I have a 1991 Trans Am 350 TPI with 71,500 original miles. When you of coarse crank up the car early in the morning or after its been sitting a while and when the oil pressure is near 60 is idles okay. But when it starts getting warmer and the oil pressure drops to about 30 it really has a idle problem. It holds it sort of, but it doesnt die until a few seconds later after it surges a lot bouncing from 600 to 900 rpm. I have to put the car in neutral at every stop i go to, but even then its still bad. It idles at the right speed like 600 or 700 in between that, but it just wont idle steady. So i wouldnt think it would be the IAC value, and i replaced the tps sensor and it seemed to help smooth it some, but its still not idling right. I replaced the coolant temp sensor as well because somebody told me that could cause the problem, but it didnt do anything. When i put the new tps sensor on there it seem to help some. So am i on to something...???? When i picked up the car the emissions were taken out and i still havent taken the egr out since it really doesnt do nuthin since it was connected to the egr. And idk if voltage is an issue because when i replaced the tps and left the car in drive for a lil bit when it seemed to smooth out and idle at 600 with only a little surging the battery gauge would drop below 13 and then back past it and then under and past 13. And the connector to my tps doesnt look that great. Do you think it could be the connector? Or possibly a vacuum leak i havent found, or maybe the IAC? im trying to look at every possible aspect that i can do before just taking it to a garage for them to fix it and be charged a crap load of money.

 

Timing?
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Also might be ur injectors are they new or old? my 91 t/a did the same thing and then one of the injectors crapped out.

 

The previous owner before me put nitrous on the car and he retarded the timing or advanced it i think. Thats all i know, i dont know if he ever reset it like its suppost to. He is a friend of mine i still stay in contact with.

 

thats prob it. lol was it even set up for it? poor 350

 

it had a chip in the computer at the time and he sprayed it 6 times. Then took it off. Ill check into the timing.

 

u got a lazer? if not the shop will. not sure of the cost though.

 

no i dont have a laser, i guess ill have to get a garage to check the timing out for me. I mean no the motor is just perfect accept the stupid idle. It drives like a brand new car. But it does also need new cats. Its got the dual cats on it.

 

why dont we start off simple

take the injector plugs off one by one while its running

if there is no change in the motor then you have a problem with compression spark or fuel

 

Yes, the car was sprayed not more than 6 times. He bought the nitrous kit off of me. Had a friend install it, who does this kinda stuff profesionally. Changed the plugs before the install. It ran hard. Then, he sold the nitrous kit because he needed the money. That's word coming from his best friend

 

only other thing i believe was modified was that my buddy i bought it from put a hypertech chip in the car. Computer maybe ???? I havent driven the car since last night since it rained today and so i checked the cats, i know which are just clogged up to death. Could it be that the cats are so bad that it affects the idle because one person for a muffler shop told me this.

 

i fixed the idle problem. It was the stupid connector to the tps. it was completely shot. Got a new one on there and now she idles perfect. Well theirs another hint to anybody that has an idle problem or a surging problem. I got my over heating problem fixed finally it was the dumb relay switch sensor that controls the fans.