acceleration hesitation

[jp928]

Has anybody with this issue in a turbo tried the 'fix' used on non-turbo Subys?
It has occurred for a long time in the NA engines, and one fix is to attenuate the knock sensor signal, either electrically, or by putting a rubber washer between the sensor and the block - I can attest to this working on my 2.5 Outback. A guy in the states makes an electrical fix that goes in line with the sensor connection.

jp

[Roddez]

I have found that I can alleviate this issue by changing my driving style.

I notice this hesitation in 2nd gear. If I am on a trailing throttle in 2nd, I just add a small amout of throttle until the engine comes on boost, and then gently put my foot down. This results in a smooth surge of acceleration.

[jp928]

Thats fine when you CAN safely add some throttle (BTW, how do you know when its got boost - gauge, or seat of the pants?) but in traffic there will be many times when you cant safely keep it on boost. Is there a re-learn ignition procedure for the turbo cars like the NA ones ( 5 runs in 3rd gear from 40-65kph WOT) ?
jp

[blacknwhite]

Noticed for a while this stutter on my car, had it in for service today ,told them about it . Anyway they took for a test drive and the guy agreed he found the same issue and had seen with other MY07gts and they were sending a report to Subaru and wil get back to me in a few days. OK I thought, get a phone call 2 hrs later from service manager almost apologetic for what he is to tell me " are you using 98 ron"
"yes"
"ah what brand"
"BP ultimate, get it from a large servo so I know its turned over often"
"Subaru wants you to try Caltex"
"but this has been since new"
"yes I know and its a pain but Subaru wants to try Caltex"
I honestly believe the guy knows that this is crap but has to tell me anyway,as he drove it and got the same result
So Subaru tells me the car they sold me supposedly capable to run on standard unleaded now needs to run on certain brands only on 98
I did not mention that I read the U.S forum that is now at 25 pages on the reflash for this stutter as I dont know about thier emissions and specs differ from Oz.
So Ill try Caltex and then ring them back

Not a happy camper
Oh and by the way 12.5k service $257 , would not have minded if the stutter was fixed but it wasnt and treated like the village idiot to boot
Pete

[JimmyGT]

What a load of garbage. I have a MY07GT-B and have put nothing but Caltex 98RON in it, and used to experience this stutter.

I have since had an ecutek tune done and stutter is gone.

[jp928]

Does the book specify 98? I thought it was 95....
jp

[jp928]

Jimmy, tell me whats involved in the ecutek tune, cost, and effect on warranty please?
thanks,
jp

[tangcla]

The book specifies 98RON for the MY04 GT, not sure about the MY07.

I believe the stutter is caused by the drive-by-wire electronic throttle gadgetry being overly sensitive, thus closing the throttle for you. A tune will help this, and the Sprintbooster will be a bandaid solution to some degree.

[Roddez]

(BTW, how do you know when its got boost - gauge, or seat of the pants?)

Seat of the pants. You can feel and hear when the turbo starts to build boost. You can also feel when the boost stabilises, and it is at that point that I slowly press the pedal further. If I slam it down, it will hesitate, surge and accelerate, but not smoothly.

One of the most reasonable explanations is that the emissions system decides that the car is producing too many emissions and backs something off. Then it's okay, so it opens up again, only to decided that it is bad . . . and on the process goes.

Subaru have reset my car twice now and there has been no change in this issue. But what I do know is that this is a very complex engine and as such, this issue is also quite complex.

[tangcla]

One of the most reasonable explanations is that the emissions system decides that the car is producing too many emissions and backs something off. Then it's okay, so it opens up again, only to decided that it is bad . . . and on the process goes.

From what I heard from my tuner it's not the emissions, it's the knock sensor. So it detects knock and closes your throttle for you.

Have you tried using higher RON fuel, or an octane booster?

[jp928]

Roddez, if its the knock sensor as indicated by Tangcla above, why not try the mod I mentioned - unbolt the knock sensor, fit a rubber washer under it, bolt it back up. Needs to be a fairly hard bit of rubber to allow you to tighten the bolt up enough not to work loose- only need 1-2mm . Its just left of centre on top of the crankcase, with a single wire going into it.
When my OB played up on me, despite running 98octane always, the rubber washer transformed the response.
jp

[tangcla]

I'm curious to know how this hesitation feels like, is there anyone in Melbourne who can demonstrate? I mean, I might have a similar issue in my GT, just that I've never noticed it

[JimmyGT]

tell me whats involved in the ecutek tune, cost, and effect on warranty please?

The tune basically took a morning.
Cost = expensive @ $2000 (MRT claim most of this is the Ecutek software licence fee)

Warranty = MRT claim that if there is an issue they can flash ECU back to factory and Subaru would never know. They also claim never to have had an issue with a car as a result of a tune.

Results = It is a completely different car with much, much more get up and go. From memory dyno results show + 30kw +25% torque (don't quote me on the results it has been a long time since a looked at them)

I mean, I might have a similar issue in my GT, just that I've never noticed it

If you had it you would know, as it is very noticible.

[coyote]

Warranty = MRT claim that if there is an issue they can flash ECU back to factory and Subaru would never know. They do claim never to have had an issue with a car as a result of a tune.

Ecutek is a good product and they have some competent tuners, but both those claims are .. well .. lies.

[tangcla]

From what i know the ECUTek can't be reflashed back to OEM. but OpenECU can.