HELP - Cutting out on wot

[downhillfast]

My 94 S2 avant has developed a cutting out problem, it can occur at allmost any rpm and not allways on full boost, but it seems to only be on wot or very large throttle openings. It can run fine, then start doing it - I cant make it happen, and sods law, it wont do it in the presence of an expert! It cuts dead instantly, recovers immediately the throttle is eased but if the throttle held open it cuts in and out in the most violent way!
I have fitted a new throttle pot and air mass meter (amm was had it anyway) but I am getting peed off with it now. Any ideas?

BTW Great forum with some incredible cars. I can feel my enthusiasm returning.

[nesshead6]

I have the same problem, I replaced WGFV but didn't cure it. I know how frustrating this is, mine stopped doing it for months then did it twice at the weekend there. The fault code I get when plugged in is that maximum boost pressure was exceeded. Many people have suggested to me that it is down to a boost leak, but I don't think so as the problem is too intermittent. A leak can't go away for months then return... I think it may be the MAP sensor inside the ECU which is faulty.

[Hainch]

It sounds like a bad coil. Borrow all 5 from a friend that is known to work. easy 5min job.
do this before buying unessesary parts.

[mcandmar]

If its a sudden cut, as in feels violent enough to scare the crap out of you its overboost protection. In my case i also got a "maximum boost pressure exceeded" error logged.

It was caused by a tiny leak on the maf to turbo hose where it joins onto the turbo. I only found it doing a pressure test as the leak was before the turbo and not subject to positive pressure. All i had to do to fix it was give the hose clamp on the turbo a 1/4 turn, amazing how such a tiny leak can cause the ECU chuck its toys out of the pram. Without a pressure test kit i would have NEVER found it.

In my experience dodgy coil packs start to miss fire under high load or high boost pressures. When they do miss the engine just feels fluffy and holds back.

[nesshead6]

I need to get me one of these pressure test kits.....