Bad pcm?
Thread Starter
Teching In
Joined: Sep 2022
Posts: 26
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Bad pcm? Having some weird issues here. Hoping for some thoughts and some help. I'm helping my son with his GTO 2004. His first car. So, he's quite stoked to say the least! We live in an emissions county unfortunately and he has hi flo cats, but I'm seeing some weird results where we are seeing the I/M monitors keep resetting with Key off. I've read a post on this earlier and stated to suggest to test the pins on 20 and 57. Each are showing constant 12V. Is this a bad PCM if I'm having issues like this? It seems like the memory just keeps erasing/losing.
I have starting issues, and idle doesnt run the best either. The starting to me just seems like a tired solenoid on the starter. I also just bought MPVI3 and have seen strange issues while connecting. Its failed reading a few times. I've had to unplug/plug the cable back in a few times and it would finally read. But, looking through the tune file, it mirrors a stock 2004 from the repository. So, nothing really strange from that. So, I'm able to at least read the tune file. Do I take the chance and try to flash with a stock tune file?
So, my question is, if this is a bad PCM? Can I just purchase a P59 and swap it out? Do, I need to buy/make my own bench harness to load a factory file? Does the VIN number copy over? Apologies for all the inquires as I'm not the most experienced in HP tuners.
Any insights are definitely appreciated!
I have starting issues, and idle doesnt run the best either. The starting to me just seems like a tired solenoid on the starter. I also just bought MPVI3 and have seen strange issues while connecting. Its failed reading a few times. I've had to unplug/plug the cable back in a few times and it would finally read. But, looking through the tune file, it mirrors a stock 2004 from the repository. So, nothing really strange from that. So, I'm able to at least read the tune file. Do I take the chance and try to flash with a stock tune file?
So, my question is, if this is a bad PCM? Can I just purchase a P59 and swap it out? Do, I need to buy/make my own bench harness to load a factory file? Does the VIN number copy over? Apologies for all the inquires as I'm not the most experienced in HP tuners.
Any insights are definitely appreciated!
Having some weird issues here. Hoping for some thoughts and some help. I'm helping my son with his GTO 2004. His first car. So, he's quite stoked to say the least! We live in an emissions county unfortunately and he has hi flo cats, but I'm seeing some weird results where we are seeing the I/M monitors keep resetting with Key off. I've read a post on this earlier and stated to suggest to test the pins on 20 and 57. Each are showing constant 12V. Is this a bad PCM if I'm having issues like this? It seems like the memory just keeps erasing/losing.
I have starting issues, and idle doesnt run the best either. The starting to me just seems like a tired solenoid on the starter. I also just bought MPVI3 and have seen strange issues while connecting. Its failed reading a few times. I've had to unplug/plug the cable back in a few times and it would finally read. But, looking through the tune file, it mirrors a stock 2004 from the repository. So, nothing really strange from that. So, I'm able to at least read the tune file. Do I take the chance and try to flash with a stock tune file?
So, my question is, if this is a bad PCM? Can I just purchase a P59 and swap it out? Do, I need to buy/make my own bench harness to load a factory file? Does the VIN number copy over? Apologies for all the inquires as I'm not the most experienced in HP tuners.
Any insights are definitely appreciated!
I have starting issues, and idle doesnt run the best either. The starting to me just seems like a tired solenoid on the starter. I also just bought MPVI3 and have seen strange issues while connecting. Its failed reading a few times. I've had to unplug/plug the cable back in a few times and it would finally read. But, looking through the tune file, it mirrors a stock 2004 from the repository. So, nothing really strange from that. So, I'm able to at least read the tune file. Do I take the chance and try to flash with a stock tune file?
So, my question is, if this is a bad PCM? Can I just purchase a P59 and swap it out? Do, I need to buy/make my own bench harness to load a factory file? Does the VIN number copy over? Apologies for all the inquires as I'm not the most experienced in HP tuners.
Any insights are definitely appreciated!
Thread Starter
Teching In
Joined: Sep 2022
Posts: 26
Likes: 1
Sorry, but how would I go about that? The pins 20/57 show 12v on each. Which according to my pinout are constant power. So, with Key off there is power on those leads. Which theoretically means there should be power to the PCM with key off correct?
Yes, one should be constant power. The other should be key on.
Thread Starter
Teching In
Joined: Sep 2022
Posts: 26
Likes: 1
Assuming this yes Im sure that is what he is referring to. I used a voltmeter on pins 20/57. Which are the constant power. I don't believe pin 19 has anything to do with the memory. Although, not an expert on it. As this is power on with key on.
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Verdad Gallardo Thread Starter
Teching In
Joined: Sep 2022
Posts: 26
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But, it definitely sounds tired. But, the PCM issues are perplexing to me to say the least. Is it out of the realm for these to fail? I've read its common. Although, not that common. So thats why I'm scratching my head. The car is at the body shop now getting sprayed at the moment. So, I need to replace the mass air as its throwing a code. once done I will have to test the I/M monitors again. If it fails again after key off this go around, I'm thinking it has to be a bad PCM. Which if that is the case, I hear I have to swap service number/HW number like for like. Have VATS disabled and swap it over. Hopefully, it will reconnect? I was looking at flagship one. Is there a cheaper way in doing this? Junkyard PCM? Take the OBD port and build a bench harness? Flash the calibration file over and disable VATS? Or, is it more involved than that?
The problem with swapping p59 computers on a 2004 GTO is that it uses a cable throttle body. Most of the p59 computers do not have the IAC drivers onboard, so you have to find one that was specifically used on a cable throttle instead of DBW. Other than that, it is a simple matter to clone your existing program from one p59 to another. However, these things do not go bad very often at all, so I would check every other possibility first.
Thread Starter
Teching In
Joined: Sep 2022
Posts: 26
Likes: 1
Yea, I've read up. Most have the DBW function and no IAC drivers. So, I would need to find one specifically that has the drivers. I'm not sure what else I can check once I get the vehicle back. It runs, and drives fine. No issues. Slow starting but I'm going to swap the starter out.
I'm hoping once I swap the new mass air meter, all the monitors will set after driving and I can take it to get emissions. But, if I have to key off I'm not so hopeful that the monitors will stay in completed status vs incomplete. I'm not sure what else I can look at here for this issue. Previous posts had something similar, and there were a few folks who said bad PCM. But, I dont believe there ever was a conclusion to the post.
I'm hoping once I swap the new mass air meter, all the monitors will set after driving and I can take it to get emissions. But, if I have to key off I'm not so hopeful that the monitors will stay in completed status vs incomplete. I'm not sure what else I can look at here for this issue. Previous posts had something similar, and there were a few folks who said bad PCM. But, I dont believe there ever was a conclusion to the post.
Just a random thought that you should not follow up on, but I believe setting DTCs to "no error reported" automatically passes readiness monitors. Of course we would never want to see anyone scamming an emissions test.
Thread Starter
Teching In
Joined: Sep 2022
Posts: 26
Likes: 1
Well I certainly did not set codes to "no error reported" while leaving the MIL light checked for years on multiple vehicles, so I could be wrong about it. Maybe it does not make them instantly say "ready".