Boost leak?

[Turbojuice]

Hey guys, I have had my boost gauge in for a while, and it has been reading a maximum of 4PSI on WOT. I am on stock WGA, no controller, no piggyback or anything.
I am running a weird exhaust though. It is a Perrin JBE with a weird midpipe with some ebay cats cut up and welded in. It is a 2" pipe. I do not know a whole bunch about FI, but I am wondering if perhaps that midpipe is reducing my boost? I am running at -20 at idle.

The thing that I am confused about though... wouldn't I see a vac leak before a boost leak?

 

[Safe Zone Msp]

Yes, you should see a vacuum leak first,unless you're leaking off the stock hot pipe to bypass valve area. It sounds like you've got A major exhaust restriction. 2 in is smaller than factory size.

Thad.

 

[Tzar177]

Yes, you should see a vacuum leak first,unless you're leaking off the stock hot pipe to bypass valve area. It sounds like you've got A major exhaust restriction. 2 in is smaller than factory size.

Thad.

2" is smaller than stock? What is stock?

 

[Turbojuice]

Stock is 2.5". That is why I noted that mine was smaller. Would the exhaust restriction lower the amount of air I can boost? It would kind of make sense because of all of the backpressure, but 2 psi lower seems like a lot. So you are thinking that it is probably not a boost leak then? Should I check my WGA? Could it be closed?

 

[Tzar177]

Is the entire stock piping 2.5"? I have stock msp turbo setup on my MP3, but with a stock MP3 midpipe, which is 1.75". I recently adjusted my stock WGA for more boost, but its still stuck at 6psi. Could my stock 1.75" piping be holding the boost back?

 

[Ricktalife]

For the record, stock MSP exhaust piping is 2.25".

 

[Safe Zone Msp]

My guess is the turbo isn't spooling up quickly enough, hell mine doesn't hit its whopping 5-6 lbs of pressure until about 4500 rpms, but I'm not sure, you'll just have to trouble shoot the ic piping, and vacuum lines, or do a pressure test.

Thad.

 

[Turbojuice]

For the record, stock MSP exhaust piping is 2.25".

Whoops sorry that is what I meant lol.

 

[Turbojuice]

My guess is the turbo isn't spooling up quickly enough, hell mine doesn't hit its whopping 5-6 lbs of pressure until about 4500 rpms, but I'm not sure, you'll just have to trouble shoot the ic piping, and vacuum lines, or do a pressure test.

Thad.

I can get all the way to 6k under WOT and still be at 4 lbs... I will probably try to get a pressure test done and check everywhere for leaks... bummer.

 

[hornsfan10609]

Unbolt the exhuast at the j-pipe before the cats and see if there is a difference. Usually the exhaust doesn't have that much of an effect on boost. I wouldn't put a smaller exhaust on though, that can only hurt performance. Check your WGA to see if it leaks by blowing into the vac line that runs to it. Also check your stock plastic pipes if you still have them, the joint where the BPV mounts can crack and leak.

 

[Turbojuice]

Unbolt the exhuast at the j-pipe before the cats and see if there is a difference. Usually the exhaust doesn't have that much of an effect on boost. I wouldn't put a smaller exhaust on though, that can only hurt performance. Check your WGA to see if it leaks by blowing into the vac line that runs to it. Also check your stock plastic pipes if you still have them, the joint where the BPV mounts can crack and leak.

I am getting a weird turkey noise coming from under my hood at idle when the car is cold. I can't figure out if it is belts or something else. But whenever it happens the car shudders a little... I am wondering if it is the BPV leaking air? I am going to try the vac these tricks as soon as I get my car back from my parent's house.

Unfortunately I am gonna go with the stock exhaust for a while just to keep things quiet. I am keeping the perrin for racing and fun though. Can the Perrin system hook up like a catback? Or the Perrin midpipe hook up to the stock system? Hmm might be an experiment worth trying.