Lunaismaiwaifu

Hey folks, just bought my first Evo last month after almost 10 years of drooling over your rides. Super happy with the car, she has around 35k miles and in good shape.

Since Tuesday I've been having performance problems and pulling my hair out trying to figure out why. I haven't really done much with cars before but I have a coworker who's a really good mechanic and he's been coaching me through the issue, so bear with me.

The issue:

Most noticeably in 1st and 2nd gears, the Turbo doesn't seem to be affecting the car. She'll rev to 5k easily but I don't feel the turbo at all; instead, there's a "woosh" sound coming from the driver's side of the engine bay. Can't hear the BOV valve go off either.

What I've tried so far:

- Inspected all of the hoses I could get my hands into from above the engine bay. Took out the Intake and BOV and checked all of the lines around the area.

- Took the heat shield off with help from a guide in the forums, then moved the wastegate actuator arm to make sure it was functional and not stuck open for some reason. The arm moves with some effort - but it moves as one would expect. One of the main things we suspected was an open wastegate, but I guess moving the arm would reset it?

- Ordered and replaced the more critical stock black relays (probably unrelated to this but I was going to do it anyway) with the ones from SSP.

- Checked my headlight fluid, turbo fluid, tightened my gas cap (suggestions courtesy of 4chan). All good

I don't have a leak tester handy but might invest in one. I guess I don't have many options left without jacking up the car and looking at every nook and cranny, right?

Oh, and to note, right before I started seeing this issue I heard a rubbery "pop" while turning my steering wheel. I'm guessing there aren't many vacuum lines close to the steering column; could be unrelated, but figured I'd give all the info I have.

Any ideas? Thanks for any help in advance.


Edit: I'm taking her in to Mitsu on Tuesday, first thing in the morning either way. But figured I'd try to get my hands dirty and solve it myself if possible.


Edit2: For posterity, the issue isn't a boost leak or anything related to the turbo at all - it's the TC-SST transmission that took a dump. Hooray for warranties, though; still have 5 months left on mine, so that'll be covered.

KVandy15

I'm going to guess that the vacuum line from the turbo's compressor outlet to the boost controller popped off.

Follow the big intercooler pipe that goes across the top of the engine to the rear of the engine where it meets the turbo, that last black metal piece with the flange that meets the turbo should have a 1/8" vacuum line attached, that line runs about a foot and a half toward the drivers wheel to a boost controller located basically behind the positive terminal on the drivers side. I suspect a problem with that line, let me know when I'm wrong.

Lunaismaiwaifu

Hey, thanks for the info! It's midnight but I popped it open again to check just in case, but all of the lines to and from the boost controller seem to be in good shape unless there's a rupture somewhere I can't see.
From what I can tell, one line's coming in from the turbo housing (with a red ring at the bottom, yeah?) and another from behind the intake pipe, and then they split into two (like this) and end at the boost controller. All feel pretty solid in there.

venom225

https://www.evolutionm.net/forums/ev...er-5-02-a.html

build you a boost leak tester, get a spray bottle and put a few drops of dawn in the water. once you have your intake system pressured up spray this on every connection and every hose associated with the intake system. anywhere you see bubbles you have leaky. make sure to catch your bpv to. I like this method best because it will reveal ever small leakers from failing hoses and vacuum lines. you may not have ahose that popped off but you might find several small leakers and that makes a difference added up

Sligo

As advised above, by venom225, 1st step is to do a BLT. Also, consider purchasing the factory boost/vacuum hose assembly as the previous owner may have altered it by perhaps eliminating the inline, brass restrictor orifices, etc.

Lunaismaiwaifu

Hey guys - thanks for the help!

Turns out that occam's razor wasn't right in this case, it wasn't a simple boost leak. My SST had some issues; initially the Valve body was replaced, but I kept having problems for a couple of months. After fighting it out with Mitsu, they finally decided to do a full diagnostic and figured out the clutches were still slipping despite the new assembly. I have a new clutch basket going in as soon as it arrives, so hopefully that'll take care of the issue.