MY08 GTB Auto - Shudder on takeoff

[Std08GTB]

Hello Brainstrust,

This issue has been around for a couple of months now.

Often when I accelerate from a stop, I get a shudder, as in poor running engine. It is completely random, but probably on 10-20% of takeoff's it happens.

I'll be sitting at the lights, then I accelerate and not only does it hesitate but it runs really badly. It happens in I, S and S+ modes. It doesn't clear up with rpm for a few seconds.

On the face of it, one could be mistaken for thinking that the fuel is dodgey.

I took it into Subaru for the 40k service. They noticed the problem when I told them to keep an eye out for it, they reset the engine computer, but it started to play up only 2 days later.

I caught it one morning, drove out of the driveway, then 100 metres to the lights and it ran like a chalf cutter right through the rpm range for around 20-30 seconds.

Subaru said they don't know what's wrong and send an ECU capture to head office with no response.

It has been VTuned but they don't think it's the cause.

There is also a noticeable rough running spot at 1,400 rpm in the rev range.

Has anyone got similar behaviours?

BC

[TorpedoCreative]

hmm... no shudder on take off but now and again a small shudder between 1st and 2nd (generally when Im flat out and using the paddles to change gear)

J

[GTSPECB STI]

Common and known problem associated with dbw throttle I believe. You need a good custom tune to smooth things out imo.

[SillySora]

I had this a couple of times 3 I think. Assumed it was cause my gearbox was under a bit of pressure with 225 atw

[Lukovitch]

Subaru think they can solve everything by resetting the ECU. You really need to get someone who knows what they are doing to put it on a dyno and diagnose the problems... You may be able to push Vin at STI to do it for you...

Mine hesitates, stutters, surges, it seems temperamental but as GTBSTI said, its related to the electronic throttle and the crap factory tune and the only way to get rid of it is a good custom tune (which is going to happen soon ). Subaru's solution to my questions about my car behaving like this was...... reset ECU!!!! lol.

I know my problems are known problems and nothing "wrong" with my car, but yours sounds a bit more serious..... hopefully is just a stuffed sensor...

[cpitts]

<snip>
Often when I accelerate from a stop, I get a shudder, as in poor running engine. It is completely random, but probably on 10-20% of takeoff's it happens.

I'll be sitting at the lights, then I accelerate and not only does it hesitate but it runs really badly. It happens in I, S and S+ modes. It doesn't clear up with rpm for a few seconds.
<snip>
I caught it one morning, drove out of the driveway, then 100 metres to the lights and it ran like a chalf cutter right through the rpm range for around 20-30 seconds.
<snip>

I also get this. I have a manual so it's more of an issue if I'm idling along in traffic and applying VERY light throttle. The car will be smooth as silk then start jerking uncontrollably like you're learning to drive a manual for the first time! Push the foot in on the clutch, let the engine balance and let it out again, and all is fine.

It's clearly a DBW/ECU programming fault. My car goes in on Wed for a service at Docklands STi and I've not doubt they'll just reset the ECU and tell me it's fixed. I know it'll return as I've already done that as part of my own analysis, better keep them WELL informed when I go there, do'nt want them coming back with dumb answers.

[Golf Tango - Bravo]

By reset the ECU you mean take both battery connectors off for 10 seconds? Ha.

Please do us a favour and tell us how you get it fixed..!

GT - B.

[Std08GTB]

Let me know what happens cpitts and I'll take mine straight in there if you get a result. Resetting of the ecu helped for a day or two.

[cpitts]

No fault found (well, there's a surprise!). No error codes and reset the ECU.

Mind you, they invited me back to have a sit down drive with me to demonstrate the fault. So given I have some time, I might do this.

As an aside:
Talking with Vin he acknowledge the massive flat spot when you put the foot down. I said that it looked like it was an AFR issue, which he also acknowledged. I mentioned about the horribly rich AFR (@ WOT) and reflashing it out to get rid of the issue, but he suggested it may be actually running lean at part throttle ( running closed loop AFR monitoring ), but the amount of right foot I'm giving it, I'd doubt that's the case.

The DBW map was mentioned about this stuttering and stalling issue, but the svc mgr (Laurie) thought it was more likely the engine labouring at such low rpms and that I should instead use the clutch and throttle blips to move the car along. He didn't seem to like that I compared it to a WRX DBW system that I'd owned and how it never had those issues.

[Std08GTB]

Im booked in for Tuesday, I said I'm leaving it there until it is fixed. It stalled twice on me this week of which one time nearly resulted in a big smash. Bit frustrating for an auto. I suspect they will find nothing wrong too as it is hard to replicate the issue. Dare I say could a v-tune could cause this???

[cpitts]

Unlikely to be the V-Tune, but depending on what's been fiddled with, it may show it up a little.

The only real fix is an ECU reflash to fix the crap AFR.

[Std08GTB]

Took it in yesterday first thing (and that's early for the Suby guys here), got a call at 10am saying they want to keep it overnight so either they found something or nothing, I shall find out today hopefully.

[cpitts]

Doesn't normally need to take overnight to replicate the issue though. :/ Ah well, see what else pops out of the investigation.

[overl0ad]

random question: have u swapped fuel brands since the tune?

[GTSPECB STI]

Unlikely to be the V-Tune, but depending on what's been fiddled with, it may show it up a little.

The only real fix is an ECU reflash to fix the crap AFR.

Subaru will not be able to fix this issue and as CPitts says a reflash to the ecu is the way to fix this issue. Your AFR will be all over the shop with the stock tune.