Dynamic Airflow Transition Lean

[realcanuk]

Interesting stuff. I wonder if any effect when running MAF only.

[ttz06vette]

I'm thinking maybe during transients.

[schpenxel]

Very interesting. I've been wondering how that works.. not that I actually understand it any better now, but I can pretend I do.

[Michael_D]

Well after a few days of farting around with the car and logging PIDs, I just don't see where this has 'helped' anything. Actually, it may be causing some funkiness with burst retard. I am getting burst retard kicking in a hell of a lot more than before I zeroed these tables out. No idea why. I did not hook the WB up either....(PITA with a cable strung through the widow). I am going to populate the tables with the OE values again today, and do some comparitive drives to see if this burst KR problem is coincidental, or if these tables did cause it.

[10_SS]

I noticed now in PE WOT above where I end Dynamic VE which is set to stop at 2500rpm.. my AFR seems allot less smooth and more lean than it was before... but not sure if this is the cause or not.. .just something i noticed. I also played with some Transient Fuel Mass Gain Impact Factor Gas/Gain... before this and it somehow made a rich spike right around 3300-3500... during no transient. just WOT// so went back to stock there. So these tables seem to do strange things.. for sure.

[schpenxel]

I've never been able to get a smooth AFR using the MAF only on my car. Look at the MAF signal and see if it's bouncing around a bit.

VE/SD only worked much better for me

Yeah the transient fuel stuff will do some weird stuff. I never have gotten it even close to right.

[Michael_D]

Well I repopulated the dynamic coefficient tables with the stock tune settings and spent a couple hours putting the car through the same acceleration tests as before with the tables zeroed out. To be maybe a bit more clear, I would accelerate in each gear without going into PE. Fast romps, but using only about 30% throttle - if that makes sense.....

Burst KR would kick in like freaking crazy with the tables zeroed. And not just kick in and stay, but kick in and pull spark, then decay quickly, then kick in again. I felt like a bobble head doll, it was imitating as hell. So with the OE settings, I still see burst KR kick in, but not nearly as often, and it will decay and not persist. Can't even really feel it.

So I dunno. I'm scratching my head trying to imagine why this would happen, and I'm also beginning to believe I am imagining this. Doesn't make sense. But the logs show it, and I definitely felt it. I sure would appreciate one of you super-tuners that understand this ECM to tell me I'm either nuts, or why this would happen.

[Higgs Boson]

I have burst knock zero'd out and still also experienced timing cuts. I am just going to leave it stock.

I can't get the TPS tables back to stock. Some of the stock values are 1500 or 1600 and the limit for editability is 1.00....is there a decimal problem or a limit problem? All the others (MAP, base, etc) are much smaller numbers like 6 or .9, etc.....

[ttz06vette]

I went to an Abaco MAF and it smoothed out my signal immensely. The hardware itself helps plus it allows for signal smoothing within the firmware.

[ttz06vette]

Tested the car today. Ran great with the tables zero' out. I had to adjust my MAF airflow curve a bit and I got some KR on full throttle pulls, but nothing that a little more meth and a drop of few degrees timing didn't take care of. What I like is I set all the transient tables back to stock. I'm leaving it here for awhile to see the long term results.

[edge04]

looks like everyone zero'ing these tables is FI? Is it just more noticeable than a NA set up or is it because most NA set ups are not running a custom operating system?

[schpenxel]

Which tables are you referring to?

[ttz06vette]

Well guys I think I spoke too soon. Like Michael D., I can't get rid of the Kr. Reduced total timing in the area of knock in the histogram and it's still occurring. Weird. Put the stock predictive table back in and it's gone. I decided to go back to my original tune until I understand better how these tables work in conjunction with MAF.

[edge04]

Which tables are you referring to?

the predicative coefficient tables

[schpenxel]

I'd say most are just running speed density with FI

I've never been able to get rid of all KR when running the MAF--not sure why since it's not a problem in SD

[Michael_D]

Just to clarify, I am using the HPT custom op system. I am using it, because I got fed up with trying to calibrate VE Coificients with a third party Ap. I wanted a real VE table, and I want to use a blended MAF/SD air model.

I wonder though.....

If one were to zero these coif tables out first, then cal VE and MAF....... they may not have the issues I was seeing? I'm tired of experimenting though, so I wont figure that out. Time to just drive this damn car and stop fussing with it. It's become a bizarre obsession for me......

[DSteck]

Zero out the burst knock if you're going to zero out the prediction coefficients. Part of the use of the predictive model is to smooth the values generated by the SD side of things so as to not constantly trigger burst knock. With no predictive model, there's no filtering, which means there will be very rapid changes to cylinder load almost all the time. Run a car in pure SD, and you'll see burst knock trigger constantly. We don't have the tools to properly calibrate the prediction coefficients, which are dependent on each engine's specific setup, so kick burst knock to the curb.

[Michael_D]

Oh good. I’m not imagining things….. Thank you for the explaination Dave. You should write a book.

I am in somewhat of a conundrum now. I think I understand how these tables work a bit better. Small problem with disabling burst knock though. I recently discovered that with it disabled, I was getting all kinds of KR whenever I would downshift and stab the throttle (but no KR if I ramp up rpm in the same spark table cell). With it enabled, I get none. I have PE enable functions about as aggresive as I can set them too....TPS starts out at 20%, and ramps down to 5 at 4000 rpm. Fuel where I live makes it challenging. Our premium is 90 octane, and I suspect it’s probably more like 88 or 89. I have not had much luck with octane additives in the past, but in all honesty, I have not tried any since back in the early 2000’s.

[Higgs Boson]

sounds like a simple case of too much timing.

[edge04]

so do you need to zero out multi burst tables or just one?