wrecked

I'm hoping it can be fixed with a tune..

wrecked

I watched this video the other day! I don't understand why anyone would want this car in a soft top version when the standard vette has a hard top that's easily removable and fits nicely in the trunk.. lol

Saki GT

The Corvette, with a 5.7 L V8, has a 24 lb flywheel. The AP2, with a 2.2L 4 cyl, has a flywheel that is 22 lb...

Is the Corvette flywheel heavy or light?

The weight of a flywheel effects how rpm change since its an energy storage device. More mass = more storage, and more storage = more time to change rpm. It depends on what you want from the car. Heavier = stable, lighter = responsive.

DBW can be programmed to hang to improve emissions - like the Civic had that was well documented. If you've experienced DBW hang, its an annoying disconnect that is very distinct from a flywheel imo. It is really annoying when you need to creep up at an intersection and the DBW causes the car to surge or hesitate because the emissions system is "regulating" the engine.

Elistan

Oh, oh, I know the answer!
Heavy!
I'm running a 9 lbs Comptech flywheel. It's just right. I dislike the OEM flywheel in AP2s.


Are we all talking about tow different phenomena, though?

First, there's the "rev hang" when the car is put into neutral and the engine revs don't begin to drop until after a bit of time. (This appears to be a DBW/IACV tuning thing?)
Second, there's the engine revs falling slowly once they do start to fall. (This appears to be a flywheel weight thing?)

The AP2, IMO, was flawed by being subject to both issues.

Anyway, going back to re-read it, the way wrecked worded his question now makes me think he's asking about the first situation, so yeah, probably not anything to do with flywheel weights like my initial post speculated.

rockville

Of course the weight of a flywheel isn't really the metric of interest in this case. The polar moment of inertia is what really maters. That is a function of both weight and where the weight is located. Of course that information is rarely published.

Saki GT

DBW will hold throttle open or closed, thus keeping rpms where you don't want them, and you can't manage it unless you find a CPU reflash, vs a flywheel, which you can manage and change, and which has a more natural feeling, even if you do or do not like its characteristic based on its weight.

Only 06+ - 04-05 do not have DBW and you can replace the stock flywheel with a lighter flywheel - AP1 spec (12 lb) or lighter like the 9 lb Comptech. Although truth be told, I could not really detect DBW when I drove an 06 - it certainly wasn't as bad as the Civic Si with DBW or other cars I've driven with DBW.

Elistan

The 04 AP2 I owned for a year, even without DBW, most certain had the rev-hang when shifting issue. So yes, both issues.

Saki GT

That at least is easily fixed - either adapt the driving style to work with the heavy flywheel, or swap it out.

When DBW needs to be changed, you either need the OEM to provide an update or buy a reflash on your own, if either are available.

Chris S

Too much stiction in your throttle cable?

rockville

The "throttle hang" on a non-DBW car can come either from a computer controlled idle air bypass valve (as it was in my Contour SVT) or via a damper that slows that last bit of throttle closing. I believe one of my older Toyotas had such a damper.

The "hang" isn't the result of the throttle plate not closing right away. Instead it doesn't fully close for a second or so. Thus instead of 0% throttle you are at perhaps 5% for a second which is enough to slow the drop in engine revs.

Regardless of the reason why it's annoying.