Problem with compression

[juffu]

hello ,
i changed my blow off on my s2 and i got bad iddle
my depresssion is about -0.6, -0.7.

my dump is a tial q 50 mm with a 11 psi spring ?

somebody has a idea ?

thks have a good day

[Greg_S]

I have tweaked the title for you as think you were asking about compression of the engine

[Acidburn]

sounds like the common issue of a vent to air dump valve throwing the maf/ecu mixture off.

[GazzaG60]

never had an issue with my GFB to atmosphere. there is monitored evidence of issues but I think the ole s2 can hack it.

sounds like its leaking on idle. make sure all pipes are connected well and maybe try to tighten the valve up a bit.

[juffu]

i check for leak and i dont found any one.
The only things that i changed before this probleme is the blow off.
so i ask to 034 motorsport and they say that this king of blow ( not recycled) can make me problems.
Somebody has alreday put a blow off not recycled on his s2 and thats works ?
what's the normal values for an s2 at iddle ?

i ran with motronic a 034 3071 management an no probleme before thaht modification

[newsh]

Title should read problems with Vacuum. It sounds like you have enough vacuum at idle to open the DV and draw in unmetered air. try a stronger spring in the DV.

Conventional wisdom here is that Motronic really wants a Recirc Valve. With a "Dump to atmosphere Valve" every time you close the throttle you lose air which has been metered by the MAF and the engine overfuels.

[newsh]

BTW, how did you plug the hole in the MAF hose?

[dunstan]

Title should read problems with Vacuum. It sounds like you have enough vacuum at idle to open the DV and draw in unmetered air. try a stronger spring in the DV.

Conventional wisdom here is that Motronic really wants a Recirc Valve. With a "Dump to atmosphere Valve" every time you close the throttle you lose air which has been metered by the MAF and the engine overfuels.

That will only make it ruch on overrun.
Does your 034 ecu have a MAP senser? If so it wont use a MAF at all any how.

Are you idling lower? a split in the DV diaphragm,or drawing unmetered air will make it idle higher.

[adam g]

Defo check the clips around the new valve first to make sure no air leaks.

Do you mean you have motronic ecu but with 034 chip?