FAQ: Boost Bypass Valve/Boost Control Solenoid Questions (No Boost)

have not done anything with it its been shitty out so i have not been drivin it

Today I hooked up boost gauge and so it was, no boost. Max 3psi at WOT!

I suspect control solenoid, but I would appreciate tips on troubleshooting.

In the picture below is control solenoid, and one port is open, WHY? May it be the culprit? Please help!



The car is 1997 Riviera.

Btw, I already replaced supercharger coupler and nose bearings, and I hear supercharger whine at WOT, so its not stuck or anything. I also checked that boost valve is moving, when I start the car.

that port should be open. and it is suposed to have a little filter on it but w/e.
still sounds like it could be the control valve or a vac line. does the arm on the BBV fully open/close?

mine did that the other day.
dont know what it was. Just chalked it up to the PCM cutting boost off because of a fueling problem. Normal boost now.

Well, I checked that BBV lever is going up when car is started and when it shut down, lever resting on intake plenum. So it is moving.

What's the good place to shop around for new boost control solenoid? I checked rockauto.com but they doesn't seem to have one...

Find one from other members for $10-15. GM wants about $30-40 IIRC.

mine is only getting about 7psi at WOT

is my BCS going out? Or do you really lose that much boost with a ported SC?

Well, 7psi would be normal. According to 1997 Riviera/Aurora shop manual it should be around 7-9psi, so its ok. Mine is only about 2-3psi at WOT, so its not charging. My PA Ultra is Series I SC engine, and it feels much more quicker than 97 Riv with Series II SC motor, because of low boost.


I tried to eliminate bypass solenoid and even disconnected vacuum line from bypass valve, but its still 2-3psi. I'm hearing some "hissing" sound maybe from under blower, I guess it may be faulty plenum to supercharger gasket or something? I dunno yet.

is the vac line under the blower snout connected?

arttu80 wrote:

Well, 7psi would be normal. According to 1997 Riviera/Aurora shop manual it should be around 7-9psi, so its ok. Mine is only about 2-3psi at WOT, so its not charging. My PA Ultra is Series I SC engine, and it feels much more quicker than 97 Riv with Series II SC motor, because of low boost.


I tried to eliminate bypass solenoid and even disconnected vacuum line from bypass valve, but its still 2-3psi. I'm hearing some "hissing" sound maybe from under blower, I guess it may be faulty plenum to supercharger gasket or something? I dunno yet.

well 7-9 is normal for a 3.8 pulley on a stock motor. I got a 3.25" Sorry, didn't mean to hijack your thread. What was the theory behind bypassing the BCS?

Mr.Riviera wrote:

is the vac line under the blower snout connected?

yes. All my vac lines now run from that one port since I got the newer type SC housing.

Quote :

Well, 7psi would be normal. According to 1997 Riviera/Aurora shop manual it should be around 7-9psi, so its ok.

Yes, but drew is running a 3.25" pulley and some other mods, so I think 7 PSI is pretty low. I normally hit 11-12 with a 3.4" pulley. 14-15 PSI with a 3.2".

so any thoughts?
is missing half my boost enough to suspect the BBV or BCS as culprit? Or is it something else?

dreww wrote:

so any thoughts?
is missing half my boost enough to suspect the BBV or BCS as culprit? Or is it something else?

It happend to me. Bypass the BCS to be sure.

oldsman105 wrote:

dreww wrote:

so any thoughts?
is missing half my boost enough to suspect the BBV or BCS as culprit? Or is it something else?

It happend to me. Bypass the BCS to be sure.

I bypassed the BCS and it doesnt make a difference. The BBV is opening fully, and now Im getting max 1.6psi I just know if I start replacing all those parts it still wont fix the problem and will make we wanna drive her off a cliff.

oh, and also got a vac leak somewhere now (LTFT 16.4) and I cant hear it anywhere. ALL vac lines are new. I dont even know where to go from here.

Anyone know, where I can get supercharger-to-intake gasket??

arttu80 wrote:

Anyone know, where I can get supercharger-to-intake gasket??

http://www.zzperformance.com/grand_prix/products1.php?id=306&catid=103

dont forget the o-rings too.

http://www.zzperformance.com/grand_prix/products1.php?id=305&catid=103

dreww wrote:

oldsman105 wrote:

dreww wrote:

so any thoughts?
is missing half my boost enough to suspect the BBV or BCS as culprit? Or is it something else?

It happend to me. Bypass the BCS to be sure.

I bypassed the BCS and it doesnt make a difference. The BBV is opening fully, and now Im getting max 1.6psi I just know if I start replacing all those parts it still wont fix the problem and will make we wanna drive her off a cliff.

oh, and also got a vac leak somewhere now (LTFT 16.4) and I cant hear it anywhere. ALL vac lines are new. I dont even know where to go from here.

So how did you bypass the BCS oldsman? I tried it (but dont know if I did it correctly) and the problem remained. I re-tightened the SC bolts and about half were a little loose (1/4-1/2 turn) but that still didn't fix the problem. Got a new BBV Im gonna test today but dont think it will fix the problem since the old one seemed to be working fine (but was ghetto patched with JB weld)

Sure way to check the BBV, physically brace it shut (down) at the flat swinging lever with a block of wood or something. If it makes boost at that point, the BBV or something that controls it is malfuntioning. If you don't get your boost, then the vac leak must be pretty bad or theres another problem entirely

turtleman wrote:

Sure way to check the BBV, physically brace it shut (down) at the flat swinging lever with a block of wood or something. If it makes boost at that point, the BBV or something that controls it is malfuntioning. If you don't get your boost, then the vac leak must be pretty bad or theres another problem entirely

well my new BBV didn't fix the problem though it did need replacing as its been broke since I got the car. Now Im getting 2psi at WOT so its looking more like the BCS.

I think I finally figured out how to bypass it. And will check the ohms on it to to see if its functioning or not.

Is it possible to block the bypass in the S/C so that it runs under boost at all times?

Would this damage the engine, or is it just a way to keep the mpg up?

It seems that running most of the time in a N/A mode kind of defeats the purpose of having a supercharged engine in the first place.

What do you think?

EASHER wrote:

Is it possible to block the bypass in the S/C so that it runs under boost at all times?

Would this damage the engine, or is it just a way to keep the mpg up?

It seems that running most of the time in a N/A mode kind of defeats the purpose of having a supercharged engine in the first place.

What do you think?

There is a BBV mod that you can do to make it boost QUICKER.... I did it and noticed a LITTLE BIT... its a FREE mod so Search it... under Free Boost Bypass Valve mod

Series I thread:

https://rivperformance.editboard.com/series-i-engine-transmission-f13/boost-bypass-valve-mod-t177.htm

ive read that this mod increases knock at mid level rpm and the poster swore that should not be done. the gains are very minimal and really dont seem to be worth the extra chance of knock where there used to be none

I did that already. I was wondering if it is possible to completely eliminate the bypass function and have the engine under boost at all times.

Im still fairly new to the whole 'boost' thing- but that sounds bad to me. Why would u want boost when its not needed ie. idle.