Mrod1012

so my buddy and I went and looked at a 2003 mustang gt with a V1 on it. It's intercooled nd has the mondo bypass valve. The valve vents to the atmosphere which is all good but, the vacuum line that runs from the top of the bypass valve isn't connected to anything.... The vacuum line just sit under the Intake tube. It's as if its not needed and just hasn't been taken of. The car runs fine and drives even better. Anyone ever seen this? The vacuum line from the bypass valve not connected to anything when vented to the atmosphere? Wondering it's that ok.

svt96cobra

That line should be hooked up in order to make the bypass valve work if im not mistaken

Mrod1012

I thought the same thing, BUT the valve works fine. When the car gets to 2 and a half 3k RPM you can hear the bypass letting the air out. When you're crusing you can hear the bypass making that whistling sound. So I don't get how it's possible for for it to work.

uberstang1

When you go WOT the valve should be shut, as in NOT letting air out.

Mrod1012

Ok so we went back and this time I drove the car. I connected the the vacuum line to where the previous owner had it connected and then decided to cap. I got under the car and felt the bypass valve blowing air out. It wasn't blowing air out when the line was pulled. I then drove the car with line pulled and lie hooked up. When the line was hooked up the car would get boost to the motor but when you let off the gas you got the flutter sound coming from the blower. I'm assuming that's what my buddy thought was the bypass letting air out. I then connected the vacuum line and the car didn't pull good at all. It wouldn't even go into boost. I'm assuming it's because the valve is open at WOT when it should be closed. Also, at idle when the vacuum line is connected the idle jumps and when i drive it around the car feels like it jumps a little. I'm think the bypass vlave might need adjusting...what do you guys think? Any input would be greatly appreciated.

school boy

is there a second hookup on the bypass valve?

Mrod1012

By second hook up do you mean the little nipple looking thing at the bottom of the bypass valve

Frostbitten

with a bypass valve there should only be one connection. it should be connected to the intake manifold itself, not the boost pipes. if yours is having issues then it might be sticking open. that may be why the previous owner unhooked it. the car will run like that, but it causes extreme compressor surge which could blow the seals inside the blower. i would remove the valve, take it apart, and clean it out with some wd40

dwtjr3

Sounds to me like compressor surge,

Mrod1012

Yea I thought the same compressor surge. I told my buddy its probably the tune because at idle the cars RPM jump a little. So of he decides to buy it he'll have to get the tune checked out.