mikeDaBike

Car I've just got has a Forge vent-to-atmosphere dump valve fitted - not sure if I'd put one on myself but quite like it now

When I start driving it takes about five minutes before it starts making it's psssh noise.

Is this normal, is it just building up a bit of pressure or should it do it from start off?

Andy McCord

AFAIK it should do it from the first amount of positive boost

mikeDaBike

In that case, could the problem just be the valve needing a clean, or something more serious?

Andy McCord

have you got a boost gauge fitted?
Are you saying that, say you rev to 5K in the first 5 mins of driving from cold you get no noise then 5 mins later when its warm it makes the noise?

[Edited by Andy McCord - 8/28/2003 11:20:59 AM]

mikeDaBike

Yes, I do have a boost guage fitted.

I try to keep revs down when the engine is cold as a matter of course so wouldn't hit 5k revs, but am just giving a little bit of boost which results in a very slight dribbly sound from the valve.

After about 5 mins the same amount of boost will produce the whoosh.

Andy McCord

I have to say its sounds weird, i would of thought that if it not dumping then it must be overboosting, i have a mate with the same valve as you fitted, i will point him at this thread to see if his does the same, either its norm or its sticking (bit of dirt got in when refitting to the I/C)

mikeDaBike

Cheers mate, that'd be appreciated

mikeDaBike

Just got an email back from Forge saying this behaviour is ok, but to let them know if anything else happens.

Gedi

could it be anything to do with the way your dv operates (diaphram, piston, other?) being more efficient when warm.

e.g. diaghram not sealing when cold and your leaking boost.
Spring operating better when warm.
Piston sicking when cold
etc...etc...

Just a thought

[Edited by Gedi - 8/28/2003 4:15:29 PM]