BLM Cell question...
Thread Starter
Le Mans Master
Joined: Mar 2002
Posts: 5,889
Likes: 2
From: Castro Valley Calif.
St. Jude Donor '03 thru '26
BLM Cell question...
I'm getting a 5 or 6 point jump moving from one cell to the next from time to time and I'd like to know how best to approach smoothing out the transitions. They're not exceptionally bad by any means (see attached screenshots), but they do bug me somewhat and learning new things will make me a better tuner. I can't find anything in T/P (tuning 6e, ARAP) and my thinking is to just give it a bit more timing in those particular cells because it's happy in other areas at the same GPS or RPMs. I do understand the concept of the cells using the previously stored information, but I'm just too inexperienced to know what to do about it 
Thanks for any input!
This shows up in row# 1773-1774
This one is at row# 2370-2371
Thanks for any input!
This shows up in row# 1773-1774
This one is at row# 2370-2371
Melting Slicks
Joined: Aug 2003
Posts: 3,389
Likes: 391
From: Lakeville MI
From what you've shown, cells 6, 10 and 11 are running a little lean.
It would suggest that your MAF calibration between 12-22 gm/sec and 22-34 gm/sec (assuming normal BLM cell boundaries) is a little low. Increase the MAF tables in this flow region.
It would suggest that your MAF calibration between 12-22 gm/sec and 22-34 gm/sec (assuming normal BLM cell boundaries) is a little low. Increase the MAF tables in this flow region.
Thread Starter
Le Mans Master
Joined: Mar 2002
Posts: 5,889
Likes: 2
From: Castro Valley Calif.
St. Jude Donor '03 thru '26
Thanks a lot for the response tequilaboy!!! My current boundries are 13, 21, and 34 GPS, unchanged from the ARAP bin I'm using (see screenshot below).
This is the confusing part for me though.........there are other areas in the same MAF regions (albeit different BLM Cells) that are currently showing a tad rich @ 125 BLMs (see 2nd & 3rd sceenshots below). My thinking was if I increased the MAF tables to take care of my minor lean areas in the first post, then I'd make these other areas worse because it's a global change and that's where my inexperience is showing. I wondered if I tweaked my RPM or MAF boundries a bit; or gave it a little selective timing I could smooth out the transitions a bit. I spend a good amount of time at steady cruise on the freeway and I was hoping to address that 125 BLM issue in the last screenshot below. BTW, the reported MPH is about 10-12% off because of my bigger wheels......66 MPH reported is actually closer to 73 +/-
In Town Light Cruise
Freeway Cruise
This is the confusing part for me though.........there are other areas in the same MAF regions (albeit different BLM Cells) that are currently showing a tad rich @ 125 BLMs (see 2nd & 3rd sceenshots below). My thinking was if I increased the MAF tables to take care of my minor lean areas in the first post, then I'd make these other areas worse because it's a global change and that's where my inexperience is showing. I wondered if I tweaked my RPM or MAF boundries a bit; or gave it a little selective timing I could smooth out the transitions a bit. I spend a good amount of time at steady cruise on the freeway and I was hoping to address that 125 BLM issue in the last screenshot below. BTW, the reported MPH is about 10-12% off because of my bigger wheels......66 MPH reported is actually closer to 73 +/-
In Town Light Cruise
Freeway Cruise
Melting Slicks
Joined: Aug 2003
Posts: 3,389
Likes: 391
From: Lakeville MI
Another option istead of enrichening the MAF tables below 34 gm/sec:
For bpw values below approx. 2.20 ms, you could increase the injector low pulse width offset table in order to improve linearity of the injector.
You can also tweak the O2 tables vs airflow to bias the rich lean break point in this flow region.
For bpw values below approx. 2.20 ms, you could increase the injector low pulse width offset table in order to improve linearity of the injector.
You can also tweak the O2 tables vs airflow to bias the rich lean break point in this flow region.
Thread Starter
Le Mans Master
Joined: Mar 2002
Posts: 5,889
Likes: 2
From: Castro Valley Calif.
St. Jude Donor '03 thru '26
Another option istead of enrichening the MAF tables below 34 gm/sec:
For bpw values below approx. 2.20 ms, you could increase the injector low pulse width offset table in order to improve linearity of the injector.
You can also tweak the O2 tables vs airflow to bias the rich lean break point in this flow region.
For bpw values below approx. 2.20 ms, you could increase the injector low pulse width offset table in order to improve linearity of the injector.
You can also tweak the O2 tables vs airflow to bias the rich lean break point in this flow region.
An item search on "O2" I found a table called "O2 Error Reduction Gain vs Airflow"........ The tables in this one are GPS vs multipliers of 1 or less.
An item search on "Airflow" shows a table called "Closed Loop Rich/Lean Threshold vs Airflow". These tables are GPS vs mvolt.
Like I said.............Uh-Ohhhhhhh
Le Mans Master
Joined: Feb 2005
Posts: 5,146
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From: The Motor City
When working that table I prefer to have an LM -1 going as to understand where the afr is at lower values (idle/de-cell etc.) and up 64/ish values. If tuning to that crossover point at idle for example and then achieving 128/128, that may or may not equal the desired/current afr of 14.4. The same applies to the stock gm/area @64 gm. 535 (arap stock numbers), This may or may not equal a desired afr when tuning (also applies toward AE and all higher load values ramping toward a lower afr).
Another method that I use is to first correct all of those while keeping the load range around 60 or so (in your scans you're close to the lv/ae load transition. After getting those in line, then when at the same gm/sec. at higher load/lv (90 should be the next value) tweak the lv ae slightly to keep it under control.
Last edited by mseven; May 30, 2011 at 09:01 AM.
Thread Starter
Le Mans Master
Joined: Mar 2002
Posts: 5,889
Likes: 2
From: Castro Valley Calif.
St. Jude Donor '03 thru '26
Thanks Mick, this gives me some homework to do. tequilaboy, I was just getting ready to bring up the Closed Loop Lean vs Airflow and boom.........the FP Regulator Diaphram let go during a cruise
Joy...........the superram plenum has to come off & I'll need to figure out where I was to re-acquire the tune I had; or tweak it back again.
There is so much to learn, but it's fun stuff for sure
Joy...........the superram plenum has to come off & I'll need to figure out where I was to re-acquire the tune I had; or tweak it back again.
There is so much to learn, but it's fun stuff for sure
