nobbyv

Same here. I asked for the TSB, hoping it might help this lag issue, but the dealer said they couldn't find one for my VIN.

nobbyv

Did you observe this ONLY in corners, or did you also try the "slowing almost to a stop, then try to accelerate" test in a straight line?

Strange that this seems to go away in manual mode (suggesting a tranny ECU issue), but those with tunes have reported that the tune also eliminates this (with no changes to tranny ECU). I wonder if those with a tune are simply more likely to use manual mode and so didn't notice that the issue is still there if in auto?

Dr Chill

The lag exists whether going straight or turning. I personally find no relation to steering angle.

nobbyv

Same here. Just wanted to confirm he had tried both.

SMK_RS4

Are you sure? I have throttle lag just sitting still in park and pressing the gas pedal. Are you saying that when you push on the pedal with your foot, the engine immediately without any delay revs higher?

It doesn't matter what mode I'm in, I never get instantaneous throttle response. If you do, then maybe this isn't a software problem, but a hardware problem that can be fixed.

ccap

I too have felt the lag. There was one issue where I went to take a left in front of an oncoming car. I turned the wheel and hit the gas and NOTHING! My heart sank and I thought what the hell was going on, then it took and I shot off to the left but not after full panic mode.

There are issues with this car and throttle lag. My service rep said there were no repair bulletins so nothing they could do.

I guess I have learned the car well enough, that I know "how" to drive the car. This isn't right, and I have concern when my wife decides to drive this car. For example, I put the tranny in dynamic when merging onto the highway. In traffic and needing to jump between lanes or at least to make sure the car wild respond, I put in dynamic.

If there is no traffic and I am just driving, I put it in normal drive, knowing that lag is there.

This is definitely a software throttle mapping issue and it can be fixed. Hopefully they will issue a repair bulletin soon. In the meantime, I just manage the lag

MalibuCANE

Does anyone know if the APR tune eliminates this in D mode? As I mentioned before, I almost got clipped the first time I experienced this trying to get around in traffic and experienced the lag followed by a jump when the power kicked in.

clintb

Any chance this is related to cylinder De-Activation?

The car has to, at some point, re-engage the other 4 cylinders before it can respond with full throttle

.... Just thinking outloud

nobbyv

Just wanted to share some results from some quick testing I did at lunch: this was all done with the wheel essentially straight, and in manual mode. Also, for what it's worth, I have all settings set to "Dynamic" except the seat belt tensioner.

3rd gear: noticable lag when slowing to <2000 RPM, then applying throttle at a constant ~25%. No RPM climb, no acceleration at all for 1-2 seconds. After 1-2 seconds, RPMs begin climbing and car begins to accelerate.

2nd gear: same as above.

1st gear: did NOT observe this lag when in 1st gear. Experimented the least in this mode, as traffic conditions didn't warrant slowing that much. Did three tries, and observed no lag. Can anyone else confirm this result? I'll try again on the way home from the office.

nobbyv

In my experience, when completely letting off the throttle, the car appears to default to 8-cylinder mode. There should be no difference in fuel economy between 4 and 8 cylinders when there is NO throttle applied, as the car relies on the transmission to keep the engine rotating, so neither mode should use any fuel. It's the reason that you're not supposed to coast down a hill with the clutch in on a manual car for best fuel economy; the fuel system must inject fuel to keep the engine spinning if the transmission is disconnected.

Good idea, though, if anyone has any other thoughts by all means post them up!