Intermittent misfire S3 no codes!!

[dhiren]

Hi all

My s3 misfires on start-up, (unsure if the cold weather has anything to do with it).
Seems to do it then clears up once warmed up, had it plugged in and data logged, doesn't show any codes or issues in the data.

Couple months ago I had cambelt done and a full service with BKR7EIX injectors, I'm just wondering can these injectors cause rough idle on cold start if not properly gapped etc?
I've changed out to genuine R8 coil packs since this started and it still does it.
Cars done 55K miles so not high miler, maybe there could be carbon deposits built up that would cause it?

Bit stuck, I had thought it could be injectors but that would throw a code right..?

Any help appreciated
Cheers

 

[Mike.M]

BKR7EIX are spark plugs not injectors.

I suspect you have carbon build up on the intake valves and possibly one or more lazy injectors. Noticeable on cold start up as that uses more fuel to warm up, but the fuel is not flowing enough to meet the expectations of the ECU.....causing a misfire.

Misfires do not show codes in my experience unless major ones, but can be seen in VCDS with the misfire count (resets after every engine off cycle.)

 

[xaudi]

Seems very common on cold start.

 

[Davill9]

S3 if mapped correctly or standard should not misfire.
VCDS
Engine
MVB 14-16

it has counter to see when and it shows you the cylinders to see if it’s multiple/random or if it is a specific cylinder misfire to look for.

there will only be a fault logged usually if if a coil goes down and you pretty much loose the cylinder completely. Single miss at a time won’t show even if you get a count of 50 say in 10 seconds over all cylinders