Second boost?

Hi guys my 1996 supercharged is acting funny I think. So if I floor it in first gear, I will accelerate quickly as normal but around 4k to 4500k rpm the car just jerks forward like it got 50 horsepower gain right there, it is very weird and cool, but is it normal? Cause I know these cars don't have vtec;) I was think it could be my serpentine belt slipping maybe?

It's stock, everything I've done to is in my signature, I mean it's random, sometimes it doesn't hit vtec, then it does, so idk. I like it when it doesn't tho I have way more power in the low end. If you think it's the tranny then I'm flushing the fluid in 2 weeks so we'll see, I'm also getting new belts so maybe that would fix it.

Try turning off the traction control. See if it still does it.

Yah it still does it, But my belts have never been changed so I was thinking the belt was slipping then catching around that rpm. What other possibilities?

Vtec just kicked in yo! Hope your trans isnt slipping. Anything else different with your since you've noticed the boost?

So is this behavior different than it used to be? It's not the trans shifting from 1st to 2nd? If your trans is stock, I wouldn't think it would "jerk" exactly, during that shift.

Oh and just so you guys are aware when I floored it with the boost guage tonight and vtec kicked in again, the boost didn't change so I guess that's something new.

So it still does it, I notice this started happening when I installed my intake, I plugged my sensor in and put it as close as I could to the intake, but if this sensor is damaged could that be the case?

The sensor looks fine to me I'm just wondering cause I want my low end torque back

I would try putting your factory intake back in. If it fixes it, something was wrong with your intake setup.

Ok I'm gonna do that then. I'll keep you posted

Today i installed a boost gauge. when i tested it, i floored it and read 4 pounds then around 5krpm it topped out a 5psi. then when i drove it around some more, i hear the supercharger whine, but read 0psi then around 4500k rpm my boost gauge shoots up to 4psi and i feel a huge kick like vtec lol. this has been happening for a couple months even before the boost gauge, i just didn't know what the car was doing till i added the gauge. i also hear my supercharger snout hissing so i know there a vacuum leak somewhere around there but i don't think thats why my car is acting like this. I've sprayed starter fluid all around the hissing and no revv to.

Any way you could take a video of whats happening?

Yes give me 10 min

I'm gonna send it to you threw email Dave I just have a phone so I can't up load it to this website

bmcd9179 wrote:

I'm gonna send it to you threw email Dave I just have a phone so I can't up load it to this website

Im not really sure. Im not seeing the V-Tec thing you're talking about, the car just pulls harder up top because theres less load. Your boost numbers do seem low though. The car seems a little sluggish, kind of like if the boost bypass actuator was not working? Have you checked to see that its opening and closing properly?

I will check that, could that vtec thing, be because of the bypass actuator?

It would certainly make the car react differently to load, as in it would be especially sluggish at lower RPMs.

After investigation it is really messed up I'm going to create a video and send it to you, this has been messed with badly by the guy before me..

So where could I get a new actuator? Would the pontiac gtp ones work off of ebay?

Well, I would say thats certainly your problem man! Its hard to tell with how dark it is exactly how its broken off but its supposed to be bolted to the supercharger so the actuator can close the boost bypass valve all the way. Without that, you're losing alot of boost and its gonna slow the car down drastically. My boost bypass valve stopped working last year. As far as I know, you cant fix them and you'll just have to grab a new one from a junkyard or something. Theres always a few M90s at the U Pull It yard by me so it shouldnt be too hard to find one.

These are the best pictures I could find of how its supposed to look on the car of a series 2:





If I get a chance tomorrow, Ill pull the Riv out and take a video of what the actuator does when its working and how to tell if one is bad (not sealing fully).

And yeah, any Gen 3 M90 one would work for you. Heres the cars that had the Series 2 L67:
1997.5–2004 Buick Regal GS / GSE / GSX (SLP)
1996–1999 Buick Riviera (optional 1996-97, std. 1998-99)
2004–2005 Chevrolet Impala SS
2004–2005 Chevrolet Monte Carlo SS Supercharged/Intimidator SS
1996–1999 Oldsmobile Eighty-Eight LSS (limited)
1996–2003 Pontiac Bonneville SSEi
1997–2003 Pontiac Grand Prix GTP / GTX (SLP)

I just bought a new one but yah how does it bolt on it looks like Im missing something that is keeping it still, also the vacuum lines to it are destroyed so yah I just bought a new one. Ill email you another video tomorrow when it's day light

Just out of curiosity, would one off of a Gen V work? I wouldn't expect it to give you any gains though.

Gen 4?

So I bought my new one, it's the exact one that fits, it bolts right on and I join up my vacuum lines, so wish me luck, I'll still send u a video on how bad it's messed up..

matt270avian wrote:

Just out of curiosity, would one off of a Gen V work? I wouldn't expect it to give you any gains though.

Turtleman experimented with that in this thread:

https://rivperformance.editboard.com/t2083p90-faq-boost-bypass-valve-boost-control-solenoid-questions-no-boost?highlight=boost+bypass+actuator

BTW the '96 has a very different vacuum line and routing than the '98, not sure what's in the '97. Just make sure you are referencing another '96. I believe the BBV (Boost Bypass Valve) is the same on all the Gen 3 blowers, not sure if the Gen V has the same valve. I would expect it to be the same but have no way to verify.

Make sure there aren't any vacuum leaks. Make really really sure.

It wouldn't hurt to test the valve with a vacuum pump. There is also an exhaust valve and electric actuator in it, make sure the wire is hooked up. That one wire on the BBV is the only electrical difference between an SC motor and an NA motor.

I have a vacuum leak, both the wires connect in to the bypass are broken off so I got a whole new actuator