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

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.

Its really bad for the blower to be under boost at all times. Puts a lot of extra strain on it. If you want to be in boost just hit the pedal a bit more. In order to run in boost all the time you'd need to completely retune.

even if you could completely close the bypass, you would still not always be in boost b/c the rpms of the blower would not be enough.
do you feel like you dont have enough low end now?
you need more mods, not more boost.

Can imagine the MPG figures with boost applied 100% of the time? 5 MPG if you're lucky.

It's about efficiency. Bypassing the SC when not needed keeps the intake air temps cooler, less strain on the SC overall and less energy wasted through parasitic losses. It's also much harder to keep in tune. When you start getting into 'boost' via the bypass valve, it's pretty quick, and doesn't take much throttle to get there.

Don't do the 'boost bypass valve mod'. It will cause boost before the timing table is ready for it and you'll get a lot of partial throttle knock, although it may 'feel' more responsive, that's crap. Just step on the pedal more if you want to go faster. I went the opposite way - I slid the BBV as far away as it would go, so my boost comes in later. With the smaller pulley I think this helps with efficiency, plus I have since retuned my complete system, fuel and timing tables.

AA wrote:

Can imagine the MPG figures with boost applied 100% of the time? 5 MPG if you're lucky.

wow never thought about this... My MPG really had gone down alot when i did that..it was before my 3.4 inch pulley.....

I put new valve cover gaskets on and the Bypass Valve Actuator broke. A tube connection snapped off.

I know what the part is, but I'VE NO IDEA what damned part number is so I can search for it online! Any idea what they cost??

I've emailed Ed Morad for a replacement...but I'd sure like to know for myself!

Anyone???

Have you tried rockauto.com ? You can search w/o the part #, then if it's available there's usually an AC Delco number shown too.

Try P/N 1997244 for 96-99
www.monsterpartsonline.com shows them for less than $25.00

I'm not 100% sure that is it because it doesn't allow you to see the part. But that is the P/N i have on file.

The book I have gives me this part number and MonsterParts shows this for it …

Item Number....MSRP....Core Price....Price
1997244.........$42.31....$0.00...........$24.36
Fuel system - Fuel induction - Supercharger - By-pass valve
By-pass valve, all models 1996

There is no illustration so I can’t be absolutely sure though?

just glue that piece or any piece that you can find at the help section of your auto parts store. use quick set jb weld. that will work