How to get BLM in order?
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From: Indiana, PA
Car: 86 IROC
Engine: SC'ed 350
Transmission: 700R4
Axle/Gears: 4.11 12bolt
How to get BLM in order?
I have studied some ALDL data from my car and have noticed my BLM ranges from 112 to 118 between idle and 2800 rpms. If I have read hundreds of posts correctly this should mean that it's running rich? I guess this could explain why my bumper has black spots on it where the exhaust pipes exit.
So my prom writer/eq is on the way, how do I get my BLM in order?
I have searched/read hundreds of posts on this site and I'm getting two ways to do this. Via the MAF tables or the BPW vs Load table. So which is it?
Everyone makes it sound like there is a step by step very detailed tutorial on the subject but I can't seem to find any.
So my prom writer/eq is on the way, how do I get my BLM in order?
I have searched/read hundreds of posts on this site and I'm getting two ways to do this. Via the MAF tables or the BPW vs Load table. So which is it?
Everyone makes it sound like there is a step by step very detailed tutorial on the subject but I can't seem to find any.
Supreme Member
Joined: Jan 2003
Posts: 4,620
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What you can do is to drive at a particular RPM and manifold pressure, taking note of the BLM at that operating condition.
Let's say it's 115.
Divide 128 by that number (if that number was higher than 128, you would divide that number by 128 instead).
128/115 = 1.11
Then, go to your VE table and find the RPM and MAP you were at. Let's say it was 56.
Simply multiply multiply 56 by 1.11
56 * 1.11 = 62
Plug 62 back into that cell.
Do this for several different operating conditions. You can then kind of "blend in" the adjacent cells a little to smooth it out. A few iterations with this method should get you really close.
Let's say it's 115.
Divide 128 by that number (if that number was higher than 128, you would divide that number by 128 instead).
128/115 = 1.11
Then, go to your VE table and find the RPM and MAP you were at. Let's say it was 56.
Simply multiply multiply 56 by 1.11
56 * 1.11 = 62
Plug 62 back into that cell.
Do this for several different operating conditions. You can then kind of "blend in" the adjacent cells a little to smooth it out. A few iterations with this method should get you really close.
Senior Member
Joined: Oct 2001
Posts: 571
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From: Starkville, MS
Car: 1991 Camaro Z28
Engine: 350
Transmission: 700R4
Originally posted by ULTM8Z
What you can do is to drive at a particular RPM and manifold pressure, taking note of the BLM at that operating condition.
Let's say it's 115.
Divide 128 by that number (if that number was higher than 128, you would divide that number by 128 instead).
128/115 = 1.11
Then, go to your table VE table and find the RPM and MAP you were at. Let's say it was 56.
Simply multiply multiply 56 by 1.11
56 * 1.11 = 62
Plug 62 back into that cell.
Do this for several different operating conditions. You can then kind of "blend in" the adjacent cells a little to smooth it out. A few iterations with this method should get you really close.
What you can do is to drive at a particular RPM and manifold pressure, taking note of the BLM at that operating condition.
Let's say it's 115.
Divide 128 by that number (if that number was higher than 128, you would divide that number by 128 instead).
128/115 = 1.11
Then, go to your table VE table and find the RPM and MAP you were at. Let's say it was 56.
Simply multiply multiply 56 by 1.11
56 * 1.11 = 62
Plug 62 back into that cell.
Do this for several different operating conditions. You can then kind of "blend in" the adjacent cells a little to smooth it out. A few iterations with this method should get you really close.
You'd put 115/128 ~ 0.9
Then multiply that factor against the value in the table to get the new value (VE for SD, Fuel BPW for MAF) value. Now the computer would add less fuel for that cell.
wwnf...This is correct for SD cars I'm not sure if it works the same way for MAF ones.
You might want to check this post out if you have not...
https://www.thirdgen.org/techbb2/sho...hreadid=133967
It seems to suggest that you apply the correction factor BLM/128=Correction Factor and manipulate the BPW Fuel vs Load (the second table) FYI I have a SD car so realize I've NEVER tuned a MAF car so you may want to wait for another reply.
Check this one it's short and Traxion gets right to the point.
https://www.thirdgen.org/techbb2/sho...light=MAF+tune
Last edited by Black 91 Z28; Jun 22, 2004 at 03:04 PM.
Thread Starter
Member
iTrader: (1)
Joined: Mar 2002
Posts: 198
Likes: 1
From: Indiana, PA
Car: 86 IROC
Engine: SC'ed 350
Transmission: 700R4
Axle/Gears: 4.11 12bolt
So for example if I'm using $32 and I have BLM of 112 at idle and my ALDL data is saying that my MAF is 5.15 - 5.28. I should go into my MAF tables and look where these readings would be pulled from and lower the values slightly so less fuel is added right?
Junior Member
Joined: Mar 2003
Posts: 28
Likes: 0
From: Chicago
Car: 89 IROC
Engine: 350 TPI
Transmission: Auto
I got ~128 BLM's via the MAF tables.
Here is a thread I posted that details exactly what I did:
https://www.thirdgen.org/techbb2/sho...hreadid=238467
If your running rich at all rpms, you may want to check/tune the fuel pressure first, verify your injector constant, and make sure your injectors are all working properly(not leaking or anything).
Here is a thread I posted that details exactly what I did:
https://www.thirdgen.org/techbb2/sho...hreadid=238467
If your running rich at all rpms, you may want to check/tune the fuel pressure first, verify your injector constant, and make sure your injectors are all working properly(not leaking or anything).
Last edited by Gomer; Jun 22, 2004 at 04:05 PM.
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