i read out the codes on my 1990 305 TBI 5spd.

here is what i got:

23. Low temperature at manifold air temperature sensor OR
Throttle position sensor error.

32. Fault in barometric pressure sensor circuit OR
Fault in exhaust gas recirculation valve diagnostic switch OR
Fault in electronic vacuum regulator valve


not exactly sure what i am looking at. which one should i start with? i upulled the codes out of a chiltons but i have been told that the codes changed from year to year sometimes. anyone have a link to a list that would allow me to confirm that i have the right ones? i cannot access the tech articles right now for some reason. thx!

 

Here you go
http://www.troublecodes.net/GM/

Its all done by engine type and VIN designation

 

this is the error - does this mean the map sensor is bad or the EGr is bad?

EGR open command did not change the MAP sensor signal. Normal EGR flow should cause slight decrease in manifold vacuum which would change MAP sensor signal.

 

First one sounds like its a bad IAT sensor which is in your air cleaner housing. Eather that or its not plugged in. I would test your egr and seehow that comes out first. Could also be bad vac lines.

 

http://www.autozone.com/servlet/UiBr...3d801c0032.jsp

Knowledge of what these parts do will greatly help you analyze the error. A simple test on the EGR that anyone would tell you is to start the engine, reach under the EGR and gently pull up on the diaphragm. By doing this you are letting exhaust into your intake. The engine should lower in RPM or possibly even die. This will prove that its not clogged by carbon deposits. Thats a good thing, means you dont have to unbolt it and clean it off. Though if you decide to dont use any cleaning agent as they can damage the rubber parts inside of the EGR, dont think you would want to spend 60.00 for a new one. So if that checks out, check the hoses that are connected to this EGR. Make sure they are cracked, broken, I would even remove them one by one and try to blow air through them to make sure there is nothing inside blocking the air passage. If all of this checks out you may want to drive up to Autozone and have one of the more skilled employees there come out to your car with a vacuum pump so that he/she may test the EGR and the solenoid connecting to it. They may be able to check other sensors tied to this problem before you shell out the cash on picking and pulling parts in a trail and error type of troubleshooting method. Hmm.. I think I'll go to autozone to have them test my EGR tomorrow with the hand pump, I'd rather not spend 30.00 on something that I would use once lol.

 

ok thx guys. sounds like a plan. i will look at teh IAT as well. thx for the link!

nevada