BLMs 108-120 Question
Thread Starter
Safety Car
Joined: May 1999
Posts: 3,651
Likes: 5
From: Atlantis
Cruise-In I Veteran
BLMs 108-120 Question
My BLMs are running from a low (as it can go :) ) 108 to a high of 120 at all KPA before PE.
I don't have an AFPR installed and don't really want to reduce FP anyway.
Since this seems to be an across the board change I don't want to adjust the VE table.
Is there something I can do with the Injector Constant that will bring the BLMs closer in line that won't mess up WOT mixture?
How can I tell without a WB what effect any change may be having on WOT mixture?
I DON"T WANT TO CROSS 128 to the "DARK SIDE". (lean)
BTW: BLM is constant at 108 during idle.
Idles a 'little' rough (not much) and runs GREAT
Advice, opinions, guesses? ALL welcome.
Mods:
K&N and Open Lid
TB Bypass
AIRFOIL .... I know
ADS SuperChip
[Modified by VetNutJim, 5:53 PM 6/4/2003]
I don't have an AFPR installed and don't really want to reduce FP anyway.
Since this seems to be an across the board change I don't want to adjust the VE table.
Is there something I can do with the Injector Constant that will bring the BLMs closer in line that won't mess up WOT mixture?
How can I tell without a WB what effect any change may be having on WOT mixture?
I DON"T WANT TO CROSS 128 to the "DARK SIDE". (lean)
BTW: BLM is constant at 108 during idle.
Idles a 'little' rough (not much) and runs GREAT
Advice, opinions, guesses? ALL welcome.
Mods:
K&N and Open Lid
TB Bypass
AIRFOIL .... I know
ADS SuperChip
[Modified by VetNutJim, 5:53 PM 6/4/2003]
Thread Starter
Safety Car
Joined: May 1999
Posts: 3,651
Likes: 5
From: Atlantis
Cruise-In I Veteran
Re: BLMs 108-120 Question (ZD1)
128 is the 'preferred' value.
It means the ECM is not having to correct the mixture by adding or substracting fuel. Not having to bounce around in the cells means the mixture can be maintained to the 'preferred' value faster.
The Integrater won't have to be taking cell values and applying corrections in the ECM and the engine will run 'better'.
Disclaimer: YMMV on the explanation....I've never been too good at teaching.
It means the ECM is not having to correct the mixture by adding or substracting fuel. Not having to bounce around in the cells means the mixture can be maintained to the 'preferred' value faster.
The Integrater won't have to be taking cell values and applying corrections in the ECM and the engine will run 'better'.
Disclaimer: YMMV on the explanation....I've never been too good at teaching.
Former Vendor
Joined: Jun 2001
Posts: 7,204
Likes: 6
From: St Marys PA
Re: BLMs 108-120 Question (VetNutJim)
I for a MAP system, I'm assuming you have since you said VE tables. I would set the injector constant to the exact size the injectors are, then start to tune the VE tables. To correct blms. This is where SD does have its destinct advantage.
There is also a VE master program that will calculate your prefered VE tables for you, after some data imput. You have to make several atempts to get it all dialed in, but after a few it will hone right in on the correct values. Pretty slick. I have never used it first hand, but hear its does alot of the work for you.
Even it you go to 140s or even 160s you fine as far as AFR at cruise. That just means the car is adding fuel, instead of your 108 blm and its subtracting fuel. In either case your still at 14.7 AFR.....so don't be alarmed that your 128+.
Just take it slow and easy and make note of changes and you will be OK. If you get it 128 +/- 3-4 blms that is pretty decent and you most likely won't tell the difference between 133 and 128, but you will notice a huge difference in throttle resonse between 108 and 124 thru 133. :eek: :cheers:
There is also a VE master program that will calculate your prefered VE tables for you, after some data imput. You have to make several atempts to get it all dialed in, but after a few it will hone right in on the correct values. Pretty slick. I have never used it first hand, but hear its does alot of the work for you.
Even it you go to 140s or even 160s you fine as far as AFR at cruise. That just means the car is adding fuel, instead of your 108 blm and its subtracting fuel. In either case your still at 14.7 AFR.....so don't be alarmed that your 128+.
Just take it slow and easy and make note of changes and you will be OK. If you get it 128 +/- 3-4 blms that is pretty decent and you most likely won't tell the difference between 133 and 128, but you will notice a huge difference in throttle resonse between 108 and 124 thru 133. :eek: :cheers:
Drifting
Joined: Mar 2001
Posts: 1,636
Likes: 3
From: Lafayette IN
Re: BLMs 108-120 Question (VetNutJim)
Jim,
Are those the only mods you have at all, or have you swapped in a different set of injectors/pressure regulator?
I wouldn't expect to see that much of a difference with your BLMs from those mods listed.
What scan tool are you using and what BIN are you using? If the scntool has the ability to export into a DBF or other Excel file, I can run the data and see what I come up with. Email em to me with the addy in my profile.
Thanks, -Matt
Are those the only mods you have at all, or have you swapped in a different set of injectors/pressure regulator?
I wouldn't expect to see that much of a difference with your BLMs from those mods listed.
What scan tool are you using and what BIN are you using? If the scntool has the ability to export into a DBF or other Excel file, I can run the data and see what I come up with. Email em to me with the addy in my profile.
Thanks, -Matt
Thread Starter
Safety Car
Joined: May 1999
Posts: 3,651
Likes: 5
From: Atlantis
Cruise-In I Veteran
Re: BLMs 108-120 Question (VetNutJim)
Hey guys,
I was just wondering. Could a old O2 sensor cause this?
Would low output from the 02 sensor cause BLMs to be low or high?
This one is probably the original one with 103,000 miles on it.
I picked up a new one on the way home this afternoon.
But I don't want to change it unless I really need to.
I was just wondering. Could a old O2 sensor cause this?
Would low output from the 02 sensor cause BLMs to be low or high?
This one is probably the original one with 103,000 miles on it.
I picked up a new one on the way home this afternoon.
But I don't want to change it unless I really need to.
Thread Starter
Safety Car
Joined: May 1999
Posts: 3,651
Likes: 5
From: Atlantis
Cruise-In I Veteran
Re: BLMs 108-120 Question (ski_dwn_it)
Hey Ski,
Was that a 'yes' that the 02 could be causing my BLMs to be funky?
Well.....here's what I did...... I was too lazy to change the 02....yet.
I reprogrammed the lower and upper VE tables.
Took my lowest reading.... (108) and my highest reading (120)
and averaged them (108+120)/2 = 114.
Divided 114 by 128 (114/128) = .890625. (rounded to .89)
Used that as a scaler for all the VE table number from 600 rpm on up.
The idle BLM is now 120 instead of 108 but becuse of rain, I haven't had a chance to do a data log run.
BTW: I cut and pasted the VE table values into a spreadsheet and applied my scaled value to the 'modified' rows.
(I stored the original VE values in the spreadsheet also so I can see at a glance what I started with)
Then I cut and pasted them back into the VE table.
Using a calculator and modifying them one at a time was taking toooooo long.
Any guesses on what the results will be when I get to drive it?
Was that a 'yes' that the 02 could be causing my BLMs to be funky?
Well.....here's what I did...... I was too lazy to change the 02....yet.
I reprogrammed the lower and upper VE tables.
Took my lowest reading.... (108) and my highest reading (120)
and averaged them (108+120)/2 = 114.
Divided 114 by 128 (114/128) = .890625. (rounded to .89)
Used that as a scaler for all the VE table number from 600 rpm on up.
The idle BLM is now 120 instead of 108 but becuse of rain, I haven't had a chance to do a data log run.
BTW: I cut and pasted the VE table values into a spreadsheet and applied my scaled value to the 'modified' rows.
(I stored the original VE values in the spreadsheet also so I can see at a glance what I started with)
Then I cut and pasted them back into the VE table.
Using a calculator and modifying them one at a time was taking toooooo long.
Any guesses on what the results will be when I get to drive it?
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
