I am not looking to mod anything just trying to figure how one table is related or effected by others.

Looking at the MAF tables in Tunercat, I see the MAF measurement as gm/sec and how whatever the sensor detects correlates to a certain frequency. What do the signals effect though? I assume air/fuel ratio but do not see another table that relates to the MAF tables. Anyone care to explain it for me please?

Jeff D.

 

the maf sensor measures frequency and then uses the table to relate an air flow value to that frequency

 

What the algorithim? or is that even known?
I can see that it's sort of not relavent to programming a pcm for a cam or whatever because it appears to be intergraded into an algorithim. Most likely the one for the base injector pulsewidth which is part of final pulsewidth calc. I don't know. Just looking into programming alittle more. Thanks for the reply.

Jeff D.

 

The MAF is part of the closed loop system that is governed by the 02 sensors. The frequencies and how they relate to air flow is coded into the PCM, hence why we can change them.

Ultimately, the 02's rule. If too much or too little air, (as shown by the MAF) the computer modifies the BLM's to give it correct AFR (non PE mode only). These 02's also allow us to calibrate the MAF so that the computer does not have to "work" at correcting. This is most important when PE mode is enabled.

02's read exhaust and if a different cam is installed, overlap changes allow for different readings than what would have normally been shown. This will not change you MAF readings but it will make the computer compensate for this new condition by the only way it can: fuel. That is when calibration is done to the MAF.

Hope this helps.

Ben

 

This sounds like PE mode operates in closed loop. Must be thinking something else. You mean the PE values will be closer when it does go to them? I thought the BLM locked at 128 in PE mode unless your BLM value was higher than that going into it; which it then used that higher value instead.

Jeff D.

 

What I and others have confirmed is our computers use the last BLM within the cell when the car goes into PE mode. Knowing this, we do not want our fuel needs to fluctuate within the cell while PE is enabled (unless of course you have wideband tested and modified your PE tables to accomodate). This can lead to improper fueling and thus a lean condition.

 

I didnt think this is true, the car will never go lean because it will never start in PE mode with a BLM lower than 128. Did you read my other post explaining this Man, we must be thinking way different.

Jeff D.

 

AFAIK, the MAF is never ignored. IOW, PE mode is not = speed-density. PE mode does ignore the O2 sensors though, so it follows an "open loop" algorithm, which is an entirely different animal than speed-density. When the MAF maxes (which has nothing directly to do with PE mode) the inputs for calculating pulse width are the MAF output (which is at a constant max value), MAP, and RPM. Not sure what role TPS plays in these conditions, so it's kind of a speed-density mode.

Rich Krause

 

http://web.camaross.com/forums/showt...&highlight=WOT

Hopefully this post explains what I mean.

Ben

 

this is not true...

the last blm seen by the pcm is incorprated in to the final A/F ratio that the pcm uses for PEmode. my buddy car was programed by a individual (no names) and the individual program the blms a 122. i dont why but this was the problem. the car ran real rich at WOT and i counldnt lean it out. so i went into the maf table corrected the blms and have had no more trouble.

i thnk this is the formula (last seen blm/128) + (plus the A/F ratio desidered in the pemode)

so if you had a set A/f ratio you wanted say 13.0 (in pe mode) and the last blm the pcm saw was 150. that means the pcm is seeing lean and is adding fuel.

the car will go into pemode with blms under 128.