong nothing :screwy:
The problem, the gap on the crank sensor that I had just replaced in an
effort to solve my wont start problem was off about .010. made a little adjustment to that and away she went.

I believe my original problem with the TPS voltage code MAY have been that the wires to the TPS were out of the shielding and running right next to 100,000 mile+ spark plug wires-I have been told just a slight amount of inductive pick up can cause a problem to the ecm. These wires were disturbed by me last winter when I changed the alternator.

Just a couple notes for those of you like myself that dont do this everyday- start by checking each cylinder for spark, then test to make sure each injector is firing fuel using a noid light or a tester (be careful disconnecting the injector wires), also make sure you have fuel pressure at the fuel rail. Remember the basics: fuel, spark and compression-all done in time-it may save you going on a sensor spending spree like I did! :biggrin: