quik1

I just got a used JRSC and noticed that the air bypass valve has a rip in the diafram. My question is what exactly does this do and do I definetly need a new one for it to run. New ones are $300 and I don't have that kind of cash right now. I'm in the middle of this install and need to know if I should keep going or put the stock stuff back on. TIA

sharkcohen

The bypass valve recirculates the pumped air when the engine is running under vacuum so you aren't in boost at idle and part throttle/low load. If it is damaged it won't work correctly. You need a new one.

quik1

Will the car still run? What happends if you are in boost at idle? I'm guessing it won't be high boost. Can it damage anything?

kobi2002

I would have to disagree on that. Once upon a time I to had a jrsc and my bypass valve ripped causing a vacuum leak. I disco the line which leaves it closed and it did not boost at idle or part. I wondered what it really was used for since the performace did not change at all. boost only hits at wot or when there is a load, but regular driving did not change so your answer is I think you will be fine. I ended up selling my kit and went turbo and the guy that has it now still drives it with a ripped bypass value.

quik1

Cool thats what I want to hear.

dutchmikkel

i did try running without but it gave me a error on the ecu the probleem is that under idle the bypass is open and under boost its closed, so the there will be a lambda problem i think

quik1

I was just thinking about this again and wouldn't it work properly even with the rip in it cuz under a vacuum situation it would either open the valve using the diaphragm or it would suck air through the rip. The only problem would be that I would have a vacuum leak. Let me just see to make sure I understand this properly, when idle the vacume will pull the diaphragm then open the bypass valve.Is that correct?

sharkcohen

Engine vacuum holds the bypass valve open to recirculate the air, as I stated above. When the throttle is opened and engine vacuum drops, the valve closes, the air stops circulating, and the aspiration crosses over to boost.

quik1

I put the supercharger in and everything seems fine no codes and the valve does open and close. I guess the rip wasn't big enough to cause that much of a problem. Thanks you guys for all your help.