I seem to have lost boost if I SLOWLY rev up the engine

If I hit the gas hard all seems OK

This is true at rest or in motion

Reading the posts am I a candidate for bypass valve replacement ? adjustment.

I did do a VGS mod and will check that as well.

Just looking for some direction

 

Its doing its job,

The bypass will open up and release boost back into the intake if your not throttling in fast.

Get a boost gauge and see what i mean.

 

Thanks ...but

I have a boost gauge ... thats how I know (not only by feel) that something is up

at rest if I very slowly rev up NO bost is shown at 5K + RPM
Jump on it and I boost to 15 lbs +

in motion jumping on it gives boost as above
If I very slowly gas it i get NONE than about 5 lbs, then it drops off, then boost again.

This is NOT how it userd to be

I also get a high pitch whistle.

THINKING VAC LEAK

Do bypass valves go bad or usually adjustment ???

 

Thats exactly how mine has always acted.

Seems completely normal to me.

 

That is how it works. Throttle position controls the amount of air that the sc can use to make boost. No air. no boost. It is more so with the bypass valve. You need low vacuum before the sc to close the bypass valve which inturn provides more air to the sc. The bypass valve is there to keep the engine running naturally aspirated as long as possible until you request power with full throttle. One more thing, at part throttle, as you feed the engne boost the rpm will go up and require more air to maintain a specific boost level. You must feed the beast.

This is why the vgs, ryephile fix, or just zip tying the valve shut will give better throttle response and more boost at specific throttle positions.