Anyone with code for AAN ecu s4/s6

[diesel des]

All the pipes seem air/gas tight. I think it may be a slight intermitent miss fire under load. I got the engine wet (Had bonnet off painting it and it rained) and the problem got worse. It them went completly of no 1 cylinder even at idle. I removed the coil pack cover and found lost of water round no 1. So i dried it off and its back on 5 again. I then put my other set of coil packs on and still i have this miss under load. Its not completly off a cylinder just seems weak. I installed new plugs too, no difference. Can the POS moduels casue a weak spark? I would of thought they would eather work or not? I have a few spare so i will swap them. At this rate of swapping i will have my URQ ABY under the bonnet of the s4 complete with gt30r............

[mojogoes]

I take it Des you've done a compression test.

[diesel des]

Yes compression seems fine. Ok, the problem gets worse the hotter the engine gets, eg after a real hard run over twisty roads? What does that point at? Will try the POS at the weekend.

[mcandmar]

I would bet on the POS units, my old mans S4 had that issue with a slight miss before 2000rpms and a rough idle. Of course he robbed them from my aby project

[diesel des]

It seems odd as it wont miss at light load etc, only at full load. If anything it seems worse now i have changed the plugs and coil packs. Wouldnt the POS miss all the time not just under load if it was faulty?

[mcandmar]

We found it was more heat related, if you ended up sitting still in traffic it started to run on 4 3/4 cyls and would miss when you tried to floor it, felt like the overboost protection kicking in. And always had a stutter just before 2000rpms, both problems went away when we changed the POS units.

Not sure about light load effecting them, we did however have a problem with the rubber connectors from the coilpack to spark plugs, after changing the plugs (trying to sort the above problem) it started missing erratically, we found two of the rubber connectors had cracked and was arcing to the cyl head. You may be unlucky to have both problems, i would swap out whatever you have on hand spare...

I took us a while as we started thinking coil packs which had no effect when we swapped them, then we changed plugs which made things worse until we changed the rubber connectors, and then the POS units which cured it. If we did the POS units first it would have saved a lot of time and hassle.

Mark.

[merlin's S4]

It seems odd as it wont miss at light load etc, only at full load. If anything it seems worse now i have changed the plugs and coil packs. Wouldnt the POS miss all the time not just under load if it was faulty?

No, the POS is as likely to cause intermittant missfires as a coilpack, especially under load. The problem is often worse when the vehicle's warmed up as very often the problem is due to deterioration from heat. You should always make sure you have a good heatsink compound where the POS is mounted. If you're sure it's not the coilpacks then it's very likely going to be a POS or possibly a break down in the wiring somewhere! There is a spare channel on one of the POS's so if you can work out which cylinder it is, you can re wire that cylinder to the spare channel. I also have a couple spare sets of POS's if you want to try them!

[diesel des]

Ok POS it is then. Hopefully my other ones are ok. The rubber boots look fine too. I picked the best 5 out of the 10 i have. I also covered the inside of the connectors at both ends with silicon grease to keep water/crap out and spark in.

This is one of the reasons i like diesels. Dam spark ignition is so sensitive.

[diesel des]

Thanks for the help/offer guys. I will try the spare pos i have and see what happens. Are these things deer new? I know if its the coil packs i would just swap to the newer 034 1.8T solution.

[diesel des]

ok another update. I swapped the other pos's i have in. NO difference. I swapped the coil packs again. No difference. Now i am not sure the spare pos and coils are good. But is seems odd they both would have the same fault. Maybe not. Both ways im pissed off.

The fault only really showes up when the car is real hot, eg 130deg c olil and 95 deg water temps. Eg open the bonnet up and red hot turbo. When i got it real hot it actually went off a cylinder at idle. But not long enough to find out which cylinder. I was pulling injectors off and it may of been cyl 3 or 5.

Could this be a bad injector? Im lost. HELP!

[diesel des]

Another update. I did 200+ miles in the car yesterday. Mostly motorway. Drives real well, with barely a detectable miss at all. Then i hit belfast traffic and the miss got bad again. Deff related to temp. I think i have 2 bad sets of coil packs. Is there anyway to measure anything with these electricly?