I have a 88' Pontiac Firebird 2.8L v6, i changed the air filter, fuel filter, and did a basic tune up, i bought the car with a hard starting problem i changed the TPS as we'll, at first without changing the TPS i had to press the gas pedal to start the car and i mean PRESS untill i got it started, and since i changed it i was geting code 21, 21 high and low TPS voltages i fixed that by raising the TPS to it's maxium, i tried doing the whole .54-.56 thing but it gave me code 21, or 22 and wasn't working out, but it did start right up the first two times and the rest it went back to its old self, and it starts smoother but still needs gas to start'er up, the idle screw has been tampered with, and even with the fixed service engine light, it still hasnt corrected my problem, i also checked the TPS for ohm reading or resistance, i got around 2 for the old joint, and .0,.1, for the new one. im not sure if i need to adjust the RPM's, and then do the TPS to .54 or if it's something different, but if thats the case sometimes when i messed with it i could get my car to fire right up, but the Service light would come on with code 21, it seems like .54-.56 aint cuttin it... any advice? thanks p.s i also have a new battery, alternator, fuses, vacuum hoses, and i check all the wiring harnest for defectes, and read the ecm codes only code 21, and code 22 were flyin.

Try resetting min idle and the IAC. There's a couple articles on here somewhere on how to do it, but I can't find them now. Not trying to be rude especially since this is your first post, but help yourself to the search function. And welcome to the board.

yes, that's the first place i went the search bar, haven't seen any situation similar to mine but i just went out and purchased the IAC valve and poped the old one out to find out the gasket on it was missing, it starts now but the engine wont run at stable at 700 RPM's only at about 1,000 what is the specs for the idle rpms? this aint workin out on .54-.56 volts, i mean it sounds good at 1,000 but sonds like its going to clonk out at 7 weird.

For some reason the min TPS setting is different for just about every TPS sensor, .55volts is just a starting point. Have you verified that the TPS is good?

To adjust the min idle you need to close the IAC by shorting two aldl pins (I forget which- A & B maybe?) Then disconnect the IAC and adjust the idle stop screw until it's idling at 450rpm. Then reconnect the IAC and reset the IAC using a similar proceedure. You'll probably find the articles in the tech articles section.

i brand new TPS is on it's way tommorow but the whole min. idle 450 rpm specs wont work, the car clunks out at 500 and below it seems to run best at 1,000 which i believe is high, i did follow the instructions, ground the two terminals A+B turn ignition to on position, disconnect the IAC Connector, then pull out the ground clip(paper clip) start the engine let it idle to normal op temp, then adjust to tachometer specs, which is stated in the book 450rpm in drive which is working out, 800 rpm in drive works fine and 1,000 in park. idk any advice?