westc

I also posted this in the tech/performance area, because I did not know where it went exactly:
I need some help/advice on my car. I do not know a lot about cars or terminology. Also don't know a lot about my car. I have posted on here about this problem months ago; hoping to get some new/updated perspective. My story is lengthy.
I bought my car used out of tamps, Fl. The car had been hit in the front wrecked and rebuilt. All it needed was paint. Drove well, no issues. Brought it home. Has it painted, happy with it except for an issue on idle. The car idles really rough and, at some points, it would actually lie when stopped at a redlight. When the air was off, it wasn't as bad, but with the air on, the idle was really rough. I took it to a local mechanic to check it out and scan it on the computer. The codes it threw were an 02 sensor and the mass airflow. So, he got a new mass airflow (I think from autozone or advance) and put it in the car. Did not help. He checked out the wiring and found nothing. He doesn't really work on or isn't familiar with corvettes, so he recommended someone else. Called him (who owns his own 2002 ZO6 and is familiar) and he looked at it and said it probably needed a tune. He informed me the car has no cats or 02 sensors. I do not know what else has been done to the car. Looking back, I probably shouldn't have bought it given the situation, but I did drive strong, and I've always wanted one. I made an appointment with a tune shop fairly locally and they did an HP Tuners tune. The fixed the idle. It idled fine. The problem was on the way home, when I would accelerate, the car had a terrible hesitation, especially around 2000-2500 RPMs. But it is a consistent problem and is bad enough that the passenger can feel it. So, I turned directly around and took it back to the tuner to address the problem. He drove it and said it was noticeable. The hesitation was not there before the tune. The idle was bad before, but it did not have the miss/hesitation. He kept the car for nearly two moths trying to figure it out. He even took of the tune and did it again and said it didn't help. He, too, checked a lot of the wiring and found nothing. He also tried another MAF and it did not help. He tuned to bypass the 02 sensors if I understood correctly. Eventually I got fed up with the fact that he did not seem to be finding anything, and him being about an hour away, I did not know how much time he was actually spending on it. He did say he thinks the problem is either electrical or in the wiring. So, I took it back to the second mechanic (the one with the Z06) and had him go through the wiring. He found one small portion or wiring that looked burnt up and replaced it, but it did not help and was not the problem. He also got the MAF code, which we told him about. He wanted to try to replace it (a third time) as well, as he said some of the aftermarket ones are junk, He did that, and it did not work. The MAF is the only code the car puts off. So, he found nothing as well. He thought the problem was probably in the original tune. So, I got another recommendation about another tuner fairly local and took him the car. He drove it and said he couldn't be 100% sure, but by driving it, he was fairly certain that the problem was in the tune. He said he could fix it. Well, after the weekend, he called me back and said he tuned it (HP Tuners) and it did not fix the problem. He wanted to look at it and check some things. It has been almost two months. I call and he updates me weekly, but he has found nothing. The only code it shows is MAF, which he wants to try as well. I told him it's had three already. He has additionally been through the wiring and found nothing. I am waiting on a call back from him this week to see if he has made any progress or has any news. I fear for the worst. I really need some advice. The only thing I bought for the car and put on it are two aftermarket air filters (Spectre) that are like the K&N. I also changed the oil with the recommended synthetic Mobil 1. Can someone give me some advice other than that I'm stupid for buying the car and spending all this money on repairs? I have had some advice, so tell me if any of it is logical... 1. Fuel filter, 2. Air filters (something about the oil can mess up the MAF), 3. MAF, 4. Have torque management disabled, 5. A possible crack in the radiator support, 6. A crack or hole in fuel pump or water pump. Can someone who has some experience let me know where I should go from here. I don't want to spend a lot more money on this thing, but I love it when it runs right. It's fun. I want it fixed. Not to mention, no one is going to buy it with the problems it's having. Additionally, could the original tuner have messed something up within the car during the first tune? Does that happen? If so, what could be the issue(s)?
The bad thing is I don't know anything else about the car and what it has and doesn't have. 44k miles. Who knows how long it sat while wrecked.
I would appreciate any and all advice on the matter. Be honest with me. I want this fixed! I will also take recommendations for people who work on these things (East Tennessee area).

westc

Update: Heard back from the tuner/garage today. After going over wiring and everything else, he seems to think it is a possibility that the ECM is bad or there is a problem with that. Any thoughts/ideas? He said he knows a tech who is going to come check it out this weekend and give some advice. Any other responses are appreciated...

Russ K

The car may have been tuned in speed density mode previously. That would cause a P0103 Maf code, and will disable the misfire detection. Can you post the tune, and I'll look it over. With no cats, the exhaust will stink badly. Are the front O2's still in place? Maybe the cam is not stock.

Russ Kemp

westc

The only info I have is some info from the original tune. The car has been re-tuned by the guy who has the car now. I don't know that I actually have a copy of the actual tune information. All I have from the original tune is the dyno results; nothing else. I have posted all I have. They did not give me anything else. As far as info on the current tune, I don't have anything from him considering he still has the car and is still working on it. I haven't seen the car in months now. As far as the front o2s, I do not know the answer to that. I apologize for my not knowing. I am (almost) clueless when it comes to cars.

majorpayne317641

If the tune is absolutely correct then wiring, ecm, or , mechanical. I would swap the ecm and check, the maf error code just sounds like an SD tune. If that doesnt work than pull the timing chain cover and examine any slack in the chain etc, check the a/f ratio at those rpms when it does studder. I had a car with a big cam do this cause it would run way lean in one spot. Where are you located in Tampa? There are a lot of corvette specialty shops that can go over all aspects of what might be the problem.

westc

Actually, I am not in Tampa. The car was bought in Tampa; I am located in Tennessee, near Knoxville.

Thanks for the advice. I am supposed to hear the results of the ECM sometime this week.

westc

Update: the tuner/mechanic contacted me yesterday and said he "thinks" he may have found the problem. He said they did a check on the ECM and it is functioning properly. However, he believes there is a short in the wiring running to the MAF. The issue is that he thinks the short is actually inside the wiring harness. He was trying to decide whether to find issue and re-wire, or just replace the whole harness. He is not 100% positive this is the problem, but he has a pretty good idea. I'll keep you updated. He said if everything goes right and that is the problem, it may be corrected by this weekend or early next week. Fingers are crossed!

westc

Update: problem is completely fixed! I'm so relieved. Wanted to update the post in case anyone else has the same problem. Although the symptoms my car had can be a number of different problems (as I was told), at least this can maybe help someone or give them another idea to look at.
The problem did end up being a short in the wiring to my MAF. The short was down in the wiring harness. From what I understand, one of the prongs where it plugged in had broken and caused the short. He fixed the wiring and now everything runs great. The car is doing great. I picked it up Friday and have been enjoying it over the weekend! Additionally, he re-tuned and got some extra HP as well. So, overall, really happy.
Although it was a long process to figure it out (about 2 1/2 months at this place (and about 4 months total), I am happy with the outcome because it wasn't too expensive to fix, and the car is running great.
Maybe my experience can help someone else before they have to spend money they don't have to.
Thanks for everyone's help and suggestions.

tennblkc6

wow..glad to hear its all sorted! and thanks for updating the thread.