hhughes1

Understand that if you mod your car and develop a problem like this where the root cause is not obvious, the dealership wants to blame the mods rather than investigate the way they would on a stock car. It is perfectly reasonable to them to blame the headers or tune rather than admit that this setup has worked fine for more than 2 years and is working fine on hundreds of other C63's as well. With that I have ordered a new ECU and once it is installed with stock files, they are willing to seriously troubleshoot. There is a real possibility that the ECU itself is causing the problem which I will know if the problem is solved by installing a new one. According to the head AMG tech (who has been very cool about the whole thing) he has seen two ECUs that started causing problems and would not allow stock files to be reloaded. Of course the warranty for the ECU was voided due to it being removed and tuned. I will update once we know more.

jvanbrecht

Just out of curiousity, what was the cost of the ecu?

BerBer63

they are 14-1500 plus 1 hour labor to load depending on dealership

4ramin

hey buddy, did it end up being the ECU?

_AMG_

Any updates?

hhughes1

The new ECU with stock tune files was just installed and the car continues to misfire after about 5 minutes of driving. The dealer is not willing to look any further into the issue unless I agree to pay time and material while they blindly replace every thing until it starts working again. They claim having headers on the car prevents the diagnostic equipment from working as it continues to point to the exhaust system as the root cause. They offered to replace all the spark plugs and switch coil packs from the left bank to the right for the value price of $700. I politely declined and drove the car home. The non tuned ECU does not like the headers AT ALL and I put the old ECU back in to drive it. The misfire is still there but mostly just at idle and during acceleration. At steady speed you don't know it's having any issues. I have the new ECU on it's way to Andy and once it is back the car is going to the shop where Keith has had all the experiments conducted on his motor. Jerry, the shop owner has been deep into the 156 and should be able to resolve the problem.

Big lesson here is that once you make any visible modifications, be prepared for the dealer to wash their hands of any problems that you may have with the motor and transmission. I knew that going in but I was surprised by their inability to diagnose issues in a modified environment. I am not going to pay MB rates for a blind man to find the problem.

_AMG_

I hope this issue gets resolved asap. I would check with an independent MB shop to see how much they quote for spark plug and coil pack replacement.
Please keep us posted.

Sincity

*BANGSHEAD* I wonder how having a more efficient exhaust is causing a misfire? I'm not a mechanic, but wouldn't that be on the intake/ignition side of the motor that is causing these issues or a sensor that may affect timing? You still have your O2 sensors, right?

hhughes1

I know the MHP headers have at least one bung for an O2 sensor and they also come with some extension harnesses to reach a little further than stock. For all I know one of these sensor wires may have gotten damaged. You can see both of them wire clipped to the flange holes. Bottom line is I will soon have an MHP tune on a fresh ecu and an MHP track specific tune on the original. Once the car is running again I will be a happy camper.

Dads C63

Howard,
We can do the plugs and coil packs if you want to. They are easy.
No matter the case Jerry will find the culprit.
He knows this motor backwards and forwards and has done the build many times. He's one of the few that knows what he's doing on these cars. If you need any work done I highly recommend him. I know we are in Florida but I know he's already had M156 motors shipped to him for rebuilds so he knows the game. He also knows the trannies and can help there as well.

He custom built the diff cooler for me and has done many of my modifications. For the nitrous build I would recommend Macedo Motorsports. Larry is great with after market stuff. He usually works on Vipers and exotics. Just a plug for my two very hard working mechanics if any of you need a good mechanic to do your stuff!!

hhughes1

Thanks Keith,

Eight new Denso iridiums are on my desk. Perhaps after cars n cafe we could go ahead and change plugs, switch sides on all the coil packs (I also have a tester) and clean the MAF sensors. We could put the car up on Jimmy's rack and visually inspect the o2 sensors as well.

mthis

Sry to hear. You issue with the dealer plain sucks!!!
Could you take the exhaust off and put the stock tune on and then go to another dealer?
That would be u best bet for u pocket.

propain

Carful the ethics police are going to hunt you down now...

Sadly im sure they share info and have added the information to his VIN already.

mthis

idk

Sincity

Howard,

I see both bungs on the MHP headers. It would be great if you can just swap parts with Keith and rule out each item one-by-one rather than play the experimental game with the dealer commiting you to buy each part.

hhughes1

Moral of the story: Never be "too busy" to take the time and check the obvious.......Guess which ones came from the problem bank

Very sad that the MB tech's were so focused on the modifications that they didn't bother to pop out a plug and take a look. Can you say computer dependant.

Car is GREAT now, likes the Denso plugs and the MHP tune.

Muskoka_AMG

****ing stealership...

Maverick1975

Thats quite an amzing story Hhughes, checking spark plugs seems like a simpole first step and yet the so-called experts completely missed it. I am gobsmacked at their incompetence. You are so right, if the computer doesnt diagnose it therefore cant be a problem, makes me wonder why these guys ever wear coveralls and rather than just a suit and tie with a pocket protector

GermanCars

How many miles on the original spark plugs? Did you measure the gap difference new/old? A slightly cooler heat range plug might be in order should you rack up much track time.

NORTH 44 C63

Hi hhughes1. Glad you got that sorted out.

Can you tell me exactly which Denso Iridium's you installed. Part #??

Thanks

hhughes1

http://sparkplugs.com/results_app.as...1&AAIA=1443250

Here they are $13.50 each. Every other site was charging $23-$25 per

hhughes1

These Denso's are supposed to be slightly cooler and they are pre-gapped at 0.43" They had 26,000 miles,many track days and plenty of race fuel used. The same bank had a cam position problem at an earlier time which may have hastened the electrode fouling on those specific plugs.

propain

Unreal.. Glad you got it sorted out! You should go back to the dealership and ask to speak with the shop foreman. Take those with you and show him.

NORTH 44 C63

Thanks. No issue running a cooler plug??

hhughes1

Big thanks to Keith (Dad's) for staying late tonight and lending a hand. Meeting you was worth every dollar I paid for the AMG