Liftoff/Tip Out Knock: When to be concerned?

[Phate]

So I've occasionally been getting some FKL pulling a couple degrees of timing when lifting off the throttle at low loads. DAM never moves from 1.0, and when the car is under load the FKL goes right back to 0.

 

While playing around in the snow, I managed to get much higher FKL values (since I was going on-and-off the throttle repeatedly because dorifto).

 

I haven't seen it knock or even really pull timing on me during pulls.

 

How much is "normal" and how much is panic-worthy at low-load conditions, and what can I adjust to make remedy this? Looking through AccessTuner I did see the Overrun correction tables for fuel and ignition, am I on the right track to think that the car is possibly cutting fuel too early, or maybe running slightly too much timing on the transition from high to low load?

 

Is there any harm I could do to it by increasing the fuel cut delay, other than just wasting a slight amount of fuel? Or possibly reduce ignition advance under those conditions?

[Tuning Alliance]

So I've occasionally been getting some FKL pulling a couple degrees of timing when lifting off the throttle at low loads. DAM never moves from 1.0, and when the car is under load the FKL goes right back to 0.

 

While playing around in the snow, I managed to get much higher FKL values (since I was going on-and-off the throttle repeatedly because dorifto).

 

I haven't seen it knock or even really pull timing on me during pulls.

 

How much is "normal" and how much is panic-worthy at low-load conditions, and what can I adjust to make remedy this? Looking through AccessTuner I did see the Overrun correction tables for fuel and ignition, am I on the right track to think that the car is possibly cutting fuel too early, or maybe running slightly too much timing on the transition from high to low load?

 

Is there any harm I could do to it by increasing the fuel cut delay, other than just wasting a slight amount of fuel? Or possibly reduce ignition advance under those conditions?

 

Letting off it is fairly common to get some correction (because it makes noise), i wouldn't worry about it as fuel is already cut and its just pumping air. Timing doesn't matter as its not lighting anything off.

[Phate]

Letting off it is fairly common to get some correction (because it makes noise), i wouldn't worry about it as fuel is already cut and its just pumping air. Timing doesn't matter as its not lighting anything off.

 

Gotcha. I read a bit that it's possible for a weak motor/trans mount to contribute to this due to drivetrain movement/flopping about as well. I'll add some group N mounts to my list of "When it get's warmer" parts.

 

Thanks for weighing in and helping put my mind at ease.

 

Just kinda freaked out a bit when I saw that at one point it hit a value of -8 while I was doing a ken block impression in a snowy parking lot. DAM didn't move though, and when I did a (cautious) pull afterwords everything looked rock solid.

[Tuning Alliance]

Yes, definitely slop in the drive train will increase the noise. Interestingly mazdaspeed DIT cars actually leave fuel on for a bit after you let off. Supposedly to add cooling after a WOT run. So when they have a free flowing exhaust you get lots of noise and popping. Seems like a waste of fuel to me though.

[Phate]

Yes, definitely slop in the drive train will increase the noise. Interestingly mazdaspeed DIT cars actually leave fuel on for a bit after you let off. Supposedly to add cooling after a WOT run. So when they have a free flowing exhaust you get lots of noise and popping. Seems like a waste of fuel to me though.

 

I wouldn't say the mounts are shot, but there's definitely movement.

 

I have a couple of friends with tuned mazdaspeeds, they definitely pop after pulls. Very potent platforms, although 300+ wheel in a front wheel drive car is a bit silly. Fun though.