Stuttering - ARGH please help

[Monkeyboy]

Hey Guys n Gals...

I have been having probs with my scoob...

Uk MY98
Normal mods - K&N filter, dump valve, HKS exhaust, SS Downpipe decatted.

Its been stuttering and coughing during aceleration... and cutting out, the dump valve has been going mad.. :( :(

This week i had the Lambda and MAF replaced as these are the usual culprits and all was good for a couple of days :) but now the stuttering is back.. :(

Anyone got any ideas???

Thanks

MB

[BIGMIKEYBOY]

What DV are you running mate?

My P1 used to idle badly and sometimes stall when i had the Blitz fitted..., removed that and replaced with HKS SSQV, and the problem disapeared!

Mikey

[gtmracing]

I too had these symptoms tonight on my travel home while using the motorways, it seemed to clear if i dropped it down a gear, accelerated hard then pooped it back up to top gear, then it would settle back into the stuttering mode after a while when i was wanting to overtake. I had a look under the bonnet to see if i could see if any pipes had come off (none found), but did notice that the DV hadn't shut properly (with the engine not running). Is it meant to be shut when the engine is off a partially opened? or do i need a new DV?

All help appreciated

[Monkeyboy]

Mikey - its a Bailey Atmospheric... not had any probs so far with it seems to be opening and shutting properly

The dump valve should be open when the engine if off... its the engine pressure that shuts it when the enigine is running.... Sounds like our syptoms are pretty much the same.

Thanks

MB

[Scott.T]

DV should be closed when the engine is off or idling. The valve should only open when there is positive pressure at the turbo side in relation to the engine side.

i.e you close the throttle when on boost, the engine side goes to vacum and the turbo side is still presurised by the turbo..hence PPSSSTTTTIIISSSHHHH. The excess pressure opens the valve.

You will not have positive pressure at idle, but a vacum on both sides (your boost gauge should shopw this.
When engine is off, both sides will see atmospheric pressure hence it will still be closed.

[gtmracing]

I got one of my techs to have a look at luchtime, it would appear that my DV is busted as the actual spring and valve isn't opening when you let off the gas, the piston still moves, but seems to have become separted from the spring and valve.

Gary

[Monkeyboy]

Ahhhh... ummm thanks Scott - maybe mine is bust too..???

[Dyney]

MB,
Have you checked for loose pipes? Check all the vacuum pipes are on.

[Monkeyboy]

Hey Matey

Yup been through all the pipes I can see and cleaned boost solenoid etc and still dong the same..:( :( :confused:

So.. I gave up trying and decided to give it to Mike :D :D :D

Hopefully he can work it out

MB

[Dyney]

I know, I was there while you were on the phone :)

Was also in the Scoob you followed Tuesday (if you were with Jen) ;)

[Monkeyboy]

Ahhh.. I thought I recognised the voice... ;)

Yup was in the car with the misses, No enjoying being ferried around at the mo.. miss my scoob too much :(

But, Im sure Mike will work his magic.

[gtmracing]

on my way to work this morning, i lost all pressure from the turbo, and all i could keep hearing was the pressure being vented to the atmosphere every time the turbo spooled. Once at work, up went the bonnet and i discovered that the IC was almost out of the top most hose, both the Jubby clips were very loose, so tightened everything back up and hey presto......DV is working again :woohoo:

Strange how the Jubby clips had slackened off so quickly:2ponder:

[Dyney]

Strange how the Jubby clips had slackened off so quickly:2ponder:

Slackened since when :rolleyes:

[gtmracing]

Slackened since when :rolleyes:

Ok. what i should have said was 'how strange that they had undone themselves to the point that you could actually spin them around the hose as if they hadn't been tightened up when they were put on'.

But last time i checked everything was tight, i forget how long ago that was:2ponder:

[Monkeyboy]

Car all fixed now!!! :)

Mike Rivett and Dyney working their magic... A nice shiney new MAF and all is well.. Thanks for your help guys..

MB

[Dyney]

Just glad it's back on the prowl :)