supercharger boost bypass valve

SuperCoupeSC91

Registered User
how often doe this go bad ? or when should u replace this ? i think i seen a member listed with a bosch one ? also if i was to call autozone to see if they have one what would i call it ? a supercharger bypass valve ? anyone change theres ? any brands i should go for ? mine is orig and i want to buy a new one if i can. trying to eliminate my vac idle of 10-11 in ....Thanks Alex L
 
The only thing that can go bad that I can think of is the bypass valve actuator, which is the vacuum pod that operates the arm that closes the valve. There is a stop screw on the plenum that you can adjust that will limit how much the valve closes. You can see it where the arm rests against the plenum with the car off. If you turn the screw out sometimes it will allow the valve to close more. Does that make sense?
 
SuperCoupeSC91 said:
how often doe this go bad ? or when should u replace this ? i think i seen a member listed with a bosch one ? also if i was to call autozone to see if they have one what would i call it ? a supercharger bypass valve ? anyone change theres ? any brands i should go for ? mine is orig and i want to buy a new one if i can. trying to eliminate my vac idle of 10-11 in ....Thanks Alex L

Alex.......your SC bypass valve is probably not causing the 10-11" vacuum idle problem. At idle the BPV is held open by high manifold vacuum. When the vacuum decreases by opening the throttle, the spring in the BPV actuator closes the BPV to increase the boost pressure. The only vacuum leak you would have on the BPV is if the actuator diaphram is ruptured. You can easily check to see if this is the source of the 10-11" vacuum problem by pullung the vacuum line off the BPV actuator and plug the line. If you still have the 10-11" vacuum leak then your BPV is good and the vacuum leak is elsewhere. If the 10-11" vacuum problem goes away, buy a new valve.

Hope this helps!

Ed Springer

90 Black XR7 5-speed: 70mm TB, Fresh Air Intake, '94 Supercharger, 5% SC Pulley, Raised SC Top, I/C Fan, Under-drive Pulleys, 190 l/h Fuel Pump, 36# Injectors, Headers, Magnaflow Muffler (no cats) with stock resonators, 3:27 Gears, Ripper Shifter, 73mm CL MAF (Blue Tube), Magnacore Wires, NGK Iridium Plugs, Royal Purple Lubricants and Rear Spring Air Bags.

94 Red SC Auto: 70mm TB, Fresh Air Intake, Stock 90 SC Pulley, Raised SC Top, I/C Fan, Under-drive Pulleys, 190 l/h Fuel Pump, 38# Injectors, Headers, Raven Muffler (no cats) with stock resonators, 3:73 Gears, 76mm CL MAF (Gold Tube), Magnacore Wires, NGK Iridium Plugs, Royal Purple Lubricants, TRANSGO Shift Kit, Pro-Torque 2500 Stall TC, Haydon Auxiliary Transmission Cooler, Tokico Struts & Shocks, American Racing 17” Sniper Wheels, Michelin Pilot Sport A/S Tires and 235 RWHP with 315 LB-FT Torque.
 
thanks guys i'll try to pull out the vac hose and plug the end ? but witch end the hose end or the BVP end ? i'll try it....thanks Alex L
 
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