Hissing Coming From Intake/turbo When On Throttle

[djvoodoo]

Hey fellow SAU readers. This is my first post so please be kind... No flameage please..

Car is a 99 R34

Only mods are full 3" Jasma approved exhaust, Greddy profec II Lo-8psi Hi-11psi (stock r34 turbo)

Last weekend I installed a return flow IC (Coolingpro) from Justjap, suprisingly did not have to chop at reo bars or front bumper.. anyway.

Car was boosting perfectly, idle perfect, no leaks, power came on smooth and delivery was better than with the standard SMIC.

On sunday I was travelling home and all of a sudden it felt like the car was going into R&R/limp mode and there is now a very noticeable hissing/almost screamer pipe style noise when on the throttle. Power has noticeably decreased and becomes jerky across entire rev range.

Issue is

1. Car is still boosting fine all the way to 11psi

2. Have rechecked and re-installed cooler to make sure no leaks

3.Have checked for noises on exhaust gaskets/turbo to manifold/ dump pipes etc and can't find anything

4. Have re-installed standard SMIC

5. Car not blowing white smoke, can't smell oil and turbo is boosting normally so I don't think it's blown

6. Checked rubber hose to turbo intake- no leaks

I have also takin the car to Autosport engineering in Sydney for a quick 5min inspection

Greg at Autosport thinks it may have something to do with a leak on the intake delivery, but I've checked everything with a fine tooth comb....

Vacuum leak perhaps????? Blocked cat???

the intake hiss is much more louder than normal and doesn't seem right at all.

cheers

dave

[paulr33]

vac leak, check all the vac lines for any splits or cracks in the rubber

take each end off and visually check it all around where it is cut

the old rubber vac lines are notorious for leaking / splitting when cut and are the old rubber factory items / vac lines

[djvoodoo]

vac leak, check all the vac lines for any splits or cracks in the rubber

take each end off and visually check it all around where it is cut

the old rubber vac lines are notorious for leaking / splitting when cut and are the old rubber factory items / vac lines

Yes, such a pain in the arse!! But i spose i knew I would have had to do that.. What about the standard BOV leaking? I'll try block Bov also and see what happens

[paulr33]

it leaks on idle as designed, but it shouldnt hiss flat out

ie you wouldnt hear it leak unless the vac lines are toast

[djvoodoo]

it leaks on idle as designed, but it shouldnt hiss flat out

ie you wouldnt hear it leak unless the vac lines are toast

Cheers, thanks for the help. Looks like I'll be getting out the old spray bottle and soapy water....

[paulr33]

dont even bother

if its cracked, it will be split and dead obvious

just unplug each hose carefully (the vac ones) and visuaually inspect

usually they fray and split apart where its been cut

[sirjb]

Use a can of Carby Clean. Spray along the vac lines, around the intake manifold, any where it could be leaking from. When the rev's increase then you have found your leak.