1998 C5, supercharged, MAF removed and CPU (pcm?) swapped and Speed Density tuned.

During some recent service (new alternator and fuel system issues) the car was unhooked from the battery for a long time and multiple fault codes were cleared. Including a p0102 MAF low frequency.

The car is now misfiring on 4 cylinders.

Would clearing the p0102 code cause it? If so, how long until the code is thrown again by the computer?

If not, any other ideas?

 

What is a CPU swap? Are you saying the PCM was changed to a later version, thus the PCM connectors were repinned/rewired?

 

Yeah I think that was it. It was done almost 20 years ago then sat for a very very long time... so I'm trying to recall what I was told about the car back then.

 

Ok, well clearing a code is not going to cause you running on 4 cylinders. What codes do you have now? You need scanner to read live data to see what's going on. If the engine started misfiring after the work was done, there is a high probability they disturbed/broke something. In that case, they should be troubleshooting the issue.

 

If your "tuner" knew anything he would have turned off any DTC's related to the MAF...as far as one bank possibly misfiring seek out an auto diagnostician...the majority of mechanics whether independent shops or dealerships are just hacks and only guess !!

 

It's still there and they are working on it. I just like to independently research things and thought people here would know


ECS built it almost 2 decades ago. It was setup correctly back then, I just don't have much info on it now. The car sat for a very long time and has had some very rough cranks while coming back to life, so several new codes have been thrown. I knew the MAF had been removed and it happened to have a MAF code. The car is still in the shop (unfortunately not ECS like I would prefer). I like to verify everything myself and in my own research, google lead me astray so I came here to just ask.

 

Google won't help !!...you need someone with gray matter between their ears that know what they're doing !!

 

Sorry, my crystal ball is broken.

 

I mean, you actually did answer my question. That the code doesn't matter and it's likely something else. It was literally just me wondering and trying to research so when they start telling me something, I can trust it.

Not sure if you mean me not having brain matter, or the shop that has it. I am the one asking if the code mattered. I'm sure they will figure it out, I just like to learn... you know, the thing the gray matter is for.

Thanks for both of you being smartasses about it though. Forgot why I never come here..

 

Charles, I meant the shop !!...if you had to take the car to a shop for a diagnosis this Forum unfortunately isn't the place for you to learn !!...it many MANY years of study...you don't learn by "turning" wrenches either...let your shop figure it out.

 

If you can't joke around, the internet is not the place for you.
Let's review though.
You come here with vague information, really don't know squat about what was done to your car 20 years ago. You apparaently had a running car before you took to the shop... and after they changed the alternator and worked on "fuel issues" the car is misfiring on 4 cylinders. You offer no current codes, no live data to review, just a vague problem that could be caused by a dozen different things. .....and we are just supposed to guess what could be wrong so you can learn?

Sorry my crystal ball joke triggered you.....I will avoid your posts in the future.

 

A speed density setup is achieved in the tune by setting the MAF max frequency to 0hz and setting the 3 MAF codes to fail on first error. Then turn the check engine light off.
Those 3 codes are P0101, 2 and 3.
If you turn them off, no error reported, the ecu will never default to speed density.

As for 4 cylinders not running, check the ground bundle at the back of the drivers side head. That connection is the coil grounds. I believe there are at least two maybe 3 wires in that single lug.

Ron

 

This, those codes have to be present in order to be in SD tune. If they clear, it puts you back into MAF tune. You might be looking into catastrophic problems if you drove it hard being in MAF tune.

 

I'll have Fran send your receipts to your email in the morning. As far as the running problem goes, let the tech do his thing, anything else is just a guess. Coil grounds, injectors could be shot from sitting, easy things to diagnose in person

 

See? Every single person partaking here is giving up their free time to aid and guide you. Correctly, I might add. You're welcome. And welcome to the forum as always of course. But check the 'tude next time. That's for the Mustang forum.

Grounds. Grounds. More grounds. And make sure the coil pack connector is fully plugged in. That addresses the common electrical issues. Beyond which, who knows? As has been said, whoever began unraveling this mystery should be the one to finish it because they have a general awareness of the car already. You can always get in line at ECS and see if one of Doug's guys can address it at some point. Though I wager that is an expensive route to take.

Good luck and send pics and vids when it runs!

 

If it's the left side after they messed with the alternator wiring then they should be checking the wiring harness that runs down the left side of the engine since they probably disturbed when doing the alternator wiring. It has been known to short out around the back of the engine or otherwise be damaged.

 

As Lionel stated, check that harness. Wires in the harness can be easily damaged. I know better, but because I was in a hurry, and the alternator is somewhat heavy, I got a bit careless, and the alternator suddenly pivoted and pinched my coolant temp sensor wire in half, because the wire was in the wrong place at the wrong time. OP, there are some really smart guys here trying to help. Rob (C5diag) would never insult you. Lucky131969 is also spot on when given enough info. So are several others. Sometimes some answers can be blunt. The hardest thing to do on any car is to expect someone on the phone, or online, to accurately diagnose an issue. All we can do is suggest. Accurate descriptions are essential. Amazing how many guys on here post there car won't crank. When what it is really doing is cranking and not starting!! RONSSNOVA also provided info that the shop may find helpful. These guys have helped me a LOT thru the years. I have a problem that one of the best known tuners in Michigan hasn't been able to figure out....Yet. These guys have suggested quite a few things, and have helped immensely. I know RONSSNOVA and a few others could fix my car.....IF I could get the car to them. I wish you the best of luck. This is one of the best forums on the internet. Patience is a virtue......