1985-1998 [Subscribe to Daily Digest] |
I must be having a brain-fart, but for some reason, I just cannot seem to understand exactly how the BPV works.
The reason I am asking is because last year I installed a piston-style one (Hyperboost by Stratmosphere), and have been plagued with turbo lag ever since. I did this because I felt with my Stage 3 ECU allowing the turbo to put out much higher boost than the stock BPV (Bosch # ending in 103) could handle, it was necessary.
In speaking with Stratmosphere, they recommended that I stretch the internal spring to lengthen it to "pre-load" the valve to avoid the lag. It seems these things are built according to Audi specs, and Saab's must create much higher vacuum at idle. I've done that, and it did get rid of some of the lag, but not all of it. Now, the boost gauge does not pin itself into the red area as it did when I first installed the Hyperboost w/o modifying the spring, and I'm thinking this is because the spring now has higher tension on it from stretching it.
So, at idle, there is vacuum present which pulls ("sucks") on the BPV, opening it up. I assume this lets the boost bleed into the air delivery system.
At load (while driving), there is boost. Does this mean there is air being blown into the valve (as opposed to pulling on it), thus closing it and allowing the full boost to be forced into the intake area? At what point does the valve start to re-open, to allow boost to bleed into the air delivery system to avoid overboost? If the spring does have more tension on it from stretching it, won't this work against the way the valve should be operating?
Is my thinking correct on how the BPV works? If not, please inform me.
TIA
Joe
'98 67K
posted by 12.111.48...
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