aaaargh now wot

[bazer]

help guys. when my s4 starts to build up revs it cuts out for a second. im preety sure its electrics. it only does it as im piling the power on.just had its c service amongst many other things. when its idling or im taking me granny for a spin its fine. anyone any ideas about known faults of this nature.

[feffman]

Bazer:

Try new spark plugs and new plug wires. My previous S4 did the same thing until replacing plugs and wires.

Mark

[bazer]

hi mark.
just had new plugs when c service was done.think im gonna have to take it back to stratton motors who done the service.its been doing it since then and only covered 400 miles. just a pain getting back to them as its 200 mile round trip.

cheers mate. Barry

[jk1]

Hey Barry,

Did they install new wires along with the new plugs?

Cheers,
Jim

[petros]

My V8 MGB had the same problem, turned out to be a slight crack in the dissie Cap. peter

[scoule]

Dizzy cap is one thing it can't be, there isn't one!

What is your boost gauge doing at the time? There's a chance it could be an overboost cutout if the wastegate is stuck ...

[bazer]

just got off the phone to stratton motors they seem to suspect the waste gate also.i had a new turbo and gate fitted 3k ago and i noticed they had wired open the waste gate----is this common practice as they assure me it is.if i didnt love driving this thing so much it would be history at this time.i asked them if it could be the leads breaking down and they said doubtful.so it looks like the long trek back over to them next wk.
Barry

[Paula&Marcus]

bazer said:

just got off the phone to stratton motors they seem to suspect the waste gate also.i had a new turbo and gate fitted 3k ago and i noticed they had wired open the waste gate----is this common practice as they assure me it is.if i didnt love driving this thing so much it would be history at this time.i asked them if it could be the leads breaking down and they said doubtful.so it looks like the long trek back over to them next wk. Barry

Barry,
If you would wire open the wastegate you won´t see any boost at all !!!

Maybe you are talking about the EBPV-valve (=butterfly valve between the cat-pipe and the exhaust-muffler ??? Yes, indeed its common practise to wire this EBPV-thing open.

Marcus (confused

[cnh1990]

Is the acutator hose connected to the capsule?
Sometimes they fall off especially when someone is doing engine work.

We are talking about the turbo wastegate capsule and not the EBPV that is sometimes wired open.

[bazer]

sorry marcus yeah i meant the thingy.if the acuater hose was off would this give me this problem.bin out today in it and it is when you hit 3800 revs it does it just for a split second.i assume this is when the turbo boost kicks in.

[benfell100]

could this be the common rpm splutter encountered by every car at early boost stage due to underdeveloped ecm code? Your car has just been serviced which means the battery was probably disconnected, the ecm then has to relearn the fuel stuff for 50 miles or so and the '3K stumble' as its known, may be more obvious in this time. May be an idea to get the newer S4s code from Markus, this helps reduce/eliminate the stumble.
Dom

[Paula&Marcus]

bazer said:

sorry marcus yeah i meant the thingy.if the acuater hose was off would this give me this problem.bin out today in it and it is when you hit 3800 revs it does it just for a split second.i assume this is when the turbo boost kicks in.

Barry,
how much boost does the gauge show when it happens ?

Marcus

[oharedm]

I am sure Marcus will agree, we should be also to get to the bottom of this one with a Freescan log file.

I bet a plot of the TPS vs. Wastegate Duty Cycle will how up if the ECU can't control the boost and it is overboosting.

Dermot

[bazer]

hi guys im back. had a problem with pc. anyhoo you guys were spot on. i checked all the hoses and the hose to the acuater had a split in it. i would never had found it without you guys as it was on the underside out of view. i am forever in your debt guys. changed it today and back to seeing of bmws big style.once again many thanks
Barry

[benfell100]

Sorted. Always a nice feeling when listers have helped diagnose a glitch.