Sluggish around idle

[BlackSTI]

Hey Guys,

Just want to throw out a problem for any suggestions. Sorry if my description is vague, trying my best to describe it.

Comparing my car (07 GT tbSTI) to my brothers My 08 GT, down low the revs seem to behave very differently. He can basically be doing a wide range of revs when releasing the clutch and it all seems fine with everything seemingly sycning up. Mine there is a very fine sweet spot to get in to first gear from standing, I will either have the revs die out on me and nearly stall or rev far too high and risk smoking the clutch. I have compared both cars after driving both on the same night. Mine also has a tendency to stall a lot easier, I especially notice this while basically idling over speed bumps etc (still in gear).

I think (can't always trust my memory) my car has been doing this since I received it (originally had a ChipTorque tune, which apparently caused me to have to get the heads redone and at the same time a new clutch put in). Matt put a different base tune on semi recently which I think improved it slightly, but its still not comparable to my brothers car. I think Matt's changes have just smoothed things out a bit.

So I am wondering what the cause could be the clutch, tune, something else mechanically? (Hopefully no one tries to blame the human element, ie me).
(I still think its amusing when Matt drove my car he stalled it!, but I understand each clutch is slightly different).

[bigBADbenny]

Log the L & R VVT angles during that sort of driving.
If they are out if sync it can make the car a bit stumbly off idle.
Another way to test it:
Can you indefinitely hold 1500rpm at idle, either in neutral or in gear clutch in?

[BlackSTI]

Log the L & R VVT angles during that sort of driving.
If they are out if sync it can make the car a bit stumbly off idle.
Another way to test it:
Can you indefinitely hold 1500rpm at idle, either in neutral or in gear clutch in?

Thanks for the suggestion Benny, I think in the past I've logged them and they have been in sync, but will check again tomorrow. In the past I've held it fine at a particular rpm, but will try again tomorrow. What will happen if there is an issue? Will the RPM just move around a bit?


I think I need to go on a meet and compare it to some more libs

[bigBADbenny]

It will shudder and stumble, revs will drop.

How about your inlet: stock everything?

If aftermarket filter: is it sealed well?

[BlackSTI]

It will shudder and stumble, revs will drop.

How about your inlet: stock everything?

If aftermarket filter: is it sealed well?

Inlet is all stock. Stock air filter. Cleaning the MAF sensor in the past hasn't made any improvements.

I tried holding it on 1500 (with aircon on) and it would occasionally go up to 16500 (ish) and then drop back down to 1500 after some time.
With the aircon off, it would hold 1500 constantly.
I will hopefully have some time over the xmas break to do some logging.

[Boostaddict]

Mate I found that my clutch has ALOT to do with the sluggishness of the take off and low speed, just off idle sorta speed.

I have a shit exedy sports organic clutch that is a PAIN IN THE ASS to drive with. Freaking heavy ( other forum member can attest to this ) and rattles and shudders and gives a driveline slap sorta feel.

I will be replacing it with the motor build with a competition clutches clutch , which my mechanic said was good bit of gear for the cost.

[bigBADbenny]

Do you know what your max requested torque percentage is?
On one of my earliest tunes it was too aggressive in sport # and too slack in I mode.
I'd either stall or burn User error didn't help either...
70-80% max requested torque seems to be the sweet spot IMHO.

[BlackSTI]

Mate I found that my clutch has ALOT to do with the sluggishness of the take off and low speed, just off idle sorta speed.

I have a shit exedy sports organic clutch that is a PAIN IN THE ASS to drive with. Freaking heavy ( other forum member can attest to this ) and rattles and shudders and gives a driveline slap sorta feel.

I will be replacing it with the motor build with a competition clutches clutch , which my mechanic said was good bit of gear for the cost.

When I got my head gaskets done, I think I did get an organic clutch put in, I'll double check at home later to the actual type. It was the one suggested by John French, which they have been using for a while now. I do also understand the rattling, which I especially notice the rattling while in gear but decelerating. Maybe this could be part of it.

How long till you get your motor build under progress?

Do you know what your max requested torque percentage is?
On one of my earliest tunes it was too aggressive in sport # and too slack in I mode.
I'd either stall or burn User error didn't help either...
70-80% max requested torque seems to be the sweet spot IMHO.

I don't know specifics like that, but I'll float the idea by Matt and see what he reckons, but this sounds promising! Fingers crossed.

[Boostaddict]

My motor build is taking too freaking long as usual, but should be back end of the 3rd week of Jan if all goes to plan.

But i think my clutch isnt right and it wasnt right from the begining. It was stupidity heavy and very on/off brass button type when 1st installed and my mechanic said straight away that the clutch wasnt right.


From then i have found it sooo hard to get my car off the line nicely, like every day cruising kids and wife in the car type take off.

Can give some berries and slip launch it .... Nnnooo dramas.!!

But that has been done like 6 times if your lucky.!!

[bigBADbenny]

Maybe one of those 1/2 n 1/2 clutches?

Maybe send your clutch to JB for modification?

Maybe a JB clutch?

[Monkey]

BlackSTI, mine is similar with being slightly sluggish from take-off and it's stock (+ cat back exhaust + K&N panel filter) with 73,000kms
I reckon there's a flat spot around 1450-1500RPM - I can hold it fine at these revs when stationary, but when driving I feel like there's a very slight delay in acceleration in 1st gear. Mine idles at around 875-900RPM at operating temperature and is very stable (ie. revs do not fluctuate at all)

Took it to a well-regarded Subaru mechanic in Melbourne and after trying to get it to replicate, he didn't think there was anything wrong with it, so I've decided to ignore.
Is it possible your clutch foot is resting too heavy on the pedal? I know it sounds odd, but my clutch (stock) is very sensitive and sometimes I don't realise that it's slightly depressed until I shift my foot onto the footrest and get a little jump in power.

re: the difference b/t yours and your brother's MY08, I read that the latter has the VF52 turbo but the same power as the MY07 with the VF46 turbo(? ... though it sounds dubious? ). if that is true it would probably account for the torque difference.