ItalianJoe1

iTrader: (10)

It allows whatever is in the manifold. The way it's setup, it would only open to retard boost while at WOT so it would only be boost it allows to the valve. But during normal driving it's got vacuum coming to it from the intake manifold. It would be not activated though unless the PCM is trying to limit boost.

RedLined

OK, I misunderstood. I thought you were saying that it would also allow vacuum to open the bpv. Which didn't make sense to me.

RedLined

Thought Id post theses in case anyone cared to see them.




BPV Open




BPV Closed

jdeshong

You can buy a vacuum gauge from HF for cheap to test the boost solenoid. The solenoid does only control boost but if it can't hold vacuum then it won't hold boost either. The vacuum test is just an easy way to test.

RedLined

We have one here at work so I'll probably bring it in this weekend to check everything. If it wasn't holding vacuum then wouldn't it have a vacuum leak? I've heard people say it will leak from the nipple below the one where you plug in the line to bpv. I'll check it later but I don't think I heard or felt a leak when I pulled the line.

jdeshong

No it wouldn't be a vacuum leak because the hose goes to the bypass valve and it would not be sucking unmetered air.

RedLined

If the solenoid is bad it can suck in air and cause a vacuum leak. I cant find a thread to reference here on this site but you can on the redline forums and even on an ariel atom forum.

RedLined

Just checked it and it definitely is sucking in air through that bottom nipple. Guess I need to find a new solenoid.

beast124

Glad to see this thread! I'm having a similar problem with boost..it's like it's limiting boost and seems to stay around stock 12.5-13 psi. My car is a full GMS3 car with the stage 3 pulley..it used to make about 15.5-16 psi but nowadays it boosts lower on the 93 or 100 octane tune..from previous inspection the bpv, lines solenoid etc all looked fine and checked out..the car does have an exhaust on it and ported stock header..I'm thinking it may be an ecu problem? Any reason why a GM stage tuned car would pull boost? I have the dual pass and a fairly new IC pump that works..

Thanks
John

RedLined

I believe iat temp, coolant temp, and knock will limit boost. Also traction control I think? Any of those sound like they might be causing it? I believe the stage 3 pcm is locked so I don't know if anyone has ever seen if there is a boost limit on there.

beast124

Thanks for the help! The IATs should be good cuz of the dual pass and newer IC pump..ironically it's like they were higher before the pump and after it seemed like they went down right after the install..currently I'm running in high octane mode and if it senses knock it will turn the tune off and it's been on all day..on a pull to work same thing maybe 12.5 to 13 psi tops..I was thinking maybe the filter on the CAI is really dirty? It's in the fender well..also I've considered just getting a whole new BPV and having that done to see if it would help for the heck of it..I find this very strange and even wanted to pulley down soon..anyways any other ideas or help would be greatly appreciated!

beast124

Thanks for the reply! The IATs should be good since I just had the IC pump replaced and the dual pass has been on for a while..but ironically what I noticed is before when it was broken it was boosting well over 15 psi etc..it's like after it was fixed that's when I noticed the 12-13 psi..also the knock is under control since I have the car in high octane mode currently with race gas and when it senses knock it shuts the tune off and it hasn't done since I've been running it for days..I've thought about just saying the heck with it and replace the BPV anyways and figure it couldn't hurt to really eliminate that problem..also I have the stage 2 belt..I was also planning on pulleying down as well..I'm thinking maybe the filter on my CAI is dirty or something since its in the fender well? Any other help or ideas are greatly appreciated! Thanks! 👍

beast124

Well it appears once I removed the hydro shield that gave me some boost back..so the filter is crap too..went to pep boys to get a temp filter(specter) come home and no filter! That piece of crap fell off but the car is much better! Even with the old dirty filter eclipsed 15 psi 👍

Stumpalump

I had intermittent low boost and the problem was the the butterfly shaft itself was sticking. I sprayed Triflow on the shaft so it would trickle down and free up the bushings. It took about 5 minutes of spraying and working it back and forth. It should move very freely.

beast124

Was it while it was building boost or further up the powerband?

Stumpalump

It would build to about 6. I'd pump the throttle and sometimes it would build full boost.
I had to remove the actuator and work the lube in it for a long time to free it up. It's been fine since. No electric solinoid on it or can think of any logical reason to have it other than to cut the boost when the engine is cold or overheated. Be careful if you take off the actuator to mark it and put it back where it was. You set the position and stop screew with the blower off so you can see the valve closed position. Adjust the actuator position and dial in the stop to get the butterfly to close just right but the blower needs to be off to adjust it. Mark it.

beast124

Thanks for that info if the time ever comes for me! I think mine is ok but have thought about replacing it for maintenance one of these days

Stumpalump

I would never remove it unless it is leaking. Put a long hose on it and test it by mouth or use the vac tool. You throw off the adjustment if you remove it and the best way to adjust it is with the blower off. With it off you look for light escaping the butterfly and adjust the stop so no light comes thru and it's not bottoming out hard. If it is already out of adjustment and you do not want to remove the blower then loosen the mounting bolts and retighten until it's just off of the stop. Then adjust the stop so it just barly starts to move the butterfly away from the fully closed position. Basically you don't want the butterfly to slam shut or it will wear and stick in the bore. This is generally going to be where it would be if you adjusted it with the light trick but you will never know its 100% closed or leaking unless you look at it with the blower off. The shaft should rotate with some mild force with actuator on. It should be smooth. After freeing mine up I'd recomend that everybody put a drop of oil on that shaft once in a while. To lube the bottom you go in thru the throttle body but you have to guess. Only the top bushing is a problem because it's exposed. If it is out of adjustment you loose 1-2 psi. If it's sticking you loose a lot of boost and know you have a problem right away. I can't see the electric solinoid doing anything but to keep you guessing. Mine is long gone but I'm not on a factory computer so IDK if removing one on a stock controlled car is best. I do know mine runs like a bat out of hell and has unbelievable throttle control and hit when I'm pedaling the throttle.

Stumpalump

Mark your pully and mark your belt. If they stay lined up then it's not slipping.

Lionman

Just had a question is there a setting for the by pass valve?