Audi 90Q ABY S2 conversion - engine running issues

[simyboye]

Just finishing off my 90Q ABY conversion. Starts etc but under load it misses and runs on only 4 cylinders.
Had a mechanic friend look at it. Replaced plugs and dubious coilpack and still misses when reving/ under load.

Removed injector plugs etc and get the real lumpy crappy tickover but the front cylinder nearest the front of the car makes little difference once injector plug removed? Injector is working... I'm pulling me hair out!

Anyone any ideas or anyone near me in Bracknell Berkshire help me out by looking at it?

Thanks

[audinut]

Just finishing off my 90Q ABY conversion. Starts etc but under load it misses and runs on only 4 cylinders.
Had a mechanic friend look at it. Replaced plugs and dubious coilpack and still misses when reving/ under load.

Removed injector plugs etc and get the real lumpy crappy tickover but the front cylinder nearest the front of the car makes little difference once injector plug removed? Injector is working... I'm pulling me hair out!

Anyone any ideas or anyone near me in Bracknell Berkshire help me out by looking at it?

Thanks

Im happy to try and help ,but have limited time so im not sure how quick id be . Im in ascot

[sam80quattro]

might sound daft but are the fuel pipes on the right way around?

[simyboye]

I will go check. Pretty certain pipes are correct.
Did notice after a while one pipe became loose. Could it be air in the fuel maybe that would cause a problem?

[Acidburn]

first thing, have you checked the codes?

if it runs fine till its under load then i'd check the wiring/coil pack if its missing but generally in my experience this clears up when its not under load.

if pulling the plug off the injector makes no difference then thats either an injector issue or the wiring to the injector. check behind the boot on the plug and if you use the search function i'm sure there is mention of a certain amount of current that should be present at the plug if you check with a multi meter.

Have you done anything with the car since when I saw it last and drove it? is the exhaust sorted now and the battery fully charged as if its low that will be causing issues.

If you can get the codes then post them up you will get some good replys from people like prj and urs4boy so if they reply its worth listening to all they have to say.

pm me your number and i'll see if i'm passing anytime soon and can have a look with you. I can bring some spares up with me like coilpacks, pos's, maf, wgfv etc.

do you have a boost gauge plumbed in yet?

[simyboye]

Contact number

Exhaust done, boost gauge done and battery fully charged.

Cant get codes up as not sure which plugs I'm looking for. Got vcds lite, will try again.

Be good if you could come have a look sometime.
Thanks pete

[UrS4boy]

Just finishing off my 90Q ABY conversion. Starts etc but under load it misses and runs on only 4 cylinders. Had a mechanic friend look at it. Replaced plugs and dubious coilpack and still misses when reving/ under load.
Removed injector plugs etc and get the real lumpy crappy tickover but the front cylinder nearest the front of the car makes little difference once injector plug removed? Injector is working... I'm pulling me hair out! Thanks

Sounds like a possible failure of the No.1 cylinder's power output stage (POS) channel.

Try this diagnostic procedure to confirm POS channel or coil/plug:

http://forums.quattroworld.com/s4s6/msgs/153152.phtml

If it is the No. 1's POS channel, swapping the pairs of POS connectors will move the miss to cylinder 4. Then you leave the swapped pairs in place and swap pins to move No. 4 to the spare "No.6" channel. Bob's yer uncle.

Pin-swapping hints: http://forums.quattroworld.com/s4s6/msgs/52184.phtml

In lieu of pin-swapping you can just buy a new 351A POS (POS info here: http://forums.quattroworld.com/s4s6/msgs/15284.phtml)

If you wanted to try to pull codes, the connectors are found here:

http://forums.quattroworld.com/s4s6/msgs/90409.phtml

Doesn't really matter though. Ignitions system failures (POSs, Coils, Coil to plug boots, plugs) do not through malfunction codes. That would be *too* easy.

[simyboye]

URs4boy. I'm on to that!
Front cylinder nearest head lights is number 1?
That makes little difference once injection plug removed. I'll check out the POS.
Thanks guys.
Will report back.

[AndyP]

Try checking the injector plug, I had a similar issue with a mis-fire and it turned out to be the plug. When you unplug it you will see that there is a pink plastic insert in the plug, this had become brittle and cracked on mine preventing the pins conecting correctly.

[bazburn]

Good to see you still at it... I guess the little one's starting to sleep a bit...

[UrS4boy]

Try checking the injector plug, I had a similar issue with a mis-fire and it turned out to be the plug. When you unplug it you will see that there is a pink plastic insert in the plug, this had become brittle and cracked on mine preventing the pins conecting correctly.

Another possibility. I did a post on that with your photos Andy (thank you, sir):

http://forums.quattroworld.com/s4s6/msgs/239238.phtml

[Fat Audi 80]

Coilpack boots (spark plug boots) these are known to cause issues at higher revs if they are old...

[UrS4boy]

Coilpack boots (spark plug boots) these are known to cause issues at higher revs if they are old...

True but his idle is lumpy already.