BRING IT

I took my car to the shop and it is running fine. They were just doing a few adjustments and I wanted them to make a few passes on the dyno. Well I get a call saying that the car is breaking up at 4,000 to 4,500 rpms.

They change the spark plugs and look at the wires to make sure they are not messed up. Run the car on the dyno and same thing.

Any ideas??

Mark2009

Yeah... if the shop has a dyno and can't figure out what's wrong, take it to another shop. Quickly.

Especially if it was running fine when you took it to them

ProEFI

I don't know how you can sleep while they can't figure out what's wrong man. take it out as soon as you can.

Mark2009

Well let me add this as more constructive:

If the car was running fine before they 'tuned' it, tell them to put the original tune back in it (whatever tune was in it when you took it to them).

If it runs fine after that, then drive away, very fast, and don't go back . . . hopefully they won't ask for any money from you.

c5racr1

If they changed the plugs, check to see if they put a lot of anti seize on the threads. I did that once and had the same issues you speak of. Changed the plugs and it was all better, after wiping as much anti seize off as I could

CB1953

What shop?

BRING IT

I'm not blaming the shop just trying to figure out what it might be so we can get this issue fixed. They were not tuning it just running it on the dyno to make sure everything was working like it should. I had a wire come loose on a BAP and was having them check to make sure its still coming on when its suppose to.

The funny thing is I drove to the track Friday night ran 6 times and drove back home. Then Saturday night went to a car meet and did a couple of pulls with no issues. I then drove it to the shop Wednesday and they were adjusting my purge solinoid and securing a couple of wires. Then it goes on the dyno and now its breaking up.

Mark2009

If a shop with a dyno can't solve the problem, you need a new shop -- it's that simple.

We can't look at the car, we can't data log it, we don't know codes it's throwing, we don't know what's been changed or modified. Too many unknowns.


.

TnRZ06

I would start with the area where they worked on the purge solinoid and wires they played with as nothing else seemed to be touched?

BRING IT

I drop the car off this morning so we will see if they come up with a fix. I did tell them the one of the spark plug wires was touching the back of the alternator but don't know if that would cause it to do that or not.

Its wierd because it drives completely fine below 4,000 rpms.You would never know something is wrong until you smash the gas and go above that rpm.

duhveed

Had the same problem. Changed the plugs and it was good to go

BRING IT

Car is still not fixed. They changed the plugs and also tried a brand new set of plug wires and its still the same. Next they are going to take off the valve covers and check for any broken springs. This is crazy!!

Michael_D

Could try to clean the MAF. The ECU with stock cal hands off fueling duty to MAF from VE at 4000 rpm.

CHIWS6

i had a similar problem, i changed plugs, wires, coils, and injectors. The car was still misfiring up top, i took the covers off and 1 of those valve springs was broken

BRING IT

What did that cost to fix? Did you just replace one or all of them?

CHIWS6

I purchase the springs in the winter when I swapped out the cam but when I took to get it tune I was having that problem. The springs had roughly 300 miles, I called TSP and they only sent me to replace the spring that was damaged. I just had to pay for shipping which I should t have to but oh well, at that point I just want to get my car fixed

Dirty Howie

Ahhhhh, this brought back memories of when I used to tune my C5.

But I think this would make more sense if they had messed with the tune.

I think he either broke something on his last run the night before and didn't notice anything wrong driving home easy or the shop did something before the dyno run.


DH

jnv255

That's weird, TSP sent me the wrong thing once, after we figured out exactly what they sent and what they should've sent, they next day'd the part too me free of charge..
Damn to think about it, I forgot to send the other part back, it's in the box ready to go.... guess I'll do that Monday. It's only a few $$ part, but that's besides the point.

To the OP.. Man if your car was running right before they touched it and if the issue is from something they did (kinda sounds like it) I hope you're not paying for their screw up. Had a local shop not put in a new release bearing when I got my DYAD put in and it squealed from day one. Thought maybe it was a belt or something, told them to look at it, brought up the release bearing and they said they out one in. Took it to Chevrolet that have quite a few guys in service the drive Vettes and they said release bearing. Long story short, I got it out of the local shop that they didn't put a new one in "they looked at it and it looked good" and then said I only charged you half price to help you out, but then wanted to charge me (half price again so it would've came out to be full price) to go back and put a release bearing in... After they lied and knew damn well a new one should've been put in. I flipped the F out, made them redo it for free and I ended up watching the entire process...
My car only goes to Lamar Walden Automotive from now on and it's 2.5hrs away....
Hope you get it sorted out and you don't have too to threw the same crap I did

BRING IT

Yeah it was either Saturday night when I did a pull or it happen on the dyno. When I was driving it to the shop I probably didn't get on it hard enough to notice it if it was already messed up.

BRING IT

The guy I bought my car from took it to Lamar.