LOW "Block Learn" Values?? What's the cause??

[gmrulz4u]

I have a 1989 Olds Cutlass Supreme 2.8L. The other day, I received my new AutoXray(as you all probably already know via my previous posts:)). I've been monitoring my "Block Learn" lately, and noticed that it's pretty low. I understand it's supposed to be as close to 128 as possible. While driving, my "Block Learn" is almost ALWAYS between 108-115. This, I believe, indicates that my engine is running "rich". Also, the "BLK LRN Cell" is always either 0, 1 or 2(however I don't really know what this actually mean!).

 

So my question is what could possibly cause a LOW "Block Learn" value?? I've always had suspicions that my car ran RICH, and now I can confirm it.

 

I will let you know that I use 91 Octane Shell Optimax(Super Clean) Gasoline, just incase this could be a cause??

 

THANKS EVERYONE!

[msvestka]

I have a 1989 Olds Cutlass Supreme 2.8L. The other day, I received my new AutoXray(as you all probably already know via my previous posts:)). I've been monitoring my "Block Learn" lately, and noticed that it's pretty low. I understand it's supposed to be as close to 128 as possible. While driving, my "Block Learn" is almost ALWAYS between 108-115. This, I believe, indicates that my engine is running "rich". Also, the "BLK LRN Cell" is always either 0, 1 or 2(however I don't really know what this actually mean!).

 

So my question is what could possibly cause a LOW "Block Learn" value?? I've always had suspicions that my car ran RICH, and now I can confirm it.

 

I will let you know that I use 91 Octane Shell Optimax(Super Clean) Gasoline, just incase this could be a cause??

 

THANKS EVERYONE!

 

There are really two parameters of interest when talking about fuel corrections; LTM and INT. The Long Term Memory (LTM) is a correction your car's ECM learns to correct the fuel delivery for your particular vehicle. A LTM in the 108-115 is nothing to be alarmed about. You could think of the LTM as a old response correction term. The INT is a quick response correction term to the fueling based on O2 sensor readings. This one should always find it's way back to 128.

 

In a nutshell what your car's ECM does is calculates the air coming into the engine by reading the MAP, RPM, and IAT multiplies this by your F/A ration (1 / 14.7) multiplies this by LTM/128 and INT/128 this gives your the quanity of fuel you want to deliver. It then converts this into injector pulse width. Once the fuel is delivered, it looks at the O2 sensor to see if how close it was, it then adjusts the INT accordingly.

 

So a LTM or INT less than 128 are pulling a little fuel away to keep the A/F ratio at stioch and INT / LTM above 128 are doing adding fuel to keep the engine running at stioch.

 

LTM's above or below 128 are not an indication that your engine is running rich or lean. All the LTM is telling you is the correction that has being applied to keep your engine running at stioch from the nominal engine.

 

Hope this helps,

Michael