HeelnToe

Yea, I know, there's a million threads on hesitation... but my problem seems to be slightly different from what I've been reading:

Shortly after fully releasing the clutch after a gear change at WOT, the engine will "bobble" (hesitate) once or twice for a second before continuing to accelerate.

For example, if you mash the throttle to the floor in first, everything is fine up to redline... shift into second, release the clutch, floor it again...

... and it'll accelerate fine for 1/2 second, then hesitate for an instant, accelerate for for 1/4 second, hesitate again for an instant, then accelerate fine up to redline.

This happens consistently since I've had the car, whether TC/DSC is on or fully off (long switch press), or engine is warm or cold.

I've had the M-flash since day two of ownership (about 4,000 miles now).

I sometimes think the clutch is slipping, but it does fully catch for a second before it hesitates. Doesn't seem right it would catch, then slip, then catch? My foot is entirely off the clutch when it hesitataes.

I've wondered about the coils, but this only happens at lower RPMS, as I start a new gear, and never at high RPMS.

It ONLY happens at Wide Open Throttle. Running up the gears at even 9/10 throttle is fine.

Any ideas? It's going in for an oil change soon, and I'll be sure to have them check into it, as it's easy to reproduce.

Spazm

If you look at some of MazdaManiac's G-Tech graphs, you can see something very similar to that even with the long switch press. It seems like that some semblance of TCS/DSC is still on even after the long press, which could cause what you are feeling.

Is this only shifting into 2nd, or up-shifting into any gear at WOT? Seems like it would do that in 1st gear also, if the computer was worried about traction.

HeelnToe

He describes it perfectly when he says:

Upon reapplication of throttle after engaging the next gear, the power will "bobble" twice in a period of 1 to 2 tenths of a second before resuming normal acceleration.

But where it happens to him at part throttle, it ONLY happen to me at WOT. I'm looking for said graph now...

The TC would certainly explain it, but I haven't read of anyone else experiencing it with the TC turned off. I believe in that thread everyone who turned TC off also eliminated the bog.

I'm not so sure it happens in first, as I rarely stomp on it from a standstill... I usually end up feeding in throttle through first, hitting WOT 1/2-way through, then shifting into 2nd.

Definately happens when going 1-2 and 2-3 though.

Spazm

https://www.rx8club.com/showthread.p...threadid=17220

Here is the graph, and the accompanying thread.

RUmble

What is WOT?

HeelnToe

Thank you! Yup, that's exactly what it feels like.

What I don't understand then is: why isn't everyone on the forum complaining about it? It's a nasty hesitation... you certainly don't need a datalog to know it happened.

I'm mostly trying to figure out if it's a normal quirk of all RX-8s... or something broken on just my car.

I'm beginning to learn towards a) normal quirk, but I surprised it's not a more common complaint.

HeelnToe

(W)ide (O)pen (T)hrottle

Dr. Rx

Worn clutch a possibility?

RUmble

Thanks!

HeelnToe

I've wondered that, but it DOES grip just fine immediately after the shift... it's only a 1/2 second later that it suddenly bobbles, then continues normally.

It's difficult to imagine it being worn at 4,000 miles. I'm sure everyone who destroys their clutch says this, but I really do know how to shift, lol. I never do hard launches... and in fact have never done a clutch dump, etc. The car only had 12 miles on it when I purchased it, so I can't imagine test drivers scorched it.

But it is one possibility that I'm worried about, which is why I'm trying to determine if it's a common problem or not.

w2aew

I don't think it would be clutch related - because after it is engaged, if there was a problem, the engine would rev higher, not bobble.

Maybe a knock sensor is detecting a non-existent pre-detonation (maybe through a resonance), and momentarily retarding the timing? I didn't look at the graphs, maybe that would be captured...

HeelnToe

Let me ask this another way:

Do any of you NOT experience this "bobble" almost immediately after shifting into 2nd (after near redlining in 1st) and going to wide open throttle?

BasenjiGuy

I experience what feels like a surge, if I am running thru the gears at WOT and shifting at slightly less than redline. It feels as the torque momentarily dips and then comes on strong. The engine seems to be firing correctly; it's just that there's a dip of power delivery for a moment and then the rate of acceleration increases back to it's previous level. I notice this when I'm running thru the 7500 - 8500rpm range. If I run all the way up to 9k I don't think it occurrs. This may just be a function of the motor's normal torque curve and possibly a side effect of some aspect of the S-DAIS. Any thoughts, people?

Atacdad

Yes, I get the same thing...I mostly notice it in the 2-3-4 shifts at significant % of throttle. I don't normally drive WOT, nor to redline... but when I'm "gettin on it" up to 7500-8000 rpm, I get the hesitation. My theory is that its something to do with the injection/intake system..when you let off the gas for the shift and then stomp on it, you're probably catching the system(s) reseting from high rpm to low(er) rpm settings and it has to re-open the paths it was shutting down.

Ajax

This is similar to what I was thinking.. If you get up there in revs, and then shift, it's possible that you'll drop enough revs to close the tertiary intakes and the slight bobble would be them dropping to closed and then re-openning.

Rob Tomlin

This sounds somewhat similar to the famed 3k hesitation on 3rd gen RX-7's, with the obvious differences being that they occured only at 3k rpms, and not at WOT. Normally it was worse when the car was cold.

Anyway, this doesn't sound good. In fact, this would annoy me quite a bit. I certainly didnt notice this on my two lenghty test drives, and there was plenty of WOT driving.

StewC625

Mine does it when I run WOT to the redline, shift hard and get that wheelspin "chirp" from the back end - and then I get the blinking skid light and the DSC/TCS puts the wet blanket on the fun for a second or so, and then away we go.

Shutting off the TCS/DSC stops that cold - get a serious "screech" on the 1-2 shift, and the car will jiggle sideways a bit unless pointed perfectly straight! YEE HA!

I think you're feeling the traction/stability control exerting it's morals on your driving.

SC

BasenjiGuy

10-4 to your post, Ajax.

ZOOOMO

I've been WOT'ng it for a whole year once a day thru third gear and the hesitation has been always present until I decided to unable the traction control. Without it the problem completely dissappeared. Remember you need to disable it every time you start your car...

ZOOOMO

Ups, I meant disable

HeelnToe

Yuppers, I disabled it (long press) and it made no difference - it still "bobbles." But the MazdaManiac thread talks about it happening with TC on or off, so I guess I'm not alone.

I rarely do WOT runs, but I just wanna be sure nothing is actually wrong with my car. If anyone else CAN do WOT, redlined shifts from 1-2 and 2-3 without a hesitation right after releasing the clutch and going WOT again, then I have to assume something is wrong with mine. But I don't hear anyone saying they can... yet.

Rob Tomlin

I would think that if every RX-8 had this problem, we would see many more threads on this issue, wouldn't we?

Also, I think that there would be many more people responding to this thread saying "me too" if everyone had this problem.

I don't think that running WOT is a particularly rare occurance, especially for people on this board!

Again, I don't even own an RX-8 yet, so these are just my observations from monitoring this forum. Also, I never noticed the hesitation on my two test drives (plenty of WOT runs). FWIW.

MTCD01

Ok. I have experienced this and have been checking into it further (excuse to make more WOT redline shifts).

I found that the hesitation is easily removed by applying the throttle a little earlier than I normally would. If I apply the throttle the way I would in any other car I get the hesitation (even with DSC and TCS off - long press). I have not been getting any hesitation with the early throttle (DSC and TCS on and off) and can easily recreate it by allowing the tach to dip a little lower.

Just thought I'd share.

MyRxBad

iTrader: (1)

Yes, mine does this as well.
Sometimes between the 2-3shift or the 3-4shift I can see the traction control light flash.
I'll try it with the traction control off (long press) and see what happens.

HeelnToe

So you're saying I don't shift fast enough, huh? Is that it? I don't know how to shift? lol...

OK, I'll try it... I DO tend to baby it a bit when shifting. No more Mr. Nice Guy