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Nags
24-06-2010, 09:51 PM
Hi all,

I drive (http://www.vwaudiforum.co.uk/forum/#) a 2003 A4 1.8T 190 with has done 60k. Its had an ongoing problem with a misfire in cylinder #2.

It was first repaired in Aug 2009 and replaced the ignition coil #2, all spark plugs and a lambda sensor. When I got the car back it was running better but I could still tell it wasn't perfect - still a bit rough, lacking some power and response, and very heavy on fuel - averaging 15 mpg (http://www.vwaudiforum.co.uk/forum/#).

I clocked up only about 200 miles (over 10 months) then it started to misfire again on cylinder #2. Used a different garage this time; the mechanic replaced plugs again, tested coils, cleaned injectors, tested compression and fuel (http://www.vwaudiforum.co.uk/forum/#) pressure but still can't find the fault.

He suggested it may be an ECU fault which he isn't able to test for and would need to send it off. He's not certain this is the problem and I've already spent a small fortune.

Would appreciate any thoughts on a possible solution. Thanks.

towcestervag
24-06-2010, 09:57 PM
try the ignition amplifier mounted on the top of the air cleaner these cause a missfire on no2 cyl

Nags
24-06-2010, 10:03 PM
Is it also known as an ICM ignition control module? if so, I think it only applies to the earlier models - apparently my one has it built in to the individual coils.

towcestervag
25-06-2010, 07:05 AM
yes sorry youre right its built in
you say you have checked fuel pressures/compressions?
coil packs are poor!
did you fit genuine?
whats youre engine number so can check on elsa for wiring etc

Nags
25-06-2010, 11:08 AM
Yep compression, fuel pressure, injectors and sparks all ok. Not sure if genuine VAG coil, however it does work. Have swapped the coils around but the failure is still with cyl #2.

Spoke to an independant Audi specialist this morning, he said it sounds like all the usual suspects have been changed so he would start by stripping the engine down - 10 hours work for £1000 + parts!!!!

The last mechanic who worked on the car suggested an ECU fault - spoke to the ECU garage and will probably send it there to eliminate the ECU before any major engine work.

Thanks for your help.

Nags
01-07-2010, 07:03 PM
Hi all,

Here's an update; I got the car back today from the 3rd mechanic to attempt to fix the misfire - said it was the coil again! even though I'd swapped the coils around and the misfire remained in the same cylinder????

The 2nd mechanic had played around with the ECU which resulted in the remote key not working, so that had to be reprogrammed and I asked for an oil service, total cost £340. I'd already spent £500 with the 1st mechanic, the 2nd mechanic was a friend of a friend and said no charge for new plugs, diagnostic, cleaning injectors, fuel and compression test, but I gave him £20 for a drink. Total cost £860 for a coil and service!!!!!!!!

Drove out the garage and she drove like new, turbo kicked in and smile on my face. Five minutes later the revs dropped and slight misfire, kept driving, motorway blast and the dreaded misfire was back - no where near as bad as before but definately there!

3rd mechanic said bring it back - too right I will!

VAGMAN54
01-07-2010, 09:18 PM
you need to get the scope out and check power and grounds if the rest has been checked ,its always expensive to guess and stripping it down wont find anything unless you eliminate the rest first.a scope will pick your misfire up whatever range you drive at !! i just dont like this if all else fails lets blame the black box !! not aving a go just saying...

a8 tech
01-07-2010, 09:38 PM
8968

Ok the voltage feed and earth paths are shared accross all the coil packs so you just need to establish the activation signal from the engine ecu.
If you have access to a scope with dso then simply scope coil pack2.
If not then use a led test light and back pin 3 on the coil pack and run the engine.
The led should flash!!!!
If it does not flash check the coil pack pins
2+4 = earth
1= 12 volt
if these are ok disconnect the coil pack and the engine ecu
check the resistance from pin 3 to ecu pin 95 = less than 0.30 ohms
then check for mutual shorts and short to positive and earth.
make sure all the contacts are in order with a good wiggle on the pins to see if they are loose

If all ok but no switched live from the earlier led test then the ecu is defective.
Do not send to a ecu repair shop just buy a new or second hand ecu.
You can swap ecu and enable with vcds as its immo 3.
If all the electrics are ok carry out basic cylinder leakage test and also a compression test but from experience you have a defective output from the engine ecu.
Any fault code or misfire counter results?
If you are dealing with a workshop that uses terms like sound and common problem walk away as they are guessing and not carrying out basic checks.
This is how the parts bill racks up and then they point you to the dealer after they have lost the plot and finished fitting everything that's common, typical indi but this is a basic engine with a simple ignition system

Do not take offence but I would rather stick my dic k in a shredder than take any vag car to a indie who has no certified vag training history or reputation within the vag community

look here for a similar story (different engine but similar scenario)
http://www.vwaudiforum.co.uk/forum/showthread.php?t=100439

Nags
01-07-2010, 11:23 PM
Hi A8Tech and VAGMAN54,

Thanks for your input. After I posted my last comments, I took it out for another drive and suprisingly there was no misfire so I kept driving and still no misfire, had a good burn around some Essex A roads and all is well! Lots of power through the gears, smooth delivery and no misfire for the last 50 miles and fuel consumption is excellent. Fingers crossed it will stay like this. Feels so good to have her back - she was very close to being part-ex'd!

Thanks to everyone for their help.:beerchug:

VAGMAN54
02-07-2010, 08:45 PM
hope so ,for what you have spent on it so far 1 good mechanic rather than 3 poor ones may have found it ,anyway fingers crossed and happy motoring