Mitsubishi Lancer Evolution Forum banner

No boost past 20PSI

2069 Views 7 Replies 7 Participants Last post by  linkbeat
After some intense driving in a track day, my car stopped boosting over 20PSI and I could hear air escaping from somewhere. I checked all hoses and nothing looks loose. tried to do a boost leak test but couldnt find out any leaks. What else can I do?

The car seems normal from idle to around 20PSI. At idle the boost is -20 and AFR is at normal levels.
At WOT, after 20PSI the AFR becomes 10 with a loud noise of air escaping coming out.
1 - 8 of 8 Posts
Could the boost controller be the issue? I know a faulty one will leak like crazy under pressure. You did a leak test past 20psi?
Definitely a boost leak. Just do a proper boost leak test with 20+ psi.

Just my noob 2 cents, but if it actually doesn't start until a certian psi you might want to check the bov. It could be failing and starting to leak. Complete speculation though, someone more knowledgable will probably chime in shortly.
or a loose coupling. Like they said, do the leak test and find out where you are leaking from.
how much psi are you tuned or supposed to hit at full boost?
Suppose to hit around 25 PSI. But i can clearly hear air escaping after around 20 :s
Is the "air noise" a high pitched sound?
Is the "air noise" a high pitched sound?
This is funny. I have the same problem. I just installed an EBCS and got road tuned last Saturday and ever since I have the same problem, and I would guess it's also around ~20-22psi.

The "air noise" is definitely a high pitched sound. I tightened the hose clamps to and from the EBCS, but I suppose it could be a leak in one of the fittings. I tried tightening down the fittings on the EBCS but they're already as tight as I can get them.

Chet suggested it may be the stock BPV. Any ideas?
1 - 8 of 8 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.