I have an 87 camaro with 5.7l. I am getting code 23 (Manifold air temperature sensor) I replaced it but still throwing code. I found out my TPS is not reading correctly and replaced that. checked IAC. Checked voltage to the ECU, dont know what it suppose to be but showing 5v. At a loss . anything else that can it can be? new sensor bad? ECM? any help appreciated. thank you

 

If this were mine to diagnose , first thing I'd do would be to research what resistance the sensor is supposed to have for a given air temperature . Now , I can't remember offhand , but to use an example , let's say the MAT is supposed to read 3K ohms (3000 ohms) at 70 degrees F . An Ohm meter would be used to measure the sensor's two terminals on a nice 70 degree day , and say for instance the ideal 3K Ohms were found . Next thing would be to unplug the connector going into the computer and measure the two contacts the computer is connected to the sensor by . Since I have a wiring diagram handy I can tell you that your 3K ohms would appear across terminals "C 12" which will be a tan wire going into the connector , and "D 2" which will be a black wire . If the proper resistance is measured there , then I would begin to suspect a possible ECM problem . But if the proper resistance was not read across the two connectors , then a wiring harness fault would be indicated . Most wiring harness faults are either at connectors , or at any point where the wire is close to rubbing (chafing) or burning against something (like being melted for being too close to the exhaust manifold , this actually happened to mine)

Don't forget to research the proper ohms per temp ratio and disregard the example ohms we used above to illustrate our troubleshooting technique .

Good luck

 

Yea thats the problem I didnt have that info. Just got a service manual so i can get those specs. Thx.

 

 

Just wanted to says thanks for the help and the info posted. turns out there was a problem in the sub-harness where the connector plugs into MAT. Seem to be all good now