AE enrichment in the stock chip

E

Eric Stage I

TurboTweak Guy
Joined
May 25, 2001
Trying to learn how the factory handled accel pump shot.

If I look at the stock table "delta tps A.E. scaler of max A.E. pulse width" location 5CF to 5DE. They are all set to 1. Should I assume that the factory program does not use AE based on TPS change (with the car fully warmed up and runtime over 64sec)?

The only place I can find AE happening (car hot) is location 580 to 582, and thats based on LV8 change. Does the LV8 calc have TPS figured in?

Am I reading this stuff right, or am I full of poop? It just seems like there should be some sort of pump shot based on throttle movement.

Thanks,
Eric
 
thinking out loud.......

Studying the code deciphered by Mike Pitts and Scot Sealander on GNTTYPE, I did find where delta tps is apparently used for AE. I was assuming that since there were no entries in the coolant table above 152 degrees, that none was used above that temp. But now I feel that anything above 152 must use the same multiplier as 152, as on the table "delta tps A.E. pulse width mult. vs. coolant temp. " ramble ramble

[edit: I discovered later that the temps are in C and not F, which makes this post pointless...]

I'll get a grasp on it sooner or later...

Eric
 
Eric,
I also played w/ the delta tps to try and cure a roll on knock problem. Had a little success adding a little but its hard to tell. Looking in tweakdos there are 5 entries vs. temp. Its is showing temps in degrees F as the following: 46,89,132,175,218 The values listed for these temps are as follows: .031,.027,.023,.020,.016 this is in bbkj chip. I don't know off hand what conversion factor is used when looking at the hex.

Mark
87GN
 
Originally posted by Eric Stage I
Trying to learn how the factory handled accel pump shot.

If I look at the stock table "delta tps A.E. scaler of max A.E. pulse width" location 5CF to 5DE. They are all set to 1. Should I assume that the factory program does not use AE based on TPS change (with the car fully warmed up and runtime over 64sec)?

The only place I can find AE happening (car hot) is location 580 to 582, and thats based on LV8 change. Does the LV8 calc have TPS figured in?

Am I reading this stuff right, or am I full of poop? It just seems like there should be some sort of pump shot based on throttle movement.

Thanks,
Eric
Click to expand...


I don't think you looked quite deep enough.
There are AE tables at:
580-584 LV8 AE factor vs. delta lv8 above minimum (mult)
586-58E LV8 AE coolant mult. vs coolant temp (mult)
590-598 AE decay rate factor vs. coolant (% change)
5A9-5BB delta tps AE pulse width mult. vs coolant temp
5BD-5CD AE max pulse width vs. coolant temp
5CE-5DE delta tps AE scaler of max AE pulse width
5DF-5E7 max delta tps AE mult vs. engine run time (mult)
 
Thanks for the info guys,

So I conclude based on TurboDaves chart from GNTTYPE that if I wanted to increase the "pump shot" slightly based on TPS movement (maybe for tip-in problems), with the car warmed up (say 190*F, 88*C) and running for more than 64 secs, then I might want to increase the values at locations 5B8 and 5B9 (delta tps A.E. pulse width mult. vs. coolant temp). I wonder if I would need to increase "AE Max Pulse Width vs Coolant" in the same coolant range? I need to study the code more to see how the calculation is done. Sound like I'm on the right track?

Eric
 
Don't forget that one of those tables Dave mentioned is zeroed out in the stock chip so there is no AE in the stock cals. Sorry, I don't have time just now to go look up which one it is. Also, the decay times in the stock chip are very fast, at least compared to the na 3.8 cal for the 7148 ecm which does use AE, so I've always wondered what GM was thinking in our chips. Maybe they kept turning it down shorter and shorter, and then off completely (deciding they didn't need it), and left the decay stuff at the last version they tried? Just wondering out loud :).
 
Well...poop. All that thinking for nothin'. I guess I can compare it to the n/a tables and see how its activated there. I didn't see where any of the tables were set to zero. I'll keep looking.

Thanks Carl

Eric
 
Of the tables I mentioned, the only one "zeroed" is the 580-584 table.
 
The excel sheet I downloaded from GNTTYPE does not have that table zero'd out. So I looked at a stock prom image and it is zero'd. So it looks like at least deltaLV8 is never used for AE (in the stock chip), but delta TPS still is....?
 
Eric,
Keep in mind I think the spreadsheet on the web is the pre bbkj values. I think there for axca or something, can't remember exactly. Maybe that could be the difference.

Mark
87GN
 
Originally posted by TurboDave
Of the tables I mentioned, the only one "zeroed" is the 580-584 table.
Click to expand...
I'm still working from memory here but I think all the AE table lookups and decay filter get multiplied together to get the AE inj pw, so it only takes one table zeroed out to completely turn off AE. It's been a while since I went over that code and data, so Eric, please verify this.
 
It's a real catch 22 in my opinion.
You can add some AE, but it momentarily can drop the EGT and slow spooling.
Timing can play a HUGE role in this area too.
 
Originally posted by ijames

I'm still working from memory here but I think all the AE table lookups and decay filter get multiplied together to get the AE inj pw, so it only takes one table zeroed out to completely turn off AE. It's been a while since I went over that code and data, so Eric, please verify this.
Click to expand...

The one table that's zero'd is a "multiplier" table, so I don't think zeroing a "scaler/multiplier" table would turn of AE. Having no AE would make for some pretty serious "bogs" me thinks. ;)
 
Ok (keep in mind I'm an amateur at this, so I could be full of BS)

As I continue to study the 100 pages of code so kindly deciphered by Mike Pitts and Scot Sealander (gotta give em credit:)), I think I found that:

1. AE can either be activated by a change in LV8 or a change in TPS.
2. When AE based on LV8 is calculated, it is loaded into $95, which is called "additional inj. PW". The LV8 AE factor table is zero'd and therefore the additional pw is always zero. (There is even a note in text about that.) So LV8 is never used for AE.
3. When AE based on TPS change is calculated, it is loaded into $98, which is called "DFCO AE PW". It appears that the same info used for decel cutoff is also used for AE (is that right?).

I haven't even looked into decay rates yet, so I don't know how that works.

Even with the LV8 table zero'd, the resulting pw is only added on. So AE by delta TPS can still take place.

So it still appears that if someone wanted to add AE to possibly help an off-idle tip-in stumble (I know, there's also other causes of tip-in stumble) that the table "delta tps A.E. pulse width mult. vs. coolant temp" might be a place to look. Maybe the decay table, but I'm not sure yet.

This is how I spent my weekend...:rolleyes:
 
Just wanted to say it is great to hear you guys talking out loud, gives us newbies somethings to look at and think about.


Thanks
 
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