I'm trying to understand what this scalar does in TP. It's set to 3 counts from the factory for AUJP.

Elky, I have your AE document, but I'm not quite following (I'm not very strong on code). Basically in plain English what happens if I raise or lower the value?

It looks like it has something to do with how the ECM invokes the table AE TPS-6.25ms TPS Change Factor (for Pump Shot). Or in Tunercat, it's the table AE Delta TPS PW Factor vs Async Pulse.

 

What's this document form Elky? I too am struggling with my AE. I have adjusted the ms in my AE vs. TPS and AE vs. MAP (Running EBL) and I am still getting a lean spike. Less than before in duration and magnitude, but I still have it and now it swings rich on the return. So, subscribing here as I am also having AE fun.

 

Elky's document is only for 90-92 $8D AFIK.

 

ULTM8Z ---
Your post is most timely. I've been working on AE lately and have revised the document, have clarified some things and de-hexed it a bit . But hex is needed to reference XDF items as you did because XDF descriptions differ. I'm planning on releasing the revised doc in a day or so. And yes, while it specifically applies to $8d AUJP, the concepts apply to virtually all GM OBD I masks (SD and MAF) because the principles are virtually the same. It's just that early MAF applications that do not use Speed Density only have AE-TPS.

Now regarding your question, we first need to get the terminology straight. The Scalar in question is that at 0x539=AE-TPS Forced Index for Entry into Table L853B (0x03). And yes it becomes an index into the AE-TPS Pump Shot Table at 0x53B under one condition. It's complicated, but here's the short answer:
- To enter AE-TPS, only need to have a 6.25ms TPS% change > 1.17 (0x52E=AE-TPS Min 6.25ms TPS Chg to Invoke if NOT in AE-TPS (0x03=1.17%)
- But once AE-TPS is invoked, the code starts checking for a change in 12.5ms
- If while AE-TPS is active and the 12.5ms TPS% change exceeds 3.13 TPS% (0x538=AE-TPS Minimum 12.5ms TPS% Change Threshold (0x08=3.13%) Was and not correct: AND the index value is <= 3 Correction: AND the index value is > 3, the item you reference (0x539=3) is used to force the index into the pump shot table to 3. This means the first 3 elements (0-2) of the table will not be accessed until AE-TPS is exited and re-entered. Only elements 3-7 will be accessed.

Now, why is this done? Only GM knows, but as you look at the pump shot table, GM chose to use a factor of 3.984 in the first element (the largest allowable), and 0.5 in all the other elements 2-8. This means the first AE-TPS pump shot will be the largest. A factor from this table is multiplied by PW at the time to determine AE-TPS PW. And if TPS% is increasing more than 3.13 in 12.5ms, GM likely determined that a TPS% change that large would invoke AE-MAP so there would be no need for any additional AE-TPS in large amounts.

Regardless the reason, that's what happens. Given the above, you can see where you will be introduced into the pump shot table to extract a factor should you choose to change the value. Allowable values are 0-7.

Frankly, I wouldn't change it. Rather, I'd increase the factors in elements in table elements 2-8 if more AE-TPS is needed, reduce them if less. I'm confident GM had a reason based on testing for setting it =3.

HTH, Elky

 

Elky,

Interesting... very interesting. So with the value of 3, you're saying that when the ECM re-enters the pump shot table on the 12.5 ms change, its actually starting with row 3? So the first pump shot that gets delivered is actually .5 and not 3.984?

Now that is very interesting indeed because I'm running the DA3 AE tables and the DA3 pump shot table actually goes 3.984, 2.00, and then 0 in every other cell thereafter. In which case am I not getting any AE TPS fueling if I re-enter the pump shot table on a 12.5ms change.... I'll have to play around with this and see what it does.

Thanks for the plain english explanation! It actually made it through my thick mechanical skull! Lol...

 

Yes, that's what happens BUT ONLY under the conditions outlined:

 

So after it goes to position 3, does it proceed to use 4 through 8 before if finishes?

 

Yes it does. And once the index reaches 7, it remains at 7 accessing the last element of the table until AE-TPS is exited. But remember that AE-TPS happens in a heart beat. It's here, does it's thing with the largest effect when it begins and is gone. It can last no more than 12 DRPs (0x530=AE-TPS Done if Counter Equals 12 DRPs). At 2400 RPM, 12 DRPs occur in 75ms. AE-TPS is exactly like the accelerator pump in a carburetor. One big shot of fuel, some dribbles and adios.

Addition: After the index is forced =3, the DRP counter is reset =0 causing the AE-TPS DRP count to restart. This has the effect of slightly extending AE-TPS until 12 DRPs are counted, where it is exited.

 

Just a thought if you want to see what happens in $8d with AE-TPS variables (Table index, DRP counter, & AE-TPS PW), it's easy to log them. Use the attached ADX and make following changes to your BIN by changing 4 ALDL Reporting Scalars:
You'll only need to create an AE-TPS Test BIN from your BIN by making the following ALDL reporting changes in the XDF:
- ALDL, Word# 49 Distance Travelled MSB-----Change from 3085 to 30FA to log AE-TPS PW (MSB)
- ALDL, Word# 50 Distance Travelled LSB-----Change from 3086 to 30FB to log AE-TPS PW (LSB)

- ALDL, Word# 31 EGR % Duty Cycle-----Change from 011D to 00A2 to log Pump Shot Table Index (0-7)

- ALDL, Word# 16 NV Ratio-----Change from 0140 to 00A3 to log the DRP Counter (1-12)

These changes will report the above variables using your BIN and the attached ADX.

A log file from my test is also included.

Elky

 

I played around adding a little more to row 3 through 7, and it actually felt a little more sluggish. I think the DA3 AE tables add sufficient amount of fuel, such that if I add more, I get a little lazier throttle response. I can see it on the WB...

As of now with the DA3 AE tables, the WB seems to show very a very minimal drop in the numerical AFR value (i.e., AFR doesn't drop to 10:1 on throttle changes). It'll drop about 1 point from whatever AFR I'm starting at before the delta-TPS/delta-MAP event. You can feel its right because the response is so crisp and linear...

Although I'm continually curious about some of these more "mysterious" AE parameters in Tunerpro, I'd be surprised if any changes resulted in an approvement...