Trans Question

[04MEMA]

Need feedback from members please. Tonight I was in the MM idling, let off the brake and 1/4 pedal down the gas and immediately come off. Car lunges and after that has kind of this delayed event. It's not a thunk, it's kind of weird. It's like a delayed acceleration that just kind goes "push" that happens a moment after I let off the pedal. Kinda like after the pedal is released something gives the car a nudge. What's happening? Is there built up energy/inertia in the torque convertor that's being released? I'm surprised I didn't notice this before. Is this normal? Or can some folks try it in their cars?

I noticed it first after my garage door opened and I gave a little goose - driveways on a slight angle upward. After I noticed it doing this I immediately pulled out to level road and repeated it several times. Curious. Car seems fine - If I floor it from a dead stop it reacts totally normal.


Thanks,
Jeff

[TripleTransAm]

I noticed the exact same thing on my car, and reported it to my dealer back in mid 2003. The assessment was that it was 'normal', although I can't really say I'm impressed with any tranny that acts this way. Then again, it wasn't my usual tech riding with me, so perhaps I should bring it up with him and get his opinion on the matter.

I'm thinking it could be a matter of some sort of pressure spike in the tranny because of the quick goose of the throttle... or perhaps it's some sort of side effect of the looser torque converter (although you have an '04... we don't share TCs)... or perhaps it's some sort of driveline lash that takes up then slacks once again (lash within the tranny, U-joints, diff gears, etc.). Anyone who's driven a fuel-injected manual tranny car will appreciate how annoying it is to set up a bucking oscillation at very low road speeds and RPM (ie. no engine braking): lunk-THUNK-lunk-THUNK-lunk-THUNK- back and forth, back and forth, etc...

[04MEMA]

Yeah this is probably just a little lack of refinement here, not a big deal. You know I'm installing my S/C next week and want to have confidence that this isn't a disaster waiting to happen. Thanks for the feedback. Regarding the driveline, I noticed in many of the MM's I test drove as well as in mine a drive line "click" when you come in an out of torqueing it. Could be u joint/trans/axle - not sure but again a little unrefined, but I don't expect this car to have Lexus refinement. All that said, I do love this car big time. :banana:

Jeff

[David Morton]

I think it's shifting to third while the convertor is going to 100% at the same time. That's what it feels like to me. One of the guys with an OBDII hand held could do an "event snapshot" to confirm this. Nothing to worry about. You've got an '04 with the "good" transmission.

TTA, what you describe on the manual tranny is caused by the spring dampeners on the clutch disc. Every MT car has a place where drive ratio, gear and RPM's will have those pulses of torque from the crankshaft timed just right so we can have a nice joy ride for the kids!

[TripleTransAm]

Seems awfully early (and low speed) to be grabbing third, I'd say (unless I'm not experiencing the same thing as Jeff).

In my case, it was on my old driveway, at a slight incline. I was just goosing the throttle to get it to inch up the drive just a little bit (I guess I might have been in a hurry, since I never shock my driveline like this for no reason). The result was a delayed "stumble", if I recall correctly.

Essentially, the car was at rest, you release the brake, and just goose the throttle, and immediately lift off. We're talking a very light stab... you're practically already off the gas by the time the motor even has a chance to react! However, the car does lurch forward, but then there is some sort of shudder or a sort of thunk. It really almost feels like massive slippage, then grabbing... imagine an old THM350 low on tranny fluid and how it would feel coming to an abrupt stop and having the tranny slip into 'neutral' briefly before thunking back into gear once you gave it some gas, although in this case there is no RPM rise because you're already off the gas when the weird 'slippage' happens. Best way I can describe it...

I haven't experienced this since bringing it up a year and half ago, so I wonder if it's still there. I might try to reproduce it this coming weekend....

[Krytin]

The tranny could be hitting 2nd gear or like dave says the TC clutch could be ramping up to 100% cycle. I also agree w/Dave about the MT low speed "dance", I had it w/my '68 Cougar XR 7!

[TripleTransAm]

That low speed 'dance' is the reason I upgraded to the Marauder... I was going NUTS with my Civic in stop-and-go traffic.

Many manual EFI cars shut down the injectors, or at very least bring down the duty cycle to something extremely low when on deceleration at a significant RPM, usually in the lower gears. (the side effect is an extremely nice exhaust note on deceleration, especially if you have a good exhaust system). The systems are also programmed to 're-light' the injectors at a preset RPM, to avoid stalling or other nasty effects (emissions? overheating the exhaust?). In the case of my WS6, this RPM is around 1000 RPM... maybe 1100 RPM... barely over the 900-1000 RPM idle speed. You can *just* barely feel a slight surge as the engine slows down in 1st or 2nd gear to idle speed.

The Civic, on the other hand... as much as I am totally impressed by the flexibility of the Honda powertrain and its efficiency, someone really dropped the ball on this aspect of the engine programming. The 're-light' point was at something like 1500 RPM. With the gear ratios the way they were, I was *constantly* hitting that point in stop/go highway traffic. For instance, accelerate in 1st to around 2200 RPM, let off the gas, the injectors shut down, the car decelerates down... down... down... to 1500 then the injectors came to life and the whole car started oscillating more and more violently. Getting back on the gas at this point (however lightly) would result in a violent end to this bucking, until it would once again see itself in a situation requiring fuel shutdown on coastdown.

It seems to be a Honda-thing, as I've had many coworkers and friends with EFI Civics from the late 80s to present day ask me about it. Nothing I could do about it. P*ssed me off, and really started me thinking of replacing it with something more fun (and the rest is history).


Side note: I used to use this fuel shutdown feature to my benefit, on my WS6. Not only was the exhaust note pure heaven on the way down from 2500 RPM in 2nd or 3rd gear, but the exhaust would heat up accordingly. Any application of throttle at this point would re-light the injectors, and the result would be a POP out the exhaust. If I lightly tapped the accelerator during this deceleration, it would generate said pop, followed by several smaller pops decreasing in intensity... very hot-roddish ("baaaaaaarrrrrrrrrrrrrrrrrrrrrr *POP* *pop* *pop* *p* *p* *p*....."). I don't do it anymore, since having added my unmuffled tail pipe to my 1998-specific single outlet exhaust system... when it happens it sounds more like a gunshot than an exhaust pop.


Back to the thread topic: if this WAS my TCC locking up at barely-moving driveway speeds, I'd be PRETTY worried. So I don't think that's it.

[Krytin]

My '68 Cougar would buck like a mule in 1rst gear if you jabbed the accelerator and let up on it right away. 650# springs in the clutch plate hub & a big fat foot (13 EE) were the cause - I sank back into the seat under acceleration, as I slid forward under deceleration my foot would hit the gas pedal and start the cycle all over again!! Not only embarssing but you're head would snap back & forth hard enough to give you whiplash!! In retrospect it's pretty funny and I'm having a hard time typing right now!

PS: I could not replecate you're problem w/my MM. That doesn't mean mine won't do it - just that maybe I'm not understanding the situation.