a2oc

Hi all, I've got a B9 2.0T CYMC, 51k at the moment, sometimes I do hear and feel some roughness during idle. Which line is the one to check for timing chain stretch with VCDS?

Picture was taking when it's idling at 800rpm, at operating temperature.

SMac770

The adaptation values are the relevant ones. The adjustment ones are the real time operational values, specified and actual should track together. That curious that it's only +5° intake on a Gen3 evo. Idle value was +28° intake on a Gen2. Shows the standardized values will need to be reconfirmed for the B9 engines vs the B8 engines.

The normal adaptation value threshold was +-5°. You're not close to that. But again, the B9 community is probably going to have to re-work out what is normal and what is borderline based on values recorded at certain states of tensioner extension.

But to your symptom statement for looking into this, I don't think chain wear is your problem.

a2oc

I'll probably check and record the adaptation regularly and see how long will it take to get to 5 degrees. I hope it will be a very long period of time.

SMac770

https://www.audiworld.com/forums/a4-...-idle-3048030/

The exhaust side certainly seems to run the more negative adaptation. But there's no understanding of what that means.

https://www.vwvortex.com/threads/gen...ilure.9045457/

Looks like Audi changed how the Gen3 handles the situation. If you get a MIL and check codes and have P0016 or P0017, you just do the visual inspect and respond as documented in my post in the first linked thread. Seems a bit regressive, but maybe the dual VVT config makes using the adaptation value unreliable as a chain age indicator.

SchwarzS6

The roughness at idle, particularly at first startup is normal for the 2.0T engines. VW/Audi uses an emissions system warmup method which causes a rough idle when cold but allows the catalytic converters to come up to temperature quicker. I have a technical paper on this somewhere on my computer. Note that if you have a failing engine mount (which Audi’s are known for) then the mount cannot switch to “soft” mode properly so idle roughness can start to feel worse. If your engine mounts are not leaking then don’t worry about occasional idle roughness.

A4Audi4Fun

FWIW - just checked camshaft values for my 2017 A4 2.0T with stock engine CYMC, 90C and idling - currently 51,443 km / 31,965 mi; in service date Feb, 2017. Engine feels fine to me.

• exhaust spec/actual - 4.5 / 4.5
• intake spec/actual - 5.0 / 5.0
• intake phase - -0.3
• exhaust phase - -3.0