Low boost

[camarokidz28]

seems to be an intermittent problem, 800 miles to my brothers, and noticed the boost was low. Changed the map sensor and didnt fix it. When I got home we swapped super chargers and still no boost. We get about 3lbs.
Normally it has about 8-9lbs.
The weird thing is that when I was down there, the boost was working for about 20 minutes, then back to nothing.

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[smug]

bypass valve might be sticking or just bad

 

[Bob Kazamakis]

Boost control solenoid maybe? I know when I didn't have mine hooked up properly it was low boost

 

[boostedguy05]

small vacuum leak when boost hits. hard to tell under normal idling. but when you hit boost the line crack open or the rubber boot opens causing the leak.

really hared to really tell. could be everything posted or one. replace the whole motor just incase.

 

[camarokidz28]

bypass valve might be sticking or just bad

I switched the supercharger so this is a different supercharger and bypass valve. But we did check that and it seemed to be opening fully

 

[camarokidz28]

small vacuum leak when boost hits. hard to tell under normal idling. but when you hit boost the line crack open or the rubber boot opens causing the leak.

really hared to really tell. could be everything posted or one. replace the whole motor just incase.

this is the replacement motor...

we redid about half the vacuum lines because we suspected a leak. I guess I will finish them off and see what happens

 

[m_dogg]

What is the average boost on unmodified car? 7.7 is what I saw in 30 deg weather. Sorry to hijack man...

 

[1quick]

if you have an egr check that also for a vacuum leak on the pipe from the intake to the egr, does it feel slow or are you just not seeing as much boost on the gauge

 

[boostedguy05]

this is the replacement motor...

we redid about half the vacuum lines because we suspected a leak. I guess I will finish them off and see what happens

but did you also replace the rubber elbows? that's where mine were leaking from.

 

[camarokidz28]

we replaced a lot of it. We swapped the boost controller just now. same result...
the only way we got full boost was to unhook the vacuum line on the supercharger side of the bypass or to unhook the vacuum from the other side of the boost controller

 

[02BlueGT]

we replaced a lot of it. We swapped the boost controller just now. same result...
the only way we got full boost was to unhook the vacuum line on the supercharger side of the bypass or to unhook the vacuum from the other side of the boost controller

Did you mix em up? Top port on the bypass vavle diaphragm (hockey puck lookin thing) goes to the top tree on the Supercharger Bottom port goes to the BBV solenoid.

Also, You can just leave the lower port open to atmosphere, that takes the computer control out of the equation. I run my car that way, full boost, no issues.

 

[camarokidz28]

Right now thats what we have, the bottom line is taken off and it seems to be running normally.

 

[camarokidz28]

What is the average boost on unmodified car? 7.7 is what I saw in 30 deg weather. Sorry to hijack man...

If you're asking me, I don't know. I've never owned a stock grand prix. Mine is currently an l26 block.

 

[Fish]

What is the average boost on unmodified car? 7.7 is what I saw in 30 deg weather. Sorry to hijack man...

Sounds about right for a gen 3 car. My gen 5 regal would see about 8.5 with a stock pulley when it was cold.

 

[Turbocharged400sbc]

Right now thats what we have, the bottom line is taken off and it seems to be running normally.

thats probably yer issue....good to leave it open to air and delete the bbv solenoid

ive seen guys plug off the bottom bbv cannister nipple and when the engine is up at operating temp the trapped air in the bottom expands and holds the bbv open...
the same thing can happen if the line that goes to the bbv solenoid is instead connected to the lower port

 

[slowchevy]

What is the average boost on unmodified car? 7.7 is what I saw in 30 deg weather. Sorry to hijack man...

dunno if it's relevant but I saw 10.7# , 10.5#~ multiple times on stock everything last night on my aeroforce.. was at -2°F

 

[ktraver97ss]

While doing coldstart burnouts?

 

[TonzKnock-G]

=

moar boost