Misfire and runnning really rough,engine management warning light flashing!

[jamin]

hello all you S3 nutters.

got some issues with my S3 at the moment.

intermitent misfire and engine management light flashing,runs really rough and huge loss of power.
initially only lasted for 1 minute then returned to normal.that was yesterday,today its worse and does it nearlly all the time.
really horrible to drive it like that,feels like it could stall at any time.

i took it to a freind who has diagnostics on his laptop.came up with misfire on 1and 4,he thinks its probably coil packs.
the coil packs were all replaced less than a year ago,they were recalled by audi so that was done free of charge.

i have read some of the posts on this subject but most of them say that the car runs fine,obviously mine does not.

just wondering if anyone has come across this before and know what the problem is?
i am very gratefull for all your help.

 

[firestorm]

If you know someone with another 1.8T engine car, see if they'll let you borrows their coilpacks so you can see if they're the culprit.
Otherwise wwap the coil pack around. 1>2 3>4, drive it and see if the misfire moves to the other cyl on vcds.

 

[jamin]

helllo,
yeh thats worth a go.think my mechanic friend owns a 1.8t a3 so should be able to swap them and see if its cured the problem.i would be a bit sorprised if it was coil packs as they were done less than a year ago.at least if that is the problem they should be covered under warranty.

 

[Alex C]

coil packs would usually be evident on 100% load in a higher gear i think. Is it running rough all the time or just when being pushed?

 

[Broken Byzan]

if they were anything except OEM a year is a good life for them.

The injectors rarely give problems and plugs tend only to be an issue on high boost rather than idle.

I've not seen or heard of valves leaking or causing misfires, so it comes back to the coils

 

[<tuffty/>]

When I coil pack goes it either goes and runs rough all the time or it will misfire under load and be fine when off the loud pedal... the CEL flashes on multiple missfires which it sounds like you are having..

This kind of missfire (especially as you have new packs) could be related to a vacuum leak or possibly wiring issues as the coil pack harnesses on S3's get damaged through heat...

If you have a leak then letting off the throttle a bit will let air escape but the ECU will be fuelling for what air it thought it has and will flood the engine causing the missfire... its unusual for more than one coil to 'go' at the same time...

I would be checking for air leaks first..

<tuffty/>

 

[jamin]

the coli packs are oem from audi.the old ones i had were in there for 2 years with no issues at all.

it runs rough all the time but it is intermittent.when it does start without the misfire i can drive it normally for about 10 mins before it starts to misfire.does not seem to be load related or temp related.

are the coil packs known to have intermitent faults because sometimes it seems fine but only for a short time before it starts to run rough.i would have thought that when the coil pack geos it would not come back! unless its perhaps a wiring fault.

 

[jamin]

hi tuffty,

thanks for your help,you are a legend.

i am thinking the same thing now,wiring fault or split hose.

somthig i did not mention before is that the fuel economy is about half what it should be when it misfires so its dumping a lot of fuel somewhere.and i did notice it was whistleing rather loadly before all these problems started.
dont know if that gives you any more clues as to what the problem may be.

 

[Broken Byzan]

something I did not mention before is that the fuel economy is about half what it should be when it misfires so its dumping a lot of fuel somewhere.and i did notice it was whistling rather loudly before all these problems started.
don't know if that gives you any more clues as to what the problem may be.

That makes a difference in diagnosis,Get yourself a smoke/pressure test done.