Hey all,

This is my first post, but I've been lurking for a while. I bought my '05 Evo MR in mid-August (used). When I bought it, I was for some reason under the impression that Evos made 17 psi of boost, so seeing 1.1 kg/cm^2 on the boost gauge didn't set off any alarm bells. Seemed a little low but fine. It was dumb of me to not do the full research, but that's in the past.

Anyway, I read that '05's are supposed to make 20.3 psi peak at 3500 rpm, which should read as about 1.43 kg/cm^2 on the gauge. I realized that I had a boost leak. I got a boost leak tester and pressurized my intake with my little air compressor that runs off my cigarette lighter. Couldn't pressurize my intake past about 0.5-0.6 (7.5-8.5 psi). I heard air leaking somewhere around the intake manifold area, and it changed its tone when I worked the throttle, so I did the throttle body shaft seal replacement detailed in the how-to section. I had a hard time with it and may have messed it up. I had an extremely difficult time removing the old seals, and may have nicked something; I also had a hard time getting one of the new seals in. I put the new ones in with the open end facing inward, like the write-up says. It didn't seem to help (or hurt); I still peak at around 1.1 kg/cm^2 and hold there.

I tried taking the car to the dealer. I went to Elkins Mitsubishi in Durham, NC and they told me that Evos are supposed to boost between 7.7 and 11.6 psi. I told them they were nuts and they showed me their service manual. I double-checked a service manual on the Internet, and it does say that. I know it's wrong but I can't blame that dealer too much for obeying their manual.

I called Leith Mitsubishi in Raleigh, NC (not their Cary, NC location, which is on the blacklist here in the forums), and asked them what peak boost is on an Evo. They gave me the correct "20.3 at 3500, 17.4 at 6500" figure, so I took them the car. They said my boost gauge was bad and replaced it under warranty. The new boost gauge reads exactly the same as the old one, so now they're telling me "20.3 psi is the maximum, and not all cars make that." I said "Well how low would it have to be for you to do something about it?" and they said they didn't know but would find out.

I'm looking for advice. Trying to track the leak down myself was pretty frustrating, and so I'd really like advice on how to get help from the dealer. If that's not going to work, I could use suggestions as to where to take the car (I live in Raleigh, NC). Barring that, anyone have good ideas on how to fix the leak myself? I tried soapy water but couldn't find where it was coming from, and I tried replacing the throttle shaft seals but it didn't help. As I said, I may have messed it up, but I don't see myself having greater success if I try to redo it. I've heard Works rebuilds throttle bodies but it's a lot of money and I don't want to go down that path if I'm not positive it'll fix my problem.

 

hey man, where in NC are you ? you can come down to fayetteville and we can help you the best we can.... we found a leak on my friends evo behind the throttle body on a vaccuum hose back there... you cant see it unless you are laying under the car and looking exactly where it is.... you can feel the hose i am talking about if you reach your hand behind the intake manifold near the fire wall and feel around for hoses... we and up fixing his car and it holds 27 lbs no problem, before that, we couldnt even build any pressure when leak testing. also, your pump probably will not pressurize the system enough to hit anything about 15 lbs... i have a 3 gallon tank and i can push it past 20 or so... it starts to be too much pressure for the tank to push in...

 

Hehehe...Ric beat me to it but I'm the guy he's talking about. We'd be more than happy to help you track this leak down.

If you aren't busy tomorrow night you should head down here for the Freaky Friday races at the drag strip. You don't have to race if you don't want but it usually a good time either way. We usually meet up at one of our houses, do whatever maintenance is required and then head off to the track. PM either myself or Bigric09 if you're interested.

 

"USED"

Iam thinking that the 1st owner could have had a MBC on there and not put it back to stock corectly .

2x check the stock BCS , hoses and for the pill and see if thats all in like its spose to be .

BTW the air comp you had may have been too small for this job and/or the motor may have not been @TDC (all valves closed) also i find it helps out if the motor is warmed up when doing a leak test

 

very good point matt, that is probably exactly what it is....

 

there are two vacum lines that are back behind the throttle body one points down wards the other to the side towards the passenger run your hand down the back of the intake manifold and you will feel what is almost like a coin and bellow that will be the vacum line and a little up and to the left should be the other one. . . i would check those as the guys before stated that is where the leak is most of the time

 

Thanks for the help. I can't make it down to Fayetteville tomorrow, but I've been wanting to meet some other Evo guys and I've never been down to the strip so I'd like to meet up sometime. Is Freaky Friday monthly?

I'm going to look this weekend for these vacuum hoses. They're not on the throttle body, but behind it someplace? Do they attach to the intake manifold? How much boost were you making with the hose leaking? Was it a leak or was the hose totally off? Would generic vacuum line from Autozone be fine to replace a leaking hose?

I'll also check for the vacuum line restrictor pills. I read this thread and this thread . Apparently there are two restrictors, and removing the one in the vacuum line near the turbo will make it so that the car won't boost over 11-12 psi? My car boosts 15-16, so it doesn't seem like I'd be missing that one. Removing the one near the BCS apparently increases boost by 1-2 psi, though?

If I have no luck this weekend, I'll PM you guys.

 

I think these guys are talking about the EGR vacuum lines. They shouldn't cause your boost to be that low. I think the answer lies in the BCS or the hose for it. but anyway, here is a picture of the vacuum hose I believe they are telling you to check.. this is from the 2005 Service Manual

 

If you end up doing another leak test yourself get a bottle and fill it up with soapy water... spray it all over all the ic/vac line connections. This will help you find a leak (you should see bubbles) if indeed a leak is your problem.

 

Also, are you still hearing a leak at the throttle body shaft seals after doing the seal replacement? i.e. it changes pitch when manipulating the butterfly valve?

 

To be totally honest, after I did the throttle body shaft seal replacement, put everything back together, took it for a test drive, and saw the same boost as before, I got totally frustrated and just went to bed without doing another leak test (I was doing it on a weeknight after work and it was near midnight by the time I was done).

I took the car to the dealer a couple of days later figuring I could just let them sort it out. Didn't realize they'd be so unwilling to help. I'm pretty sure they don't do boost leak tests like we do, and the guy Elkins Mitsu in Durham looked at me like I was nuts when I described the process so I didn't mention it at Leith. I think when Leith got my car they assumed the boost gauge must be bad right off the bat and replaced it, but I don't think they did any other troubleshooting at all.

I'll do another leak test Saturday, along with checking for loose vacuum lines and poking around the boost control solenoid.

 

Most ppl who work at dealers know 1/10th of what they should to be working on our cars (I had to learn that the hard way again and again )

I really dont think a boost leak is your problem , it would be a rather LARGE leak to only run 17 psi (The stock plastic bov that came with my 2003 would start leaking @11psi and @15psi its was leaking very bad , BUT i still could run upwards of 23 psi) .

Shoot , Just cut to the chase and get a MBC and be done with it

 

there you go... i will be selling my forge one shortly if you want to wait a week or so and you can even come down and we can install it so it doesnt have to be shipped

 

what im referring to is where the yellow dots are... not sure which dot it is exactly but it is definitely not on that side where you pointed...but that could be another spot

 

man iam sorry to read your problem,first check the lines that control boost on your turbo maybe the previous owner had a MBC and he went back stock and messed up things!
then check for leaks it must be a huge leak to not past 1.1bar!
most probably not a leak!

its incredible that dealerships in the USA dont know **** about cars! man here in my country we have a few evos and we dont take them to the dealer cause they dont no nothing cause they have sold only 2 of them, but in the USA that they sell dozens of them how come they dont know nothing its incredible??????????!!!!!!!!!!!!!

good luck, if not just buy a boost controler and you will be fine!