Engine Misfire on Cylinder 5

[1781cc]

OK, bit of a strange one this...

My car has one of the most random misfires, so much so that it is near impossible to pinpoint or describe. A while back a friend put the car on the ODBII memoscan and it flashed up an error code as a misfire on Cylinder 5 (I dont know the exact code - sorry), so took it back to the LPG garage and they cleared the error when they replaced the LPG injector for that cylinder.

Two weeks of driving and the car was fine, felt strong, no problems. Anyway, I was away on a job and wasn't running on LPG, just standard 97Ron and it started doing it again, feeling sluggish and jerky under load...

It has been suggested that it might be a coil pack (I dont know if thats likely as I dont know what they do?) - so I thought I would ask here in case anyone else has any ideas... It is booked in for a service on the 5th, and I am away till then, so any suggestions welcome.

It usually happens when the car is up to temperature, not necesarily when I am driving hard, it feels kind lumpy and jerky; short changing and less load seems to let it pass and then sometimes it clears. if I am in 6th doing about 50mph and put my foot down it can sometimes do it.

Ideas? should I panic about a big bill? LOL

[chunky79]

Does sound like a the fault i had the other week. You are advised to change all coil packs together and also the spark plug on which ever faulty cylinder. Coil packs are £30ish from the dealer.
If you could get someone with vagcom to check the car over and then change the packs yourself it will save you around £100!
I don't know whether the lpg combust's easier and thats why the fault is more obvious when switching to petrol?
Dunc

[1781cc]

I have been thinking about getting myself a VAG-COM setup for a while, but not sure what I need.

LPG is generally less combustible, but what your describing sounds similar to what I was thinking, Coil packs were on my list of possible problems. I am so-so mechanically minded, is the job easy to do?

Thanks for the response mate

[BlingBling]

You can get the basic VAG-COM set up for about £20 max, the cost of a fleabay cable. The basic software is a freebie from Ross-Tech. You will be able to view and clear errors´. The Ross-Tech wiki page will help interpret to translate the causes of each error code.

[chunky79]

Changing the coil packs is pretty easy. The nearside bank is alot easier than the offside. I think i had to move the header tank a bit on the nearside but then take quite a bit of the offside (covers, airfilter cover,maf and pipe). Just make sure the ign is off at all times.
Where is it you are based lee?

Dunc

[1781cc]

Hi Dunc,

I am in Milton Keynes mate, I have downloaded VAG-COM and am waiting for the cable to come through the post from fleabay, should be with me by the time I get back home on Friday. I used to do some work on my Supra and Type-R teg but nothing mental. I guess the thing being with this is that I have LPG injectors bolted into place on a rail above the inlet maniold so that will need to be undone and moved as well. Joy!

[1781cc]

Ok, car is running quite rough now, been away working but managed to get ahold of a vag-com install and cable, and I got the following:

Sunday, 04 October 2009, 14:54:40 VAG-COM Version: Release 409.1-US
Control Module Part Number: 8E0 910 560
Component and/or Version: 4.2L V8/5V      G   0030            
Software Coding: 0011711             
Work Shop Code: WSC 63351 

Chassis Type: 8E - Audi A4 B6
Scan: 01,02,03,08,09,15,16,17,26,36,37,45,46,55,56,63,76
-------------------------------------------------------------------------------
Address 01: Engine
   Controller: 8E0 910 560 
   Component: 4.2L V8/5V      G   0030
   Coding: 0011711
   Shop #: WSC 63351
1 Fault Found:
17983 - Right Engine Mount Solenoid Valve (N145): Short to Plus
            P1575 - 001 - Upper Limit Exceeded
Readiness: 0010 1101


I am really surprised about the cylinder 5 misfire not coming up again as an error, so I cleared the above code, fired her up, then off and rescan, same error... Didn't get much luck looking on google for it...

I think I will put the car in for it's service and get them to check coil packs and plugs, I hope it's that as it misses under load in gears at low revs.

Any one else had this problem?

[chunky79]

Post this up in the VAG-COM section lee and see how you get on there.
Doesn't sound like a coil pack.
Sounds like a problem the rs6's have but that cut's the turbo's out?

Dunc

[BlingBling]

The engine has two solenoid engine mounts. It appears that one of yours has gone. They are prone to leaking/failing. It is a fairly large job but there are DIY's ont he web covering this.

[1781cc]

OK, so £720 later and Inde-Tech couldn't find the problem with the misfire, said the car is working perfectly fine. what I did have done was a new Auxilliary rad, new rear pads + flexi hoses + fluid, wipers and full service...

I have been quoted £205 for the soleniod - does that sound reasonable?

Inde-Tech reconed the problem is associated to the LPG, but I gave the car to them running on Petrol. still, they said no error codes on the system, checked the coil packs and plugs for fouling, everything and no problems.

I think an independant LPG inspection is worthwile and I understand they can foul the cats if they are on their way out, but surely that would throw an error code if the sensors aren't working properly? or the cells are deteriorating.