Doing a 3rd gear WOT pull I hit 5K rpm, full boost at 25psi, AFR was reading 10-10.5 on 91 octane. Lost boost instantly and went into vacuum at 22-24 InHg, RPMs held at 5K. Let off the gas and shifted into 4th, after I changed my shorts I checked to see if it would hold boost pressure again which it did through all of the gears. Now I usually never go above 5K in 3rd so I've never experienced this before and when I do my pulls it's usually in 4th. I checked the plug gap and they checked about .024" and cylinder 1 was about .026" so I closed it up to match the others, other than that the plugs looked great. Checked all my vacuum hoses and clamps on all of the piping and everything checked out but I did tighten the clamp connecting my intake to the turbo a bit. Now I do have a rev hang issue that starts at 4k but only when I'm at full boost, the revs will jump 800-1000 when I clutch in. It's been a couple years since it was last tuned so I'm due for a new tune but I think these need to get worked out before I come in so my car doesn't blow up on the dyno. Attached is a video I found while researching this problem.


So far it seems like the general consensus is a bad BOV, I'm currently in the market for a stock metal Evo IX BOV. What do you guys think? I will be running a compression test and boost leak test this weekend, I will post results when completed. Any help is appreciated! Thank you.

 

That AFR is waaaaay too rich... Do you have a MBC or EBC? And a bad BOV would make sense.

 

check the wastegate. looks like its being blown open.

 

Yeah I was thinking it was super rich. I should probably shoot for around 11-11.5?

Sounds good, I'll double check everything. Anything in particular I'm looking for?

 

I could be wrong, but it sounds like it doesn't bypass/blowoff until you let off the throttle. It almost seems like once your gauge peaks/beeps, it drops off on the gauge, but by the sounds of it, the car still holds boost until you let off. I could be hearing things.

 

A malfunctioning wastegate shouldn't cause absolute loss of boost... He should still be able to hold SOME boost atleast with a malfunctioning wastegate...

How are you controlling boost?

 

Sorry I missed that question the last time! I have a Forge MBC

 

Compression test results are 155-155-162-162. Waiting for the JB Weld to cure and then I'll do a boost leak test. Checking BOV and Wastegate now.. Wastegate looked alright. I think the BOV is the issue. I ordered a IX MR OEM metal one, should be here in a week or so! Also, no leaks found during the test.

 

Finally got my Openport 1.3U in the mail today.. Figured out why I'm running so rich. See attachments.