s4 misfire help?

**tdigolf** · 01-01-2011,04:33 PM

hi there i dont normaly post in this section as i have a golf but my dad has a 2004 audi s4 cab with 40k on her, and recantly when starting it from cold it has developed a misfire and the engine management light comes on, if you drive a few miles then stop at lights turn it off and restart it then its fine, i have pluged in my vag com and it says "16684 random multiple cylinder missfire detected" if i erase the codes then the light stays off and is fine. untill its been stood a day or so then start it again.. anyone got any ideas?

regards tom

**Crasher** · 01-01-2011,04:43 PM

More than likely it is a coil pack, eventually it should identify the cylinder at fault but it could be a deeper problem such as a variable timing chain issue. What is the cars engine type code?

**a8 tech** · 01-01-2011,05:28 PM

as above iut if the misfire jumps from cylinder to cylinder without pattern and misfire totaliser is all over the place in mvbs then look at the cats for collapsing and blocking off the exhaust escaping gases.

**tdigolf** · 01-01-2011,08:12 PM

is there no way of findin g out which coil pack it could be before it says on the computer? the engine code is "BBK" and the gearbox "HHU" i think?

**Crasher** · 01-01-2011,09:42 PM

Yes, buy a new CP and fit it to each cylinder one at a time when it is misfiring, very tedious and likely to make another CP or 7 fail…

**tdigolf** · 01-01-2011,10:48 PM

owwf sounds cheap... cant i unplug one at a time and see which one doesnt make any difference?

**Crasher** · 02-01-2011,02:11 PM

Sorry but please don’t take this the wrong way but a 2004 S4 cabrio is worth around £11K and a genuine coil pack costs around £35. Please don’t tell me that when running a 344PS V8 155mph performance car that spending £280 on maintenance is problem!

Yes, you can unplug them one at a time and try and deuce the cylinder drop but the layout of the harness makes this quite difficult to do and moving the coil packs around a lot can upset them.

**a8 tech** · 02-01-2011,02:16 PM

lol, agree

**tdigolf** · 02-01-2011,03:18 PM

haha dont like wasting money though if it only needs one.. was fine today no light came on or misfire, might have a bit of damp with the weather? See how it goes not the end of the world if it does need a them though!!

**tdigolf** · 03-01-2011,07:51 PM

been fine past few days then on way home on 40mile trip today light just came on and started misfiring then soon as got home the light was flashing, plugged the computer back in but again didnt pin point a cylinder just said multiple/cylinder misfire, i erased the fault then it was fine again and the light stayed out..