91 Camaro 305 TBI

While driving home the other day my check engine light came on on the freeway.

I got home and immediately started checking for codes and i found the following 3 codes.

Info below from Haynes manual.

Code 23- Manifold Air Temperature Sensor; open circuit or short to ground in the mixture solenoid circuit;defective mixture control solenoid;defective ECM- if the mixture control solenoid is shorted to ground,the ECM may have been damaged

Code 32- EGR System; Restricted vaccum hose to EGR solenoid or valve;poor electrical connection,open or short in circuit;defective EGR solenoid;Defective EGR valve; Defective ECM.

Code 42-Electronic Spark Timing; poor electrical connection, open or short in circuit;defective ignition module;defective ECM
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CODE23 Troubleshooting

Alright so for code 23 im guessing the air temp sensor within the air cleaner went bad? Ive researched that sensor before and most auto part stores around here classify that sensor as being the same as the coolant temp sensor.

Can i use a coolant temp sensor in place of the MATS? Why are they classified the same? are there downsides to not using an original MATS? is it plug and play with the coolant temp sensor?

What are the effects of a bad Manifold air temp sensor?


CODE32 Troubleshooting

A while back a friend of mine removed my EGR valve and cleaned it with transmission fluid. Im not sure if this maybe damaged the valve? but when i press down on it the car still bogs and tries to die, which im guessing is normal no?

Regardless i was planning on buying a new EGR as part of my whole ovehaul on the camaro, but was wondering if there is any sort of method to test the EGR valve?

CODE42 Troubleshooting

Now this im stuck on, the code points me towards the "electronic spark timing"

Ive been having a hard time getting my car timed properly at local shops. I tell them to set it to 0 degrees BTDC and one of two things are happening.

Either the shops around here dont know how to time my thirdgen.. or something is wrong with the EST sensor.

The reason i think the car isnt timed properly is because when im at stop lights the car surges a tiny bit. up and down but not erratically just once or twice but doesnt die. At one point after i got the car timed at one shop the car actually would do that and die, but when i went to another shop and got the timing set to another setting it stopped dying (hasnt died on me since) so im pretty sure its a timing issue.

The car no longer dies but it still surges a bit.

Can that code be thrown because of a bad timing setting? or is it related to the EST sensor that must be disconnected when the timing is set?

Ive read the tech article on the timing attempting to learn to time the car myself but at this point as long as the car isn't dying and it can get me to work i don't really want to mess with it much unless im positive that i know what im doing.


Any input/thoughts on these issues are appreciated.

Thanks for reading

 

You need a proper inlet air sensor. The coolant temp sensor is not the same part.

Take a look at this list:
https://www.thirdgen.org/service-eng...ht-error-codes

32. Fault in barometric pressure sensor circuit OR Fault in exhaust gas recirculation valve diagnostic switch OR Fault in electronic vacuum regulator valve
To the best of my knowledge, TBI doesn't have an EGR valve diagnostic switch or an electronic vacuum regulator valve. It does have a barometric pressure sensor.

Code 42 is set when the EST wire is disconnected to set the timing.

You should be able to have the vehicle scanned to see what the computer is seeing from these sensors. If out of whack, the engine could go into a surge.