Rough running under 3k is it POS ???

[BrianSmith_S2]

Hi, having had car back and running great again i was upset to discover it running and sounding like a Impreza the other day on 4 cylinders on light throttle below 3,000 rpm.

Did a search and usual suspects were POS, plugs or coilpacks, but as it was at idle and lower revs/load it pointed to the POS. However, at first replaced the usual F5DPOR plugs with some old ones i had in my 20V coupe F6LTCR.

With the different plugs it ram smooth and i could actually accelerate although i was aware they were the wrong plug type so drove her gently to G&S to buy a set of 5 new F5DPOR.

With the new plugs fitted the rough running problem returned so i guess the lower resistence of the plugs had enabled the weak POS or Coil to operate.

So question is... where do i source one from? Internet searches have proved useless, theres not many decent car parts suppliers left out there Euro car parts showed up the Beru ZM 027 for the S2 thats used on the V6, but the hole spacing is 45mm compared to 55mm for the ZM 063 Beru list for the S2 and both listed at £102.

I guess im off to a VAG dealer tomorrow for a 4AO 905 351A

[UrS4boy]

Power Output Stage (POS) Info

If you track down the issue to No. 4 or 5 cylinder (e.g. by pulling the injector leads one by one at idle to see which cylinder does NOT make idle worse), it is possible to use the spare channel in that POS for the problem cylinder. This is explained here:

http://forums.quattroworld.com/s4s6/msgs/15284.phtml

Otherwise, you can use a good used brown Hitachi/Beru POS from an Audi V6 (mid-1990's) as a tide-me-over.

Good Luck.

[BrianSmith_S2]

If you track down the issue to No. 4 or 5 cylinder (e.g. by pulling the injector leads one by one at idle to see which cylinder does NOT make idle worse), it is possible to use the spare channel in that POS for the problem cylinder. This is explained here:

http://forums.quattroworld.com/s4s6/msgs/15284.phtml

Otherwise, you can use a good used brown Hitachi/Beru POS from an Audi V6 (mid-1990's) as a tide-me-over.

Good Luck.

Thanks for your reply... but with DJones help and use of his spare parts we discovered the POS units were fine. It was in fact the 4th cylinder spark plug boot that was split and the spark arcing across. With a replacement from Darren shes running fine now

[DJones]

No problem, good to hear all is well. Its often something simple...

[UrS4boy]

Missing and Hesitation Diagnostic Procedures

Thanks for your reply... but with DJones help and use of his spare parts we discovered the POS units were fine. It was in fact the 4th cylinder spark plug boot that was split and the spark arcing across. With a replacement from Darren shes running fine now

Always the first electrical thing to check: Plugs and boots.

Here is a Missing and Hestitation Diagnostic Procedures post for future reference:

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