battling compressure surge
 

ok so i have a bnr stage 4, big front mount, greddy type-s bov. ive got my adjustment nut on the greddy as soft as it can get. when im driving around normal not boosting. it will also let pressure out. but when i start boosting around 5-6 psi it will surge. is the type-s not enough for a bnr stage 4? my vaccum source for the bov is coming just from the left of where the bac valve used to be. this is decitaded to the bov no Tee. any comments?

Connect your vacuum line to one of the throttle body nipples. The nipples at the BAC only lead to one rotor so the throttle body will provide a much stronger vacuum signal.

ok im either an idiot or that doesnt make sense.

in vaccum the bov lets off fine. when above 6 psi i get compressor surge.

what would be the difference?

More pressure for the diaphram to overcome...Which may or may not be true because I don't know the exact construction of the Greddy BOVs. I've just always had issues when connecting BOVs to that vacuum nipple...Also, where is the BOV located?

about 1 foot away from the turbo

any other comments. i was hoping jrat would chime seeing as he used to run this same turbo.

I had problems with an Apexi BOV using the small vacuum nipples. Small being the ones that feed the boost sensor and such.

I had Final Victory when I went to the approx 5/16 inch nipple that is located just inline with the rear of the BAC and was originally used as a path b/t the Air Supply Solenoid and the manifold. Like I said, approx 5/16 diameter nipple. Works fine.

That was on a SERIES FOUR car.

Man, they sure did mess up on the series five engines. On the series FOUR the BAC is fed by Both of the middle *runners*. Tsk, tsk. First plastic suspension parts and now the BAC only fed by one runner.

im series 5. so you think i should try it one of the throttle body nipples. right now i have all 3 being used. the middle is going to the microtech. the top is going to the boost gauge. the bottom is going to a greddy profec b.

light compressor surge on moderate boost(3-5PSI) is relatively normal, mine only does it in that small window of pressure and grew to accept it as normal even with a large nipple on the SSQV and locating the vacuum line to the BOV as low on the manifold as possible(stock BOV port location).

I was under the impression that your BOV should be close to the TB

Just curious. Those three nipples, where are they located????? On the front or rear of the throttle body? Or????????

Just asking because not all nipples on the throttle body are VACUUM. Some are just filtered air that comes from the front of the throttle plates.

^the ones that are on the front of the throttle body (pointing towards the alt)

The top two go to the Purge valve. You know, that black plastic outfit.

The bottom one goes to the feed vacuum to two solenoids on the vacuum rack.

One of the two that go to the Purge valve, IS NOT a source of vacuum.

Page F2-6 of the online series five FSM shows in general what the nipples on the throttle body do in life.

EDIT: Not that it matters much, but that dwg has a flaw. It mislables the Switching and Relief solenoids. It shows the Relief solenoid getting vacuum when we all know it does not ever get vacuum on a Turbo car.

First the flaw in the wiring diagrams I found a couple of days ago and now this. Where will it all end. humor.

you know you are a car nerd when you start correcting factory service manuals

update
ok so this is how its run i forgot that the last shop i took it too ran the vaccum different. this how he suggest and i trust him. scott with mazsport here in florida.

the left of the bac valve goes to my boost gauge and EBC

the ones on the front of the throttle body go like this

the middle goes to the bov
the bottom goes the microtech
the top goes to the aftermarket fpr

i turned the bov as loose as it will go and still am getting compressor surge anything over 3 psi.

bump, ive done some reading and i read that if i hook up the bottom nipple on the greddy type-s to a pressure source ( before the throttle body) that it would help with reaction time of the bov. is this true? would i have to make my own nipple in my FMIC piping?