normal vacuum presure at idle

[dvs-b4]

yea it will be 1 of the 2

[THUNDA]

20vac

[Guest Eastwolf]

Oh... phew, I was wrong...

the reading at "6 o'clock" is actually -0.5bar =)

It stays around there somewhere when cruising and goes further neg when engine braking.

Same as you guys.....

gawd, someone has really bad txt language above.... !

[dvs-b4]

yea sounds bout right

[Guest Eastwolf]

Boost guage is really useful to help with driving efficiency.... ie, no boost = better mileage.

[Jord]

Its pretty easy to tell when your on boost anyways though!

[dvs-b4]

haha yea it is helpfull thats y i put 1 in yea i do knw when ur on boost bt if u hit it slowly u dnt realy feel it

[Bazza-NZ]

 Bazza-NZ said:

Mine reads

Cold = -20PSI

Warm = -25PSI

Hot = -30PSI

During idle the vac changes, due to what i believe is an vac leak somewhere (i just can't find it as of yet)

NOTE - Boost guage is T'd at the BOV to manifold pipe

Just as an update i found my leak, has cracked around the BOV connection... couldn't of seen it while on the car as its underneath... but i heard it

[dvs-b4]

thats a nasty crack bt would that couse your vacuum to skyrocket like that? isnt the bpv closed untill u release the gas? so it shouldnt realy afect the vacuum? please correct me if im rong

[Bazza-NZ]

 dvs-b4 said:

thats a nasty crack bt would that couse your vacuum to skyrocket like that? isnt the bpv closed untill u release the gas? so it shouldnt realy afect the vacuum? please correct me if im rong

Well i put a temp pipe on for the mean time and it seem to have stable out the idle and is sitting back at -20 again... i think that it caused the car to run rich in which turn then made it idle funny and the changes in idle caused the different vac pressure reading...

Am waiting now till i get either a replacement or aftermarket bit before i can say for sure tho...

[dvs-b4]

ohk yea that makes a bit of sence now. people with aftermarket bovs have a big problem with that so iv herd

[Bazza-NZ]

 dvs-b4 said:

ohk yea that makes a bit of sence now. people with aftermarket bovs have a big problem with that so iv herd

Yeah, i had an aftermarket one before and i just hated it, never really worked well and when cold the car wouldn't idle right.. i reckon that the standard factory ones are good enough for my application anyways... this way the measured air gets returned back into the system instead of to atmosphere

[dvs-b4]

yea i wouldnt even think about changing the factory 1 on mine

[Bazza-NZ]

 dvs-b4 said:

yea i wouldnt even think about changing the factory 1 on mine

Yeah way too much of a hassle however i am looking at getting a GFB hybrid.. they look pretty cool and could have there use...

[dvs-b4]

yea as long as they dont stuf up the air fuel mixter

[dubbedup]

I think i have an Apexi one of them.....will have to look to be sure

[JWDRPN]

going back in time 3 years hahaha

i had my vacuum checked from my manifold yesterday and it was reading 13...

he seemed to think my cam timing was out. car feels fine cept on boost where it surges

after any advice really

[funkytown]

13in/HG?

I would be going round checking all your boost line plumbing. then take the front covers off to check cam timing after that.

[JWDRPN]

i gather so he just said to me he hooked up my manifold to a guage and it was 13 and its spose to be round 20.

so im kinda lost as to what to check.. would a leak cause it to drop that much?

[funkytown]

yup it would and yes about 19 or 20 in/HG is about what you should expect on an unlaboured idle.

[JWDRPN]

ok now a dumb question hows the best way to go about finding a leak?

[funkytown]

trace all he vac leads from the manifold, sensors, and WG across the engine bay.. check for popped hoses, cracks, or holes... fairly manual task.

Also check for any leaks from the turbo through your intercooler to the throttle body, joins often pop if you run a FMIC and you've not done one up tight enough. or a pinched joiner in a TMIC setup. (car usually runs like a bag of shit though)

What turbo / ecu / intercooler do you run and in what version car? Do you run an EWG? or an EBC or MBC?

[JWDRPN]

i have a completly dead stock 02 sti

[funkytown]

start checking i/c tract and the boost lines then

might require a bit of time pissing about, but you can easily trace them all yourself and costs you nothing.

[JWDRPN]

exactly thanks

i find it hard to beleive its cam timing as the cambelt was done 40thou ks ago...

alright im off to do some searching