UrS6 AAN running problems

[wemyss]

Hi folks,

New on here, not sure why I have not come here before, been on other forum for several years.

Anyway. I have a 1996 UrS6 with 140k.

It started to run rough all of a sudden and was like it was missing or only running on 4. This did clear for about an hour of a two our trip home. However it is like this all the time now. It is running way too rich and obviously down on power. The running is much worse at lower revs and it seems to clear a bit above 2500. I have replaced the plugs and fuel filter (which were needing down in any case) and after that did not work, got into the modern age and got a cable and software.

The only code present is 00525 Oxygen Sensor (G39). I have tried bypassing the sensor and tried a replacement unit with no luck.

My gut feeling at the moment is a coil pack. Does my symptoms fit? I take it the ECU system can not indicate directly if it is a coil pack(s) failing??

Many thanks in advance for any help

Mark

[UrS4boy]

Missing and Hesitation Diagnostic Procedures

Likely a Power Output Stage (POS) or coil but it could just be a bad or loose plug or coil to plug "boot". You need to do some diagnostics. Read this (and note the part about pulling the injector connectors to determine which cylinder is missing) and report back:

http://forums.quattroworld.com/s4s6/msgs/22611.phtml

[wemyss]

Many many thanks, great info and I will get onto that as soon as I can. Thankfully I don't need to run the car at the moment so no major panic, yet

Cheers

[wemyss]

Ah I got a 2 minute look at the car today and after pulling the power from each injector in turn it is cylinder 4 that is giving the bother. I had a very quick look at where the POS's are by removing the panel and apart from the insulation to cylinder 3 wire gone in one part it all looks fine. I will swap over the connections tomorrow if I get a chance for each which if the SOP should shift the problem to cylinder 2, otherwise maybe coil pack 4 gone.

I am so glad I came on here as it feels now I am out of the dark and heading in the right direction! Soooo many thanks again!!

[UrS4boy]

Ah I got a 2 minute look at the car today and after pulling the power from each injector in turn it is cylinder 4 that is giving the bother. I had a very quick look at where the POS's are by removing the panel and apart from the insulation to cylinder 3 wire gone in one part it all looks fine. I will swap over the connections tomorrow if I get a chance for each which if the SOP should shift the problem to cylinder 2, otherwise maybe coil pack 4 gone.

Definitely swap the two sets of POS connectors, in pairs, to the other POS. I think, because of No.4's position on the POS, if it is a POS problem, the miss will move to No. 1, not No.2. (2 would be the equivalent of 5, 3 the equivalent of No.6. Oh wait, there is no No.6 ) If the miss does work, you can potentially use the spare channel (the No. "6") channel on the original 4-5 POS to give No. 4 some new life. Let us know what happens.

[wemyss]

You are right and my mistake, I mean't cylinder 1. I did this Today, switched them around and cylinder 4 ran fine and cylinder 1 was not. Problem solved it seems!!! The good news as well with them switched around only 1 failed, so channel 6 is good it seems as otherwise 3 would have gone out too. I have not had time to look at the connections yet to see how easy it is to switch 5 over to 6.

Many many thanks again, I would never have thought to look for this on my own!

[UrS4boy]

Power Output Stage (POS) pin swapping hints

You are right and my mistake, I mean't cylinder 1. I did this Today, switched them around and cylinder 4 ran fine and cylinder 1 was not. Problem solved it seems!!! The good news as well with them switched around only 1 failed, so channel 6 is good it seems as otherwise 3 would have gone out too. I have not had time to look at the connections yet to see how easy it is to switch 5 over to 6. Many many thanks again, I would never have thought to look for this on my own!

Good news. Here is a link to some hints as to how you are going to swap the pins in the 4 pin ECU to POS harness connector from position 4/4 to 1/4 and then move the cylinder 4 pin in the 3 pin POS to coil connector to the empty location:

http://forums.quattroworld.com/s4s6/msgs/52184.phtml

[wemyss]

RESULT. I now have my AAN running on all clyinders again just by switching over to the spare channel. I don't know if I have just got used to running my old 2 litre 5 pot 90 this last couple of weeks but the S6 seems to be pulling better too. Maybe the change of plugs and fuel filter has made this difference.

All good, huge thanks again!

[UrS4boy]

Great news. Your UrS6 will defiinitely be pulling better now that it is literally firing on all cylinders. Did you use my pin swapping hints or did you figure it out on your own? Either way, great news.

[wemyss]

Yep, was meaning think it is pulling better compared to before it started playing up. Used your tips indeed, perfect instructions which made for a very easy job! Your a hero!

[macspring]

Agreed,

He's pretty good, the links king, nice one Dave.

[UrS4boy]

He's pretty good, the links king, nice one Dave.

Thanks. I've just been around these C4 UrS cars long enough to have written something on almost every problem. Sometimes, even before there is a problem. Glad to help.