PCM Diagnostics & Tuning HP Tuners | Holley | Diablo

Clairification on Throttle Cracker and follower

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Old Sep 14, 2006 | 02:02 PM
  #21  
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I would tune for SD then I would connect my MAF for a while, then when I would go back to SD, I noticed my VE was way off, even if it was similar weather and conditions. I suspect the VE correction to be the culprit.
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Old Sep 14, 2006 | 02:11 PM
  #22  
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Hmmm....must be an HPT thing. I have yet to see anything like that in EFI Live.
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Old Sep 14, 2006 | 02:14 PM
  #23  
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Originally Posted by SSpdDmon
Hmmm....must be an HPT thing. I have yet to see anything like that in EFI Live.
Weather or not you can see the tables, the stock PCM does indeed have them. It wouldnt be an HPT vs EFI Live thing.

Dont get me wrong, if you get everything dialed in correctly it wont be a problem, however it did see like it could complicate the tuning process, so i decided to effectively disable it.
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Old Sep 14, 2006 | 03:34 PM
  #24  
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I am talking about the "VE Correction Factor Filter
Coefficent", not the correction factor itself. From the
description this appears to be a smoothing function
-on- the correction which would slow the thing down.
Attached Thumbnails Clairification on Throttle Cracker and follower-ve_filt.jpg  
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Old Sep 14, 2006 | 03:46 PM
  #25  
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Originally Posted by jimmyblue
I am talking about the "VE Correction Factor Filter
Coefficent", not the correction factor itself. From the
description this appears to be a smoothing function
-on- the correction which would slow the thing down.
Im talking about the entire rightmost column. VE correction as a whole. Its simply a mechanism to let dynamic airflow auto-learn to fall inline with steady state MAF. I dont believe it has anything to do with transients. The field youre pointing to would dictate the VE correction learning process, which AFAIK does not smooth or otherwise change airflow or fueling on a transient.
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Old Sep 15, 2006 | 09:18 PM
  #26  
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VE Correction Factor
The VE Correction Factor is used to maintain a relative offset between the VE calculated airmass and the MAF measured airmass to ensure smooth transition between steady state and unsteady state behavior. To protect against unstable behavior the VE correction factor has limits in place and a reset condition.

What defines "steady state" and "unsteady", in laymans terms?
If your in speed density wouldnt this be a moot point since the maf is disabled?
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Old Sep 16, 2006 | 02:06 PM
  #27  
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Originally Posted by 02sierraz71_5.3
VE Correction Factor
The VE Correction Factor is used to maintain a relative offset between the VE calculated airmass and the MAF measured airmass to ensure smooth transition between steady state and unsteady state behavior. To protect against unstable behavior the VE correction factor has limits in place and a reset condition.

What defines "steady state" and "unsteady", in laymans terms?
If your in speed density wouldnt this be a moot point since the maf is disabled?
I am interested in this as well as I have the lean spike condition when I nail the gas from a roll. The first cell that I hit at WOT in my VE table is always lean (stoich). It's like the PCM hesitates for a second before comanding PE. I have even tried changing my OLFA tables to command the 12.7:1'ish AFR that I want to see in the 90-105 KPA cells. I am running OLSD.

As mentioend above, I was operating under the assumption that the dynamic airflow stuff was all MAF related.
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Old Sep 16, 2006 | 03:30 PM
  #28  
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There are a couple of delta-MAP values that define the
"steady" condition. Lo MAP Delta and Hi MAP Delta, in
Engine>Airflow>Dynamic Airflow in HPTuners' setup.
There is also a delta TPS pair.

Dynamic Airflow is the rollup of all sensor inputs and all
smoothing / filtering / prediction, the final value being
used to compute fueling. Depending on operating point
it may resemble more the MAF or the SD, a blend or
something loosely based on recent events. I believe
in a SD vehicle all that happens is, the MAF is no longer
considered as a Dynamic Airflow contributor but
everything still runs through the same sausage grinder.
Just no more hog snout in the mix.
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Old Sep 17, 2006 | 09:10 AM
  #29  
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I would love an explanation on what changes what in the steady state section. I.e. raising this value does this and lowering that value does that. I'm not good enough at this stuff yet to care about all of the theory and understand how it works. I just want to understand how changes (+ or -) to the values effect the tune. Thanks in advance.
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Old Sep 17, 2006 | 12:27 PM
  #30  
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Originally Posted by 98Z28CobraKiller
I am interested in this as well as I have the lean spike condition when I nail the gas from a roll. The first cell that I hit at WOT in my VE table is always lean (stoich). It's like the PCM hesitates for a second before comanding PE. I have even tried changing my OLFA tables to command the 12.7:1'ish AFR that I want to see in the 90-105 KPA cells. I am running OLSD.

As mentioend above, I was operating under the assumption that the dynamic airflow stuff was all MAF related.
This helps with that
Originally Posted by 02sierraz71_5.3
the easiest fix Ive found for this is to set the PE to engage lower meaning drop the TPS to 40% from 3000 rpms and up, then set the enrichment rate to 4.0, and drop the map enable to 45 this ensure you get your fuel when you need it.
Then tweak the PE divisor quick and easy.
Youd be suprised how much of a difference this makes especially with motors that move alot of air.

Obviously if your having to set your pe divisor to 2.0 to command 13:1 afr or something rediculously high then you know your ve table is very lean and you need a SD tune to fix the VE table.
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