I know that this issue has been brought up before, however, none of the threads seemed to ever answer the hesitation question I have.

My '02 WRX:

Vishnu Stage 0 (ECUTEK, underdrive pulleys, uppipe)
Boost Gage

The Problem:

Under medium to hard throttle there is noticable hesitation from 2500rpm to about 4800rpm (give or take). It does not seem to be related to boost - my boost comes up smooth to 1.1 to 1.2 bar. Gear selection has no effect, but the hesitation is most noticable in 3rd through 5th.

Attempted Fixes:

I only use 92 octane from Shell or 76. I have replaced the stock plugs to try and fix the issue, but with no luck. I am now running 1 range colder NGK Iridium plugs. Still have same problem. Can't here knocking or pinging. Regaped the plugs to .026". Reset ECU. Most noticable going up hill.

I would appreciate any help possible. I am going to try the dealership, but they usually know less than me, and I am not that smart!

Please help!!

 

This may not be entirely helpful, but here's an interesting critique of the underdrive pulley and its effect on the EJ20T:

http://www.spdusa.com/pulley_kit.htm

This guy loves raining on the parades of the other tuners, but he seems to have the science and experience to back it up.

 

i doubt it is the underdrive pulley unless it is installed incorrectly. But that should be pretty damn obvious if it was the case.

CA gas?

And stick with 76 only no mtbe makes for a cleaner burn (at least in my car it sure as hell did).

 

His pages are interesting reading but he is in error if he maintains that the main pulley on a subie is a "harmonic balancer". It is not a harmonic balancer. It is a weighted pulley that acts like a miniature flywheel at the front of the crankshaft snout. A harmonic balancer uses a different construction or mechanism to smooth out torsional vibration, something a pulley does not do.

Some facts about torsional vibration and how to dampen them (I typed the above paragraph before reading Fluidampr's page).

I used to cringe in horror while watching my old V8 buddies using a heavy mallet to drive home a harmonic balancer (damper or dampener), instead of using the recommended installation tool which draws the damper onto the crank snout. That's one way to destroy the elastomer bonding between the outer ring and the inner hub on a Chevy damper.

--
0==WW==0
"…axles of evil…" - george w. bush

 

Interesting thoughts. I will stick to 76, as I have heard the same advice twice now.


However, does anyone have any direction to point me on the hesitation issue?

 

I did the grounding mod and my hesitation lessened....

 

I've heard the same thing - that the grounding mod helped out. However, I would like to complete get rid of the issue. There must be some source to the issue?

Any other ideas!?

 

Lets just put it this way....take what you can get and be happy it isn't worse than it is.

There is no macic bullet.

 

It sounds similar to my on-going issue with the power pulsing I have in 3rd-5th over 3k RPMs at WOT. I tried the grounding mod, which did very little. (It did help out with the light brightness, stereo performance, and starter response, however...) I took a Subaru tech for a spin, and he did some digging and came up with a cracked coil. Replacement did very little. A talk with Vishnu seemed to point towards a boost issue of some sort...They said they've seen failure in stock turbos at as little as 45K miles, and it could also be a leaky BOV or stuck wastegate actuator.

That's as far as I have goten. I'm headed back to the Subaru garage to have them rip the turbo guts out to examine. Hopefully, that will do the trick.

If it doesn't, I'm off to trade my '02 for an STI. =)

 

If you still have the old Pulley lying around, try re-installing it and see if, perhaps, that is the case. I have the Vishnu pulley on my car with no hesitation issues, but I have a different setup (Equivalent to the Vishnu Stage 1) on my Wagon. It could save you a turbo rebuild/dealership fiasco, and if it doesn't fix it, at least you will have eliminated possible problem.

To me, tearing apart a turbo seems to be one of the LAST things I would do. Generally when trouble shooting I try to check the easiest solutions before I go through with the serious stuff. Just my opinion, though.
-Etch

 

I completely agree.

...unfortunately, I *have* tried everything else, so I think I'm personally down to tearing the turbo apart. =P

I'd agree on the pulley, from what I've seen so far. It's a good palce to start.

 

Hmmm. More options. I do not see how the pulley would have any effect on the hesitation, but I could change it to see. I have also talked to Vishnu many times about this issue and I have even sent my ECU back to them to reprogram it just in case - again, with no change in the issue. I am set to purchase the Stage 1, but I cant bring myself to do it until I find the hesitation issue.

Lets keep trying. Anyone else!? I sure seems like I am not the only one with unfortunate issue.

Any stock WRX owners with this problem?

 

Part of the problem is that even though I have read your description of the problem several times, it isn't the same as sitting in your car and seeing/hearing it for myself.

I have a reflash and in the higher gears, if I am cruising along and nail the throttle at 2500 RPM, the acceleration isn't anything to write home about until the R's climb to over 3500 RPM. Also, the car seems to accelerate more quickly if I ease into the throttle gradually from a lower RPM, rather than W.O.T. immediately. I haven't conducted any tests so it may be a subjective thing...

--
0==WW==0
"…axles of evil…" - george w. bush

 

Mine *is* stock. I've been attacking this probelm since the day I bought the car, which led me to the grounding mod to start. When I talked to Vishnu, they told me not to even think about an ECU reflash until this problem was addressed, because that could just further the problem.

How many miles do you have on the car? When did it start happening? Have you tried going back to stock plugs?

 

DJ Catchem -

I have just under 37k on my car. Bought it used with 23k on it. No issues to speak of then. Put the Stage 0 on with about 27K, no problems until about 32K.

I have tried the stock plugs again with no change.

Wingless wonder -

I agree that power builds slow, but I know my car with and without these issues. And I know something is not right.

I wonder if any you have experienced a seemingly greater accelerating when hesitating if you simply back off the throttle a very little bit? If mine is beginning to stumble, I back off and I actually feel a bit more power. Very strange. Makes me think its ignition related.