Chirish

iTrader: (1)

So I picked up an 03 Evo that just turned 4k miles about 3 weeks ago. For quite sometime, the car was incredibly quick and pulled strong all the way to redline. Come last week, I noticed the car didn't have as much power, and the power that it did have didn't seem as smooth. At about 4.5k RPM's, the car feels like its losing power (boost spikes to about 19psi, then drops to about 16psi), then the boost comes back on slightly higher and goes to about 18psi at redline (but still feels slower).

At first, I thought it was knock response since I'm here in California with 91 octane and it was a little warmer the past week or so. However, today I filled up with some 96 octane from Sears Point and its still having the same problem. I've checked for boost leaks, but not thoroughly. Where are the common places for the leaks? I'm thinking of just picking up a full Injen intake with the upper IC piping to see if that solves it.

Anyone have a similar problem? And yes, I've searched for boost leaks, but I'm not positive that this is the problem.

Thanks!

EiEVO

iTrader: (9)

boost leak sounds like your problem.

h.funk

iTrader: (4)

Slipping clutch?

scott yo

iTrader: (14)

did you do an actual boost leak test?

EiEVO

iTrader: (9)

this was stated in the first post.

EiEVO

iTrader: (9)

it has pretty darn low miles but still a possibility. I say adjust your clutch pedal. Because if it is adjusted too high that when it warms up the clutch fluid expands and then it dis-engauges the clutch a little bit to cause it to slip. I have seen this happen on 1 evo and a lot of 1G & 2G dsms..

Warrtalon

iTrader: (6)

He said he checked and searched for leaks but not thoroughly. What that means is he LOOKED at his IC pipes and determined there were no leaks. That does not mean he did a boost leak test. If he had done one, then he wouldn't have said "but not thoroughly." You can't really do a boost leak test without being thorough. I think it's just the common mistake of getting a used Evo, not understanding how it works, and thinking you can check for boost leaks through visual means or by tightening hose clamps.

A boost leak test needs to be performed, but I bet h.funk called it: a slipping clutch. We need him to explain the symptoms in MUCH more detail, but I wouldn't be surprised if that's what it is. I have a hard time believing the boost spikes, then falls, then goes back up again like he says, but I would sure believe if the RPMs were doing that.

h.funk

iTrader: (4)

A Clutch goes out at any speed or temp. Boost is prob the cause but a clutch is very possible.

Warrtalon

iTrader: (6)

Adjust the clutch pedal? EiEvo, that was a strange suggestion. I'm not sure what you think you've seen on other Evos and DSMs, but it certainly wasn't what you tried to explain.

h.funk

iTrader: (4)

An 03 with 4k is prob. track miles. Or drag miles. imop.

dxbevo9

iTrader: (6)

I have a IX...on my defi boost gauge... while pulling hard...with a consistant (non-hesitating) RPM..my boost spikes to 20psi...drops back to 16psi and then spikes to 19 psiand then drops to about ~18 towards redline...is this normal?

thanks guys in advance guys...

Chirish

iTrader: (1)

Thanks for all the fast replies, guys.

I should mention that I'm mechanically inclined enough to know how the Evo works, I've owned turbo cars in the past and am quite familiar with boost leaks, charge piping, etc. I made it a point to mention that I did not check "thoroughly", because I wanted to see if these symptoms were common ground on these cars before I went tearing everything apart.

The 4k miles are not track/drag miles in the slightest bit - the car sat because the previous owner traveled for his job and also has a company car. The clutch feels extremely solid, it just kind of shakes when the car is cold.

On my next day off, I will pull the spark plugs and check them out, and also make the boost leak tester. I was planning to buy upgraded intercooler piping anyways, so I might as well just do that and see if that will cure the problem.

A large part of why I think it might be a boost leak is because when I first got the car and drove it back home, I couldn't help but be at WOT since the car was so damn quick - then taking all my friends for boost-happy rides, so with all that pressure I certainly think its possible to tear a tiny hole or something.

Again, thanks for the replies and I will try and check all that was mentioned, but please keep the opinions coming!

Evo_Jay

iTrader: (17)

If it was during the day, I would put a bet on the ****ty gas. Did you fill-up at a different station or with a different brand?

FYI, I have seen a dyno, done on back to back days with the same car (no changes), showing 76 gas out proforming Chevron gas by a nice margin. Also, Shiv (Vishnu) recommends 76 gas and he tunes a lot of 91oct cars.

If its not the gas, my next idea would be boost leak, like the others say.

That or you just got used to the power, which is very common and why we have mods.

hbruce16

iTrader: (3)

My 03 EVO felt like it was loosing power also so I had the emissions check and system flush done by the dealer and it made a world of difference. I also had the plugs replaced. I have 25k miles on it and it's been sitting in Myrtle Beach since last September when I deployed to Iraq. I'm betting if you have an emmisions service done and change out the plugs it'll be good as new. I know if you dn't drive that much and only do short trips it has a tendency to foul the plugs and load up.

Just my opinion, but the $$$ was worth it for me..it felt like a new car...and I did it at 12k miles.

Evo_Jay

iTrader: (17)

^^
Good idea bout the plugs.