During start up- rough lide/misfire

[RS6NOR]

Drive the car until it is at normal temperature, take home and park up overnight. Next morning open bonnet remove no 3 coil and plug and look in cylinder for water ingress. This will be easier with an endoscope camera. If you see a small amount of water / coolant you have either a cracked head / block or head gasket failure which is small and seals with heat expansion. A friend recemtly came across this on an R8 that the local dealer couldn't diagnose.

Thanks for your input.

I checked for water leak after i had no success installing new coil and injector on cylinder 3. The workshop recorded the water level and set the coolant system under small amount of pressure over and left it over night. They used a tool designed for this. They did also take analysis of the water to see if they found traces of hydrocabon. This is done under the assumtion that if water leaks into the cylinder with no pressure present you will have a leak the oposit way when the engine is running. The test did not identify a reduced fluid level in the reservoir or traces in the water.

Can the teori about water leak still be valid after the results from the two tests above?

If yes, how is that possible?

[Shoppinit]

If it was me I would swap all the bank 1 injectors, coil packs and plugs with bank 2 to see if the problem moves.

Maybe you are putting too much faith in the ECU telling you the misfire is at cylinder 3.

Have you gone through the misfire logs with the Vagcom for each individual cylinder to see if there are any other cylinders misfiring occasionally?

[Shoppinit]

I wonder if a bad cam follower could cause this. Not lifting the intake valve enough so the mixture is bad in that cylinder. It would be worse after leaving the engine for a few hours when the oil drains out of it. Just a thought I just had.

If you do what I suggested in my previous post, then that might help to confirm or eliminate.

[grizz]

Have they done a compression test from cold ??

[Ryan_Pestell]

As Shop has said, mine constantly said missfire on cylinder 7, yet i moved that coilpack and problem remained on 7, changed all 4 coils on that bank and viola problem gone.

I wouldn't put faith in the ecu diagnosing the correct coil/inj after my experience

[RS6NOR]

Have they done a compression test from cold ??

Talked to the garage today and he could not remember. This is some time ago... Their normal procedure is to conduct the compression test with a warm engine so they where quite certant that this was done with mine as well.

I guess the next step will have to be to do a compression test when the engine has been standing over night?

I am located in Norway so i am fare away from your shop. If i was in UK i would knock on your door tomorrow
Is there anything spesial they should do compared to a regular test in addition to ensure that the engine is cold?

Your input is very much appricated.

[RS6NOR]

Have ordered a compression test Tuesday next week. Test will be conducted with cold engine, car will be stored in the Shop over night and not started before compression test. Ater what i understand there might be analomies when conducting the test on a cold engine , but i guess a leak to cooling circuts will stand out?

If the test conclude a leak i would have to take the high cost of changing cylinder head gasket. If the test do not indicate a leak i plan to change the coil bank.

Will post results from compression test when i have the results.

[RS6NOR]

I have posted results from compression test on the original post. I had to do that to attach the compression test print out.

[Shoppinit]

Good results.

[Ryan_Pestell]

so when you changing the coilpack on the bank?

[Shoppinit]

^^when he's exhausted every other possible cause, no matter how implausible.

[RS6NOR]

Quote from my update in the original post:

Delivered the car to the Shop yesterday and they put on ramp before wnding work yesterday. So this morning the car was cold and they condcuted a compression test before starting the engine. The compression test does not have clear indications of a leak. There are some variance from highest to lowest cylinder, but according to the Shop this would be looked at as inside spesifications. Please find the comptest attached.

When the test was condcuted they did some interesting observations:

1. When they removed the spark plug on cylinder 3 the sparkplug bottom had a lighter color than the other sparkplugs.

2. They also went in with a camera and the top of the cylinder had a lighter color. Cylinder 3 was moisture inside and the others was dry....

3. they cliamed the water level in the expansion reservoir was reduced from last time. Estimated a loss of 1 liter.

Based on this i guess i have reach point of no return.... i need to pull the engine and change head gaskets and potensially cylinder heads (checked with Germany and they where 1700 EUR/ea and i can probably add 30% to that for the price in Norway). Anyone out there with a better idea?

[imacool]

You mean 1700 EUR for a head gasket and 1700 EUR for a cylinder head plus labor cost on top of that? That's insane, especially the gasket price...
I would look for someone selling an RS6 engine only or for someone breaking an RS6 for parts.
Have you got a second car to use in the meantime?
Man, sorry to hear your problems.

[Shoppinit]

Aren't you blowing white smoke? Losing a litre without driving the car is a huge amount.

[Shoppinit]

Also, how can it be dripping inside the cylinder freely but coolant system pressure test shows normal?