Replaced my bypass valve today with the OEM updated version with the stiffer spring. Went to start it after I had buttoned it up and the car flares more than usual on first start, as if I held the accelerator a little. The supercharger is also quite a bit louder and it tries to idle around 1500 RPM, pulsing every 2 seconds or so up to 1700 and back down. I thought I didn't seal the intercooler correctly as I've heard how insanely loud and high pitched the car gets if you start it with the intercooler off. I've now taken out and reinstalled the intercooler 3 times with the same issue. As far as I can see all intake hoses are connected and the throttle body electrical connection is secure. Could my bypass valve be causing this? During this fast idle its doing, I can see the plunger moving a bit with the RPMs, though it never pulls all the way in to completely open the valve. I can actually wiggle the plunger and can feel some slack in it. When I manually push it in all the way, the supercharger gets a little quieter but it still idles fast. No lights on the dash. What have I done? Anyone have any issues with this? I really can't afford to have this car out of service.

 

I had a simialr issue happen to me when I replaced my bypass valve a few years ago. In my case the car idled faster, was way louder and threw a code (can't remember what it was. In my case, I had accidently disconnected the Supercharger Charge Pipe Vacuum Duct where it connects to the supercharger via that big green gasket. I had accidently snapped the the plastic screw loop (see image below) that secures the duct to the supercharger when installing the new BPV.



This resulted in the duct coming loose from the supercharger and creating a big vacuum leak causing high idle, noise and error code. Had to disassemble everything as if I was pulling the BPV again, repaired the plastic loop, buttoned everything back up and car ran fine.

Hope this helps.

 

Need to make sure all your hose/duct connections are tight. On a new part, remember that just because it is in a new box and sold as new, it does always mean it is going to work like new.

 

Thanks for your thoughts folks. I hope I didn’t mess up the supercharger intake duct; heard bad things about that green gasket. Can you even access the screw from the top without putting it in service mode? I’m probably going to try misting some water over the throttle body area after work today to see if I can tell where it’s sucking air. It doesn’t sound like it’s coming from the supercharger/intercooler area, more like the space between the intercooler and the air box behind the throttle body.

What about the throttle body? Pretty foolproof putting that back on, no? I know the supercharger duct has locating dowels on it to accept the throttle body, maybe I didn’t seat those correctly?

 

Check your intercooler boots, make sure they are on correctly and tight.

Check the bypass hose for cracks, if it was hard as a rock then you need to replace it.

 

I’ve reinstalled the intercooler 3 times and made sure the boots were even around the intercooler lips. The boots don’t look damaged. The bypass hose was pretty hard, but I know I tightened the clamps and so I don’t think it could cause a vacuum leak this bad. I’ll certainly check again if I have to take everything back out.

 

So I found the problem but I'm having trouble fixing it. The vacuum line that feeds to the MAP sensor pulled out of the supercharger duct. But all the information I can find online shows the red retaining clip attached to the supercharger duct with the hose itself pulled out of the retainer. In my case, the entire retainer pulled out of the duct with the vacuum line still attached. Nothing appears to be broken, but I can't for the life of me force the retainer back into the duct. Is there a special technique to this or do I need to release the retainer from the vacuum line first or something? Not much room to work in either.

 

Not sure where you are at with this, but whatever you do, don't force it...
Maybe a pic to see what you are looking at?

This YouTube video shows the technique of working with the now famous "Red Clip."

 

I got it. Just needed to figure out a way to get both hands in there. Everything back to normal.

 

Sweet. Glad you were able to find the issue and fix it. Motor on.