Recurring mis-fire issues

This is really a bit of an on-going saga.............basically I have had mis-fire issues with the 8 for the last 3 months, with the car going back and forth from the garage 4 times now.

The symtoms are the engine management light comes on, flashing at first and then after about 20mins of driving stays lit. The engine runs very lumpy, particularly at idle and fuel consumption drops to single digits. Each time I have had the problem its gone into the garage a been diagnosed as a failed coil. The sorry sequence of events over the last 12 weeks is as follows;

1st trip to garage - cyclinders 2 & 4 coil replaced. This fixed the problem for 2 weeks then the misfire came back; 2nd trip to garage - cyclinder 1 coil replaced. Again problem solved, this time for 4 weeks then same thing again with 3rd trip cyclinders 3 & 5 going. Again 2 weeks later and it had to go back again. This time, it was cyclinder 7 causing the problem, but asked them to replace 6 & 8 and do all the plugs as well (as I was told once one coil goes the other tend to follow, and thought it couldn't hurt to change the plugs as I don't know when they were last done).

..............so another 4 weeks later and the problem is back again.

I have searched this forum for related threads as well as trawlled the internet to see if there are any other causes, I read something about incorrectly fitted timing belts sometimes causing misfires but this could be a red herring as it didn't mention anything about it knocking out the coils. The first job I had done was the timing belt replaced when I bought it 6 months back, the garage I used were basically idiots so wonder if it could be related.

I would be grateful if anyone can shed any light on whats possibly going on, or even had a similar problem themselves?

Thanks in advance for any help!

[Conan_the_Librarian]

Have a read through this thread as I am having a similar problem. Its not coils as I swap them over and the fault stays with cylinder 6. It's not plugs for the same reason.

I get a scan readout saying number 6 injector is have intermittent electrical problems. Next diagnostic is the swap injectors around and see if the fault moves.

Do you have VCDS? I am surprised by the number of failed CPs you have had.

thanks for getting back so quick.............no I don't have VCDS, I can't recall the fault code that comes up when its plugged into the garages diagnostics, but I'll call them and ask (pretty sure they will remember as its been back and forth so often with same problem!!!!).

yeah, its really strange, I can just about accept 6 CP's failing within the same 3 month period if its a life span thing, but to replace them all, and plugs, and still have the problem come back is really frustrating. Also, the fact that once a coil is replaced seems to solve it for a short period keeps making me think 'something' else is the root cause and causing damage to the coils.

Can you re-send the link to your thread, or just give me the title so I can search it, as the link isn't working.

[Conan_the_Librarian]

Try this,

http://www.tyresmoke.net/forum/audi-...t-not-lpg.html

[ainarssems]

You should get diagnostics cable, Chinese cables are very cheap on e-bay and they will do all the basic stuff You need with the shareware of Vag-com, VCDS-lite or VWTool then you can check fault codes yourself. Without fault codes it is really hard to say anything as it can be a lot of things.

[The_Laird]

If you decide to sell the Avus 18" wheels, please give me a shout

[PsYcHe]

Silly Q.. But is there maybe an ECU re-flash available? My D3 had a similar issue when I got it and they flashed new code on the ECU.

thanks PsYcHe.........guess it could be ECU, I read on another forum about this causing problems with missfires, but that was another D3 as well.......not sure if same issues occurred with D2's. In any event it doesn't seem a very common problem (other than obvious causes) as I can't find many threads etc anywhere on a similar fault.

I'm really stumped and think I have no other options than to bite the bullet and take it to the local audi dealers (£140 per hour), I can't afford to be doing £150 every month but going no-where - I guess at least they may be able to get to the bottom of it......how much it will cost however is another story...eeeek.

I'm away on holiday from Sunday and then straight off to Asia on business for 2 weeks so it will have to wait until February now before I can take it in (not a bad thing as my bank balance may recover enough to afford it after the usual xmas pummelling).

For comedy value, as if this wasn't a big enough headache, I reversed the 8 into my brother in laws BMW yesterday. I managed to get away with just some minor scuffing to the bumper (easily sorted) and cracking the tail light. However, I caught the BIL's car right in the centre of the drivers door and really mashed it. I wont go into the full details but it was in our driveway (we live next door to each other) so no insurance cover and he had parked up behind me rather than in his space..........the tough S**T pal position won't really cut it as I can't manage the fall out, but suffice to say I made it clear if it ever happens again all bets are off. And yes the parking sensors did work but it was dark, he has a black beemer, no-one ever parks behind me and it was only 4 feet away........beep, beep, beeeeeeeeeeeeeeeeeeeeeep crunch........FFS.

[Conan_the_Librarian]

Death to all Beamers!

[Straycat]

Hi guys, just reading this and looking for help myself, just got my first S8 it's a 1998 car and in really good condition, have a few little niggle electrical issues with it but last weekend it started to miss, put my laptop on and it's telling me the fault is with number 6, if I turn off the engine and start up again it is ok for a short while? To start with I thought it was water getting over the coil packs as it started when driving in rain for the first time but now it is there all the time and seems to happen after hard exceleration, am going to swap coil pack with one of the other cylinders and give it a new set of plugs tomorrow to see if that helps but having read this I don't hold out any hope, did you get yours sorted and if you did what was it?