Can fellow owners help me diagnose something?

Ever hammer around a corner and have the car hesitate/studder for a moment, then have the power come back on? Somewhat similar to driving a 350Z or Mustang GT with traction control on - but not quite as a dramatic power shut-off.

Situation 1:
On the track. Braking into a turn, downshift to 3rd, let off, apex, then acclerate hard out of it - but almost feel like you have to fight the car a little. Almost like the traction hesitates and studders a second, but there's no noticed wheelspin.

Situation 2:
On the street. Took a corner and hammered the throttle in 2nd trying to get the rear to slide out. Instead got the 'almost studder' feeling again.

Situation 3:
On the track. Taking an 'S' curve. First left, then right and hammer the throttle to 'gas out' and will usually drift towards the outside in 4th gear. A few times had the car like cut all throttle response for a brief moment. Not sure if the ACD is trying to sort-out possible traction loss?

The front differential in the IX is a Helical Front Limited Slip Differential, so is this what I'm feeling as it adjusts to the situations at hand. Not sure what it feels like if you run up on 3 wheels and tripod? I can't imagine that even happening in 4th. Plus in all 3 situations, I'm under hard acceleration - not braking. Running stock suspension with the Hotchkis Rear Sway set on medium - nothing weird. Always run the ACD on the Tarmac setting.

 

ttt; I can't be the only IX on the track.

 

What's your fuel level on the track? I've had a similar feeling in my 05'. It always when I want to power on early through a turn to get the car into a drift and it feels like something is confused in the drive line. Hasn't happened in awhile though and I think it's because I've adjusted my driving style to keep this from happening. Have you ever noticed how the cars' line will change dramatically if you lift a little mid corner? I'm not talking about plowing through a corner either, but accelerating through a turn and then backing off some. I attribute this to the ACD as well. Never had a car that would tighten up so much when coming off the throttle. If you are not prepared for it, it can be frightening.

 

Fuel level in both cases on the track was probably under 1/2. In one case I know it was pretty low, but really doubt it's going dry as there's tighter corners that I hit, just maybe not under the 'meat of the power curve' as such to induce a small drift I think.

And yeah, if you lift mid-corner, the car will definitely change lines. Depending on how hard you were going in, it could tighten like you said - or if it's like downhill (like an off-ramp circle) it could start plowing to the outside because of the weight shift. The latter can be very scary!

Anyways, sounds like you may have felt it too? But no idea either eh.

 

Your inside rear wheel is off the ground. The ACD is thinking, "okay which wheel should I send the power to?".

When I first got it I asked corner workers if it was off the ground. Their reply was yes.

 

I don't think that is what is happening. ACD controls front to rear torque split and for the rear we (USDM) have a clutch type mechanical LSD. The JDM and EDM versions come with S-AYC that controls the left and right rear torque split. In our case if one wheel goes up in the air, it will spin with the same speed as the other wheel in contact with the ground. I have lifted my rear wheels lots of times going around corners and haven't experienced what you guys are talking about. I'm wondering if you guys are hitting boost cut or something, since it seems you aren't getting fuel cut. Fuel cut usually happens when you have less the a 1/4 tank of gas on the track and are taking high G corners. Do you guys have a reflash done to your ECU?

 

I was thinking a possible misfire from old plugs, but it'd happen in a straight line also.

 

My mods are in my sig, yes I've got an ecutek flash. I've had this happen with a 1/2 tank, so I'm not sure of your gas theory. I really doubt I'm hitting boost cut, I've never had spiking in this car before or after the flash. (AMS does my work.)

You say you've lifted a rear wheel, but is that in a IX? I'm referring to the newer ACD setup here.

 

do you have any datalogging equipment? that would be an easy way to try and determine if it is an eng performance issue or really a suspension set up.

 

Nope, I'm low-tech.

 

At this point the best way to figure out what is going on is to datalog. I'm not sure you can use the tactrix cable because you have an ECUTEK flash, you might have to datalog with another means.
Yes it is true that the ACD did get upgraded/re-coded but I believe it was only for the JDM and EDM models to make better use of S-AYC because S-AYC wasn't properly being utilized when they would get wheel lift from the inner rear tire. I don't think ACD changed for the USDM model.
BTW, I drive an 05 EVO8 MR ...

 

THIS sounds like a similar problem, so might be of some help.

 

That's a different circumstance. Sounds like this is happening when he's braking and it lasts a few seconds long. Also he mentioned it unbalancing the car.

My situation is when powering out and doesn't unbalance the car. It literally feels like an lsd dials down the power to like 50% for a brief moment and then it comes back on. Like if you popped the clutch in a reardrive car that had traction control on.

 

Uhh I dun think your ECU needs to be reflashed again heh...

Have you got your car aligned? Just asking if you know what settings your currently running.

 

I've run eleven track days this year on 4 different tracks in my RRE coilover equipped IX MR and never experienced anything like you are talking about. I have a Vishnu ECU reflash and a quiet turbo back exhaust. My car runs amazing at the track. Sounds like you have an ECU/Ignition/Fuel problem. Are there any tuners in your area that can give it a "test drive" to duplicate the problem while runing a datalog?