Ugh.... No Boost.... AGAIN!!!!! - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


Forced Induction All questions and problems regarding Superchargers, Turbos, NOS, ZEX, intercoolers, water injection, etc.

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Old 08-11-2004, 12:23 PM   #1
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Default Ugh.... No Boost.... AGAIN!!!!!

Ok... the car (97) has been sitting for around 2 weeks while I've been enjoying the 91.
Today I dropped the 91 off at the mechanic and got in the 97.
First thing I noticed was she was sluggish off the line... I looked at my boost... it only goes upto ZERO and then stops. I scanned the car but only found a code for Evap Emissions (see my other thread).
I'm thinking bad BCS again, but it was just replaced less then 4 months ago..... ARG!!!

Is there anyway to test/run the car w/o using the BCS?
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Old 08-11-2004, 12:29 PM   #2
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Without using the BCS? There'* the Bypass trick that some people do. There are stickies here for that.

If you pull the plug out of it you're only going to run ~ 2psi MAX. So check your connections.
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Old 08-11-2004, 12:38 PM   #3
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Quote:
Originally Posted by BonneMeMN
Without using the BCS? There'* the Bypass trick that some people do. There are stickies here for that.

If you pull the plug out of it you're only going to run ~ 2psi MAX. So check your connections.
I think the bypass trick is only for building up boost really quickly.
I'm going to wait for the engine to cool, and then take another look around.
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Old 08-11-2004, 12:59 PM   #4
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The bypass just disallows the PCM from dictating boost. If it'* a sensor or PCM problem, that would get you boost back.

With the Evap and boost both being bad right now, I'd be looking for a vacuum leak somewhere. It'* the common factor.
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Old 08-11-2004, 03:51 PM   #5
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Quote:
Originally Posted by willwren
The bypass just disallows the PCM from dictating boost. If it'* a sensor or PCM problem, that would get you boost back.

With the Evap and boost both being bad right now, I'd be looking for a vacuum leak somewhere. It'* the common factor.
I searched for the bypass.... got a link to the thread?

Where would I start to look for a vacuum leak?
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Old 08-11-2004, 04:54 PM   #6
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Do a search on "boost bypass" in forced induction AND suggestions. Search for all terms.

The first place I'd check for vacuum leaks is the top of the Supercharger where it all comes from, and the vacuum manifold on the firewall, just to the left of the WS wiper motor as you face the engine. Black box, looks like part of the maxifuse relay center.

Does your climate control work fine?
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Old 08-11-2004, 05:44 PM   #7
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Yea the climate control works fine. Jen had the AC going when I got in the car.
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Old 08-11-2004, 06:06 PM   #8
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Comes out the right vents?
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Old 08-11-2004, 08:17 PM   #9
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Quote:
Originally Posted by willwren
Comes out the right vents?
Hrm... not sure about that... I'll check later.
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Old 08-11-2004, 08:30 PM   #10
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It'd be nice if you had a tiny camera you could put under the hood to see if the BCS is closing the valve all the way..hrm...Maybe put something, like foil, on the stopper nut and let a flap of it stick up so that when the BCS closes the valve it'll crush the piece of foil. That way you can tell if its moving all the way or at what point it stops. You might need something more stable than foil (or use a thick/wrapped piece) to hold up to the wind. Meh, the idea is there.

10psi is quite a bit of vacuum leak! haha. I had one of my hoses disconnected and I still got nearly full boost but I might be a freak. If you're leaking that much you should probably hear it.
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