ULTM8Z

Another curious one with a (at least to me) little unclear description in Tunerpro...

"Used to Lag Filter 0x0071=kPa MAP for AE MAP determination"

Is this kind of like the TPS AE lag filter, but with MAP?

Factory value is .023.

Also, if I raise the value does that mean a larger AE pulse width? Or vise versa?

ULTM8Z

Played around with this earlier today... moved it up and down by 50% both ways and didn't really detect any difference either in seat of the pants or on the WB. So I'm not sure what this parameter really does.

But, the modification I made to the AE delta MAP from post #3 in this thread https://www.thirdgen.org/forums/diy-...fast-o2-r.html is still a significant improvement in seat of the pants feel.

If I even breathe on the gas pedal now the car really wants to go... GM's AE delta-TPS values from the DA3 LT1's seems to be right on the money. But the AE delta-MAP seems to be too rich, hence the improvement by leaning out the coolant modifier by ~20%. Though I'm still confused on what the parameter in the subject of this thread really does now after experimenting with it.

It seems to be the case that the throttle transition is the sharpest when you don't get a huge dip in AFR. In that other thread, the AFR's I get at part throttle acceleration... when I get into an AE event now, AFR drops to ~13.5 and stays there with the updated O2 swing points. As opposed to dropping into the 12's and then recovering to ~13.5. While the seat of the pants feel difference is nothing more than a split second after the throttle change, it's still a noticeable thing. Like I said in previous posts, the AE seems to "set the tone" on how the engine follows through after the AE event is over.

I also reduced the maximum delta-MAP value by 17% (.258 down to .220 at 50 kPa delta-MAP). This also had a noticeably positive effect, but mostly off the line with hard throttle launch. Again, I don't get such a large instantaneous AFR drop, and that reduction in the AFR drop results in a sharper, more "neck-snapping" hit when I punch it.

Dominic Sorresso

I find that keeping delta AE values on the leaner side results in crisper throttle response.

ULTM8Z

Yeah the Miniram seems to like a very quick large shot of AE from the delta TPS just enough to deal with the throttle change. But a large lingering shot of delta MAP AE seems to cause sluggishness.

84Elky

Yes, AE-TPS and AE-MAP lag filtering are similar.

But note, it's generally best to not change Lag Filtering Coefficients because they're designed for use in detection of subtle changes in engine states. These changes are then used to make important decisions. In the case of 0x57C, the difference in the old and new filtered values determines the degree of change in kPa. After many calculations, the invocation of AE-MAP may be affected but not always. It depends upon the calculated kPa differential. But the larger the filter coefficient the greater the new lag filtered value and thus the change.

The preferred way to affect AE-MAP is described below (from my AE-MAP document which will be republished soon):


Elky

ULTM8Z

Resurrecting an old thread of my own here...

I notice there is now a 2nd AE delta MAP filter and I'm wondering how they play together.

AE-MAP, RPM Lag Filter Coefficient

Used to Lag Filter RPM/12.5 before using it for AE-MAP determination calculations.
Factory Default = 0.039 (3.9%)


AE-MAP, SCALED MAP A/D Lag Filter Coefficient

Used to Lag Filter 0x0071=SCALED MAP A/D which is used for determining if AE-MAP is to be invoked.
Factory Default = 0.023 (2.3%)

Also, what does A/D mean?

ULTM8Z

Lol... I don't know exactly what I did here, but the engine is very happy about it...

I've been playing around with the lag filter coefficients... What I settled on via a lot of iteration is....

AE-MAP, SCALED MAP A/D Lag Filter Coefficient => Factory: .023 New setting: .100

AIR FUEL Param, Coolant lag filter coefficient => Factory 6.27% New setting: 100%

What I'm noticing is more consistent behavior during throttle transitions from one time to another, and across coolant temperature variation. It's subtle but noticeable. Back in my original post in this thread, I hadn't yet gotten the ignition timing dialed in the way it is now, so the lag filter changes are having a very noticeable effect now

Between this and the ignition timing discovery, it feels like a totally different car than from just a few months ago... and I thought I had it dialed in well before.

During a free-way on-ramp blast coming home this morning, I was going through the gears with the gear vendors and inadvertently skipped over 2nd gear (went from 1st-over to 3rd). But I didn't realize it at first until I looked at the shifter and realized I was in 3rd gear. The additional power it had in 3rd gear coming off the shift, actually masked the skipped shift... whereas before I would have noticed a huge bog if i did that.

Historically, I've found that the Miniram really seems to prefer to de-emphasize AE Delta-MAP and emphasize a very early and large AE Delta-TPS pump shot... with AE overall tapering off very quickly. I'm guessing the above modifications are continuing that trend?

ULTM8Z

Continuing to dabble in Tunerpro with the AE scalars (there are a lot more than in Tunercat), as I read and re-read Elky's AE document and reconcile it against seat-of-the-pants results in real world testing. My running theory about how the Miniram likes a very large, immediate and short duration AE pulse is continuing to be proven correct (in addition to de-emphasizing delta MAP AE and emphasizing delta TPS AE). While the Miniram likes a lot of AE, if the AE pulse lingers, it can generate kind of a laggy feel to the throttle. The critical time period where AE is critical is the few milliseconds when the throttle transition just starts to occur. After that, you want the AE to go away quickly and revert back to normal fueling ASAP.

On the Delta MAP AE side...

I actually have my AE delta MAP decay rate vs coolant set to 85%, up from the stock 46%, nearly a factor of 2 faster decay rate than the factory.

I also have the AE delta MAP AE vs delta MAP table itself leaned out by ~35%

Lastly, AE-MAP, SCALED MAP A/D Lag Filter Coefficient => I've bumped it up to .250

Everything else coming over from $DA3 works good as is from the factory calibration.

On the Delta TPS AE side...

There are number of $8D scalars with no apparent equivalent in $DA3 (at least in any of the available XDF files I can find). Most of the $8D AE tables have equivalent $DA3 tables whose values can be copied and pasted directly from DA3 to 8D with excellent initial results, which has been my starting point for quite some time now). It was a huge time saver being able to leverage the R&D that GM had already done for short runner manifolds. But some fine tuning of these can produce remarkable improvements... probably because the 8D scalars were meant to go with the 8D tables. These scalars need to be customized to optimize the effectiveness of using DA3 tables on the Miniram.

I have the threshold for triggering Delta TPS AE set to the minimum of .39%, down from the factory 3.13%. It may not seem like much, but it makes a significant difference on the Miniram, again during those first few milliseconds of throttle transition.

I also have the "AE-TPS, Forced Index for Entry into Pump Shot Table" set to 0. This forces the ECM to always go to the first row of the AE delta TPS PW factor vs Async pulse table. If you compare this table between 8D and DA3, you can see even GM followed the same philosophy. The 8D table has AE lingering around for the entire 8 rows of the table, whereas DA3 is more heavily front loaded on the first two rows and then goes to 0 from rows 3 thru 8. Again, by setting this parameter to 0, I get the heaavy shot of delta TPS AE no matter what, which was the intent of the DA3 Async table.

I also reduced the duration of AE Delta TPS- by virtue of the number of distributor reference pulses (DRP)- from 12 to 8. This again goes toward the philosophy of a large, heavy shot of AE that disappears quickly.

The AE Delta TPS filter coefficient table varies with RPM in 8D, where it's .063 for all values. In the DA3, it's only a single scalar at .141. So I simply modified the 8D table to be .141 everywhere. It seems to work really well with the other AE delta TPS tables.

The rest of the DA3 AE delta TPS tables seem to work good as-is.

Also, don't forget to increase the maximum allowed AE pulsewidth. Factory 8D is 5.55 msec. For DA3, its 15 msec. So I set mine to 15msec. Otherwise, this parameter will truncate whatever increases you program into the other tables.

Also, to keep the ECM from adjusting fuel trims based on momentary AE fueling, a couple of things are needed...

Set the flag for "Reset Integrator when AE in progress'. This will keep the ECM from adjusting fuel trims (INT and BLM) as a result of AE fueling.

Also, the table for "Closed Loop Fuel Integrator Delay vs Airflow" benefits from slowing it down a bit. GM has the integrator responding in a couple hundred milliseconds to a rich/lean condition. During AE, by definition you're going to be a bit rich, so I increased the delay to about 1.5 seconds. Again, I don't want the ECM thinking the momentary rich condition is something it needs to pull back to ~14.7:1 AFR. It may seem redundant to setting that Reset Integrator flag, but it does seem to help.

Any rate, just some tuning tips I'm continuing to learn about.