1320 killer

iTrader: (6)

I'm having some issues with my car running real lean in certain areas and then it will go real rich and I have real shitty throttle response. It has some popping sound coming from the passenger side header. I changed the crank position sensor, cam sensor o2 sensors, I have tried to have it tuned by 2 different tuners and they say it is not a tuning issue. I swapped the maf and had the same problem. I alos changed the tps sensor and the iac sensors on the throttle body and still no change. Anyways my question is that someone told me that it could be that I have a bad pcm. I thought that thepcm would eighther go out completely or work great completely I was not aware that a computer and work great in certain areas and shitty in others. Can this happen?

TAQuickness

iTrader: (28)

Not a stupid question. PCM's can suffer a partial failure. Typically, there is an error code DTC associated with this failure indicating the PCM needs replacement.

But, before you replace the PCM, have you checked your spark plugs? Are you sure your injectors are working properly?

Doc

iTrader: (9)

Sounds like an exhaust leak which would cause your symptoms. Not very sexy I know, and not very expensive to repair either. When cold, check the header bolts. You did use OEM gaskets? Were these headers "New" when you installed them? If so you could have some heat seasoning issues-once again check for loose bolts. Describe your exhaust system set up further. Are you using clamps? Y or X, H pipe. Cats? Go ahead and mail me all sensors and anything else that you did not have to replace, they are all fine.

You bet your sweet ***, and most shops will milk you dry before they fix the real problem.

Doc

iTrader: (9)

Oh and forgot one thing, do your headers have the emissions provisions? EGR, AIR? If so, you do have good seals, used good OEM gaskets on them too-more exhaust leak potentials...

1320 killer

iTrader: (6)

Well, thanks for everyones input. but I have a few more questions. I am going to barrow my friends pcm. It is froma 99 z28 just like mine bit it is a 6 speed and mine is a automatic. I want take his computer put it in my car flash my entire tune into it to see if that is the problem. Will his computer work in my car? I have kooks headers and they do not seem to have any leaks my Headers are race style headers and have no EGR, AIR. I used oem gaskets and they also seem to seal pretty well. Is there any other way to check the injectors besides swapping them from side to side to see if it makes a difference?

Doc

iTrader: (9)

With the right software you can perform an injector balance test.

brad8266

iTrader: (23)

Have you been under the valve covers for anything?

1320 killer

iTrader: (6)

Thanks Doc but what software do I need to check the injectors?
Yes, I have been under the valve covers to check for bad rockers or broken springs and they all look to be holding up. I changed the plugs and plug wires also. Still can't figure out the problem.

TAQuickness

iTrader: (28)

I didn't see what type of vehicle you have, but if your car is a 99+ Fbod or C5 then yes, his PCM will work in your vehicle. After you full-flash your tune, remember to perform a crank relearn. You should do the crank relearn when you put the PCM back in your buddies car as well.

1320 killer

iTrader: (6)

O.K. Thanks, Is the crank relearn the same as the case relearn? can a simple case relearn fix the problem that I am haveing? well thsi is what I have been told. Don't know til I try it this evening.

TAQuickness

iTrader: (28)

I believe so. In short, the PCM has a "map" of the reluctor ring on the crank. Any time the relationship between the crank reluctor and PCM changes, i.e. new PCM, new crank sensor, new crank, etc..., the procedure should be performed.

Doc

iTrader: (9)

Sorry to get back to you so late...I have been in the air for what seems like the last 20 hours. So from MIA waiting for my connecting flight to JAX. Injector balance test, CKP relearn and lots of other neat stuff can be done with EFI Live.

1320 killer

iTrader: (6)

Do you know if it can be done using HP tuners? I have a friend that has it and I can barrow it when ever I need it. On a side note I really appreciate all the help and suggestion that everyone is posting.

Frost

iTrader: (45)

Yeah, that's what case learn is in the scanner under VCM Controls

1320 killer

iTrader: (6)

Great, thanks. I will do the case relearn tommorrow and I will post the results here. Thanks again to everyone.