I have a 95 z28 and my computer failed on me. A buddy of mine who is a mechanic checked it and told me it was for sure the computer. The thing is i went and got one from a junk yard it did help the car run better but now its throwing codes and it misfires when i punch the gas. I know its not the sensors it shows because i replaced them as soon as i saw the codes so they are new. I went to the chevy dealer and asked if they could reprogram it but they said since it was from a different car that they might not be able to do it. That if it was already in another car that it might not pick up the thing that reprograms it.

 

There's almost zero chance that your PCM is the problem. They usually only go bad due to loss of power during programming. In the 11 years I've been around these cars I've only seen ONE PCM fail under normal operating conditions. EVERY mechanic who tells you that it's the PCM is quick to blame it because it's the least understood component of a typical FI engine. Some simple diagnosis would be able to tell you what the real problem is.

What codes is the new PCM throwing? Just because the sensors are new does not mean that they are automatically ruled out. You need to seriously revive your diagnostics before pointing fingers at random parts.

 

whats with the surge of newbies lately?

 

Well my old computer didnt throw any codes and what it was doing is it wouldnt let the car run past 30 mph. it started shaking the whole car untill i let go of the gas. its a a4 btw. so then he took a look and tested everything and he said that the computer wasnt sending a signal to 4 injectors and thats why it was doing that. so i went and bought a used one from a junk yard and i just went and hooked it up and it let the car run better but now it hesitates and backfires all the time. but not as bad as the other one i can go up 80 miles on the highway aslong as i accelerate slowly. And it throws codes all the time they were the tps sensor, iac valve, and that sensor on the intake elbow. i went and replaced all of them and it didnt change much. SO i was just thinking i needed to tune it or something but the guy said it might not be possible?

 

Put your old one back in and see if it goes back to doing the same thing it did. Then I would throw the scanner on it and start figuring out what is causing it to throw the codes. All of the PCMs can be tuned but you just took a PCM that you have NO idea if it had anything changed in it by the previous owner. Thats a bad move if you dont know that the programming is even stock. I'd love to know how he checked to see that the 4 injectors where not working.

 

well i have no idea how he checked it but thats what he thought was the problem first. The injectors. then later he said that he traced it back to the pcm. I did put the old one back on and for a while it worked great. The car had the power it should but now it idled funny. the rpm guage would shake between 500 and 800 when i stopped at the light but i drove it like that for a while and it was fine when i pressed the gas. but now it started to misfire like it did again before i swapped it out in the first place. Now it drives fine when its cold but starts misfiring when it gets a little warm. Oh and it still doesnt throw any codes. So what i did is put the new one on and i thought getting it tuned would help but i dont know a whole bunch about elecronics

 

Tax season.

 

Have your "mechanic" look for a burnt plug wire and check the cap and rotor. It sounds like its one of these two to me, not the pcm. Unless you've had rodents chewing on your wire harness ...

 

Whats with the surge of elitist lately? I mean seriously this board is made for people to help others and share information. He is asking about something so either answer him or move on. I am sure there was a point you didnt know about something on your car and had to ask...and if someone knew the answer would it be cool for them to act all like an ******* to you because you didnt know something hes known forever?

Just saying.

-Buddy-

 

lmao so true but tax season for me was a fail. child support, rent, and insurance = not to mention gas prices!!!

 

hey, , take a joke and dont take us all that seriously!