misfire and stutering Help!!

[Stoffle32]

Hey all
So took my car in for a service today, just a annual one for oil change etc.
Got it back and the car is misfiring and stuttering under acceleration, idle is also a bit sporadic...
Anyone had this before and know what the solution is, there are no errors on the dash and left my laptop at work so cant scan until tomorrow.

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If idle is off then likely to be an air leak somewhere.
Silly, but worth making sure the oil dip stick is in properly and the oil filler cap done up full.

Did they change the plugs?
TBH, there's not much else a normal service can do!

[coffey555]

If they changed the plugs one of the connections to the coil-packs might not be fully tight resulting in a weak spark.

Sounds like it could be running on 7 cylinders. If they have not changed the plugs it could be that one of the plugs is fouled. My car was really bad for doing that if the car was only moved a short distance in quick succession ie moved from customer parking to service bay, service bay to unused space, unused space to wash bay etc.

When it happened I had exactly the same symptoms as you only the check engine light would start flashing after a short time.

Much better now that it is running the 090 software now though.

[Stoffle32]

they didnt change the plugs and have checked the oil cap and dip stick they seem to be secure..

I also think it might be a vacuum leak just very strange that its happened after a basic service, unless the oil filter was not screwed on correctly but dont think you can get that wrong..
I have new plugs at home and all the tools to change them, might give that a try If audi cant sort the problem out when I go past again tomorrow to see what they say...

Oh another thing is its not all the time with idle and sometimes if I take my foot off the gas where it seems to be stuttering then back on the power comes on again...
wont rev past 7000rpm either at the moment, oil is 90 degrees +

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Quick n dirty test. run the car on idle for a few minutes. Shut off engine and then pull up the front carbon engine trim. Look for a nest of small black hoses (the vacuum lines) and follow the one heading to the airbox. There should be a join on this one which you can disconnect.
If you hear a "psssst" then it's holding vacuum pretty well otherwise... well... it's not.

Test for spark plugs - idle engine and let it settle. then pull the coils out one at a time and see if it is worse. If it is then the spark was fine.

The misfire detection will only really happen when it's warm and then try to hold a constant 30-40 mph for a while. This should be right in the happy zone for detecting misfire.
You may also get VCDS logs indicating a misfire but not enough misfire events to trip the MIL.

[coffey555]

Getting access to all the spark plugs is a right pita though, hook it up to a laptop or get Audi to have a look at it first before taking the engine bay apart.

Interesting that it is not reving past 7000rpm so it must be throwing error codes somewhere.

Hopefully running a scan will pinpoint the problem quickly.

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Depends on the reason - if it's being limited by the ecu or the mixture is off

[Stoffle32]

okay so got a chance to do a scan on the car
on Engine 1 its has open circuit/malfunction on lambda(oxygen) sensor
On engine 2 its has every cylinder that has misfired on that bank

am taking it back tomorrow im sure i could fix it but it seems they broke it so yeah..

[Stoffle32]

okay new update...
It seems that when filling the water coolant bottle for the engine the split water/coolant all over the left bank and it went into the coils...
They have replaced the coils free of charge and everything seems normal now.

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Ah yes - That'd do it nicely
Arthur commented ages ago that the Audi approach to waterproofing is a bit hit n miss.