Rough Rumbling Running

[AAH!]

Having returned a few days ago from a 2700 mile trip through france without a single problem (except for that bloody endless flashing exclaimation mark ! .... got to change the bomb), I've just come home from my first drive since to the Duxford Air Show. On my way up there, whilst driving through slow London streets at low revs and lows speed, my RS2 suddenly, with a very slight clonk, starting running rough as if it was firing on less the 5 cylinders. Idle was steady but power was down, pull off from a stand still it felt like the car was having to make an extra effort, a bit like being in the wrong gear when coming out of a corner. Got onto a faster road, acceleration was sluggish but the car did boost up to 1.8 bar, but still felt it was running on 4 cylinders. The sound, vibration and general rumble of the car throughout the range and in all gears reminded me of an old Daimler V8 250 I had.

As I pulled onto the motorway suddenly everything went back to normal.

45 minutes later after a good run and few moments after coming off the motorway at Duxford the problem came back and hasn't gone away.

I am thinking a coil pack may be the culprit (as they have done 129K miles) and I will have a snoop around in the morning and check the wiring to them, as well as checking the spark plugs (new 6 mths ago).

In the meantime does anyone have any ideas what else might cause this sort of problem?

thanks ... Angus

p.s. are ADU coils packs the same as ABY?

[newsh]

loose spark plug?

[robo]

ABY coils = ADU coils

[AAH!]

No luck in curing the problem as yet. Whilst tinkering today, I noticed a smell of petrol while the car is iddling.

I Have now done:

Output test as per SJM Autotechnic. All OK
Tested the MAF as per S2 Central. OK
Tightened spark plugs.
Blink Codes. None

I have done a basic inspection of the coil packs; the long rubber connectors are in very good shape still very flexable, some of the wiring is getting brittle and has 1 or 2 small cracks exposing the wire.

I will do a fuller inspection of the coilpack wiring tomorrow and try and get the sleeves off to inspect all the wiring.

From what I've read testing the coilpacks isn't the easiest of things without the proper tools.

Should I check for anything else before replacing the coilpacks?

Replacing them seems fairly straight forward, if not a bit expencive (although cheeper than it was), but my soldering skills are non exitant, so I may have to get some help with this.

Angus