eles1

In a carbureted (or mechanically fuel-injected) engine this would be true, but the MAF should detect the extra air coming into the system and adjust the fuel delivery to achieve the mapped A/F ratio.

 

DKB

Actually, you can also control your A/F ratio on a carbureted engine, you just have to re-jet the carburetor.

It is true that you can't do it electronically like you can in an EFI equipped car. You'll also get more fluctuation in your A/F ratio since the system can't monitor and make real-time adjustments.

increasing the boost DOES change the A/F ratio. more boost = more air = more lean.

 

dR

Ummmm. I think you're confused. Typically when increasing boost, tuners will alter the fuel tables to add more fuel to specifically avoid a lean condition. A/F ratio and boost target tables can be controlled and manipulated independently from each other.

If you were silly enough to increase boost without also increasing fuel delivery, the engine would, in fact, run lean... At least for a few minutes before your pistons burn.

Back on topic:

Sounds like we've had a couple of semi-success stories with this "fix". Anyone else had any luck with it??

Here is my experience FWIW

 

Monday July 25th I scheduled dealer appt for studdering issue

 

Facts:

Car has studdered and hesitated since new

Build date 06/04 Legacy GT MT wagon.

18230 studdering miles

ECU sent out for reflash - 3 days turnaround - despite being told initially it would be 8 days.

 

Findings

Has definately improved situation, nowhere near as bad as before, but still present. Especially in 3rd and 5th gear medium acceleration from 2500rpm.

 

I'm not sure i could recommend it as a completely worthwhile fix - but if its available, my motto is to take it.

How many miles have you put on since the "fix". Simply resetting the ECU seems to make it better for a little while on mine but then it comes back. Please let us know if it gets worse again as you put more miles on.

Well, it's the second day of cooler (70's) air here in Michigan and the bucking has vanished. We had a long stretch (3 weeks) of 90 degree very humid weather and it bucked the whole time. Drove it a bit yesterday and it was VERY mild. Drove her to work today and could not get her to buck at all. Oh and must mention how much faster she feels in this cool dry air. Love this weather...

+1

I've said all along that mine didn't start surging until summer rolled around. Hot weather makes it bad, hot weather + AC on makes it worse.

It's barely noticeable in sub 80° temps.

That's what I'm saying. the tuners are able to lean the a/f out substantially enough to get to a 50hp gain. it's probably not coincidence that after you're reflashed and 50hp to the good, you also no longer have the studder.

 

dR

The increased power comes from increasing the boost, not changing the A/F ratio. Also, I have Cobb stage 1/91 and, while the stutter is improved, it's not gone completely.

ULEV, is exactly the problem. This is why the issue doesn't exist on the WRX & the STI. The STI is tier1, & the WRX is LEV. Both don not have the pre-catylitic coverter in the up-pipe as in our cars, unless you remove it like I did.

WRX's do have a cat in the uppipe, at least throught the 2005 model year. STi's do not.

else1,

 

We should get together some time - maybe in the coming month?

 

I honestly do not think that Winky studders much, if at all - but then again, the local roads here are so crappy that I really have not had a PERFECT test session, either.

 

-A

Anytime. Just PM me a few days ahead and we'll get together and compare notes.

...but only if you promise to spell my username correctly next time...

Didn't Vishnu Tuning resolve this stuttering issue months ago? As I recall, they changed the calibration on the throttle-by-wire and on closed/open loop switch over parameters, resulting in elimination of stutter.

I've also read that Vishnu claimed to have been successful at eliminating the stutter completly, but I haven't heard of any first person testimonials (from LGT.com or otherwise), so I never investigated further. Cobb's stage 1 tuning makes it significantly better. I'm sure a talented tuner could get rid of it completely if that was their main focus..

I'm calling this...

 

A. Wtf??? Find me anyone who says the stutter increases after a ECU reset. Better yet, make a video of you doing this and then subsequently demonstrating stutter for proof.

 

B. Top tier fuels are not necessary, the car is sold in the NA market to run on 91 octane, it must be designed with enough tolerance for the available gas. Yes, "tolerance" this is called "engineering". Nevermind the gas issue is bullshit, actually I'd believe the car should run smoother if you put 87 in, as the ECU is in full panic mode and pulling back timing to it's lowest levels. Not to mention even with the 91 requirement many of us are running 93/94 octane.

 

C. First of all, you would be surprised as to what level some people on this board "understand" their cars, and to what level subaru affiliated people do not. Only the people who've monkeyed with their cars, to say, a stage 2 monkey, seem to have livable results. I'm not even talking about these people though.

 

The ECU is not a magic box, because if it was, it might actually work properly. This is an algorithm problem. It probably really needs to be taken up with Denso.

+1

So... I just got my car back from this "fix" ... and I definitely confirm what was said earlier by Dinglehoser....

 

The problem is definitely NOT FIXED. I would go so far as to say that if it is ANY BETTER AT ALL, it is VERY MINOR... the stuttering/shuddering/surging (note the lack of the not-real-word "studdering") is just as bad as before the "fix." Lame.

 

Honestly.. I wouldn't have wasted my time having this done if I had known it would be this ridiculous. Count another member going the Cobb route to fix this...

 

Unless the ECU learns to not be stupid over the next couple hundred miles or so and this goes away (I'm betting it wont), my recommendation is this: Don't waste time having this done and missing your baby. I regret it.

 

SOA!!!!! :mad::mad::mad::mad: FIX THE PROBLEM FOR REAL!!!! DONT WASTE MY TIME! The Legacy 2.5i doesn't do it... at all. Period... why does the top of the line GT do it? FIX IT!!!

That's exactly what I was afraid of... Thanks for the info.

I'm sorry but I've read this thread up to page 13 and have been wondering what this studdering problem is. Does it occur when you are starting to move the car. I know for my car if I try to go too low it starts to shake a little and that has a huge surge of power pulling me above the 1.5k RPM mark even though I was only trying for 1k, even though I am no longer on the clutch or gas.

search

Just got off the phone with Cobb. Current maps WILL work with the new flash revision, and Cobb is aware of the stuttering issue. It seems that it's an iterative process by which they're methodically tuning out the stutter/hesitation. The rep I got on the phone seemed to think that it was a combination of A/F ratio inconsistency across the band and crappy stock throttle-by-wire tuning.

 

I'm gonna march up to SMART here in Seattle and pick up an AP, post haste. I've had it with this SOA bullshit.

If Cobb came out with a map that focused on getting rid of the stutter, I would be very interested in that. Even if it didn't put out as much power as their current stage 1 map, I think I'd go with it anyhow. As long as it was putting out at least factory power.

I just got my car back from the dealer today. What you guys have been waiting for ... THE RESULTS OF THE FIX:

 

... it doesn't actually fix it completely. It does alleviate the problem somewhat, but give it about 1/2 throttle in 5th and you'll still feel those familiar pulsations from 2k to 3.5k or so, every time. The magnitude of those pulsations, however, seems to have decreased somewhat. Overall, the problem went from extremely annoying to very annoying. I'll let the ECU relearn for a while longer and report back.

 

An interesting side-effect is that the idle seems to have gotten rougher.

 

Not only does the problem still exist, but the monkeys there left water spots all over my freshly waxed car. Guess who gets to acid-treat and rewax ... AGAIN ...?

Thanks for the update.. I hate to sound pessimistic, but it will probably only get worse as the ECU re-learns. My stuttering is always better immediately following an ECU reset, but it always comes back within a couple hundred miles.

On the bright side, I think your rough idle should go away as the ECU re-learns. That seems to be a side effect of an ECU reset that goes away over time.

Hmmm, If this is actually a logic change I wonder how the current reflashes will jive with different logic? Has anyone with a Cobb reflash tried getting this dealer reflash or is everyone happy enough with the Cobb map that they aren't going to bother?

I have an AP, and I plan on trying the dealer fix. The AP makes the stuttering a little better, but still doesn't get rid of it to my satisfaction. I'll be "divorcing" the AP before my car goes for any service. I'll decide if I want to reinstall the stage 1 programming afterwards.

the only prob with the old ones is that they smell kinda funny from years of use. But otherwise, they run great.

Just saw this thread and thought I'd re-post what I put in the non-sticky thread....

 

Quote:

Originally Posted by me

I spoke to my Subaru District Service Operations Manager in mid-June. He test drove the car, and confirmed that this is "surging" and that it is the same phenomena that can be found on all 05 LGT 5M's. He initially said that there was nothing that he could do because it was "normal" meaning that the car was running as it was designed, albeit shitty. The issue is that the car is running lean at that point to meet emissions standards. He said that the '06 models would have the same engine hardware, but a different ECU map which gives more horsepower, but he couldn't be sure when that ECU map would be available, or if they would be able to use it on an '05. While I was in the process of telling my dealer that they could take the car back, I got a call from the Ops Mgr who said that Subaru would have a fix at the end of June. Since I really want to keep the car, I decided to see what would happen. He didn't call like he said he would, but I called early this month and learned that the ECU flash was available. I took the car in last week to have the work done, but the problem is not fixed!!!! They did change something in the map, because the stuttering/surging isn't as bad, but it's not fixed. I took the service writer for a test drive, and he said it was turbo lag. I won't go there. So the next step is to let the tuner at my local dealer take it for a spin with his PC attached and see what he can tell me.

 

This is complete BS. I can't believe that Subaru is treating customers like this! I'm a young guy who's spend a lot of money on a car, and will be buying many more cars before I take the eternal celestial dirt nap. They claim that they're trying to build their customer base back, but this isn't helping.

 

[/size][/font]

BigBen,

Did they pull your ECU and send it out, or just perform a reflash while still in the car? Just curious to see if the solution they gave you (which apparently didn't work) was the same as the one Opie bought to our attention with this thread.

Has anyone had success with this new "fix" yet???

I'm just interested to see if any dealership will actually fix this. So far none of the ones I have talked to know what I'm talking about. They are treating me as if this is the first time they have ever heard of the problem and there is no fix. Why aren't the dealerships aware of this? Did they not get the same email that Opie got?

I got the same thing from my dealer when I mentioned it but that was before I got the info from this thread. Now that I know that SOA is aware, I'll be taking it back as soon as I can to try again.

took mine into the dealer today. They couldn't duplicate it, so i drove them around in mine and showed them. Then told them to pick any 2005 2.5 turbo off the lot, 5EAT or 5MT and I'll duplicate it on that too. So they did. And I did. And now they're looking into finding that TSB. They called the SOA tech line, but the tech line hasn't called them back yet.

Good info. I'm interested to see if anyone actually has success with this new "fix". Keep us posted...

Duplicate it for them.

It's much more noticeable when driving as opposed to riding along. Also, I didn't notice it myself throughout the first few weeks of ownership.

It's subtle, but annoying...