To lean out the mixture at a given point do you increse the number or decrease it? is this best done in an ascending manner or can a single point be adjusted to work? ( I have Tuner Cat)

My part throttle BLMs are in the 130s I thought I'd adjust it a touch to see what happens but not sure which direction to take the numbers. The O2s at this same time read high 800s (flash at times to 300 but for a milisec)

 

The MAF numbers are a measure of air flow. Decreasing the numbers tells the computer less air so less fuel is added. Basically, lowing the numbers leans the car out. Change the numbers by % so you keep whatever function or slope the computer is using in that range. You will see changes in BLMs using as little as 5% decrease so don't go crazy. Naturally a 5% change is alot more when adjusting MAF in the lower ranges than the higher so keep that in mind also.

BTW; this is how I did most of my part throttle tuning and my car almost sounds stock now. As far as cam choppyness, I mean. That maybe a bad thing for some people though. I sort of miss the rougher idle I had but my gas mileage is way better now. I did have blms in the 140s though.

Have fun playing with it. It's a slow process. The only way to get results is to change ONE small range were you notice high blms and drive the car for at least a few hours and take a log. That was the only way that worked for me. When I started, I was chasing myself by making to many changes too fast and I just ended up starting over.

JD.

 

Maybe this will help:

A BLM in the range of 134 to 135 is having the ECM(PCM) adding about 5% more fuel. The ECM calculates a specific PW (pusle width) for the injectors, the O2 sensor gives feedback that the PW caused a slight lean condition, so the BLMs will move from 128 (perfect stoic) to a larger number, for example 135. With the calculated PW value and the BLM correction value (INT comes in here also) gets you to stoic during part throotle driving.

What you want to do is to force the calculated value for PW to be 5% larger.
This will force the BLM value to go down. There are two ways that I have used to correct the BLM to be closer to 128 when you are at 135. 1) increase the MAF table by 5% (if you have an entry of 100, it will become 105). If the ECM sees more air coming in, it will calculate a larger PW. 2) Decrease the fuel injector constant by 5%. If the ECM thinks its got smaller injectors, the ECM will respond by calculating larger values for PW.

 

Put the thing on a dyno and use this file to tune it WOT, it only took me one dyno run 5hp stock, and my buddies LE2 7rwhp with only one dyno pull. Then you plug in your A/F, then you plug in your desired A/F and thats it, all the math is done for you. What you are trying to do is trick the computer into doing something, because you dont know what to change. This will help with your WOT.

www.texasfbody.com

 

Sorry it tookme so long to get back to this (home with the sick kids)
But your answers are exactly what I was looking for, thanks guys !!!

 

You're the heat man. Thank you for the site.

 

i will be puting alot more on that site in the next couple of days.