Ok I finally adjusted my TPS and got the car to idle around 900. Its been idling around 1600 since Ive gotten it and running really rich. However after I got it to idle down to 900 the check engine light comes on. Its only on when the idle is around 900. If I adjust the TPS so it idles high the engine light goes off. The only code I pulled is code 12 which I know is normal. I cant seem to pull any other codes. Only code 12 comes up. The car runs fine, but the engine light just bugs me. Also I did disconnect the battery to reset the code and go through the idle relearn process. Anyone know what the deal might be?

BTW: My car is a 1985 firebird with 2.8 Fuel Injected and automatic transmission.

 

Often times with older obd1 stuff you won't see a code for anything short of disconnecting a sensor outright. The checks the ecm goes through are archaic. You may need to replace sensors without ever seeing an error light. The reason you have an error is because the rpm it sees is different than the rpm it's commanding. The richness and high idle look like the ecm thinks the motor's colder than it is. Does the fan come on at the right temperature? Since you've done an idle relearn before verify that the IAC is working properly.

 

Yep the fan cuts on at the correct temp. BTW the car started idling erratically again today and it finally threw a code. Code 34 which is a map sensor signal out of range, low. Do i jsut need a new sensor or is there something I need to adjust. I also adjusted my TPS and its reading .54V now.

 

check the injector resistance

repeat

repeat

repeat

 

Replace it and let me know.

 

Code 34 is MAF... There isn't a MAP on the 85-89 engines. There is a relay bolted to the frame just inside of the passenger's side headlight next to the air cleaner box. Swap it with one of the ones by the brake booster (doesn't matter which, they're all the same). If that doesn't work, remove the sensor and look in the side without the elbow at the orange film inside. The film should be flat. If not, you need a new sensor. :edit: You can also get a can of MAF cleaner at the parts store and try to clean up the film if it IS flat.

Problem with getting new MAF sensors is that the parts store ones don't fit right. That plastic elbow always breaks on installation and then the sensor dies again within a year because there is a break in the air box assembly. And that's if the circuitry inside is built properly... Getting a GM one is best, but they run around $250...

 

Usually the maf's what goes. And x2 on the GM maf.

 

Well I finally have had time to look at my car again today. Been busy with college stuff. I can only work on the car on weekends cause it sits at my parents house and I live on campus. Anyways Im still not sure exactly which relay is for the MAF sensor. Can someone ID it for me in this picture. Also I checked the sensor it looks fine. So I wanna replace the relay first to see how go.

 

The big relay is the MAF relay. I think the others may be for the headlight motor. Don't know, as I've never seen a Bird older than 87 in person. Trace the orange wire from the MAF to find the relay.

 

i have a similar problem but when i unplug the mass air flow i still get reads that it is still connected i have replaced the computer and didnt change that. i would really like some help on this cause i am not out of ideas to try. i have even bought a new mass air flow and that didnt help and the mass air flow relay is workin as well and all the fuses that i can find are good.