PE tuning procedures/questions....

[BlackGMC]

I have my part throttle dialed in pretty good, now I am looking at dialing my WOT/PE part. Since I have not seen any real procedures/quides I have kinda pieced together my plan of attack. From my understanding fueling below "RPM Threshold for Airflow Calculation" (B0120) (4000 default), the computer uses a combination of VE and MAF to calculate the amount of air needed to achieve the AFR Commanded. Above that value the computer uses MAF only to achieve the AFR Commanded. Is this correct? I am sure there are a few other modifier tables that will affect the AFR, but from what I have read these are the main ones....

1. I am starting with a mild spark advance so that should not be a problem.
2. Adjust tune for OLSD in order to tune the VE table. I will be filtering/excluding all TP% < 95, this way I only get WOT values.
3. I have set my PE table (B3618) up like the below picture. From my understanding once the PE enablers have been met the computer will take the richer of the two tables (Commanded Open Loop (B3605) and PE (B3618)). I have read that is good to richen up the mixture at peak TQ and leaner at peak HP. From the dyno graphs I have seen on stock interal 4.8s peak TQ is ~4500-4800 and peak HP is ~5900-6000.

4. I will use a BEN correction based off of my WB to align the VE table in the MAP ranges 90-100. This should take care of the <4000 rpm range which from my understand is where the VE table comes into play. Above that is strictly MAF.
5. Next I will re-enable the MAF and lower the "RPM threshold for Airflow Calculation" (B0120) to roughly 1500-2000 RPM to dial in the MAF table.
6. I will use the BEN correction based off of my BW to align the MAF Table (B5001). Filtering/excluding all TP% < 90..
7. after all that then put tune back to CL mode....

So does this sound like a good way to tune WOT fueling??? Eventually I will do this same procedure at the track to adjust the different AFR values to obtain the best AFR for my truck, but until then this is what I am starting with....

Anyone see any problems with any of that?

[cmitchell17]

My table is a lot more flat. It used to almost be like yours, but after I started to think if your supposed to richen it at peak torque it would be a lot smoother as torque dosent just go up a lot at 4000rpms.

How much of an influence does the maf have on fueling under 4000rpms.

I had a air intake tube I bought(after rats chewed through mine), but traded it to a friend with a 2500LQ4, and put his stock one on. I fiquered the wierd looking chambers did something to help the maf read air. So does the maf give a accurate reading at below 4000 rpm WOT?

Sorry I couldnt answer your question blackgmc, and just asked one of my own.

[joecar]

Probably make 4400 the same as 4800, and smoothen from 2800 to 4400... like Cmitchell said, torque doesn't just appear at that RPM.

MAF may still have a significant effect below 4000... even if PCM uses a combination of MAF and VE.

The MAF is not as simple as it looks... the air mass flowing past it behaves similar to DC + AC (or a waveguide with standing wave resonance... yes, I'm an EE ), and the air tube may have significant effect on this, as does the screen on some MAF's.

Some MAF's may be consistent everywhere, others may wander around everywhere... even MAF's on different instances of the same vehicle model.

[BlackGMC]

That graph was mainly derived from threads I have seen on here and HPTuners. I got a PM from a another tuner advising me to richen up the mixture more and basically make is smoother.

[redhardsupra]

the only way to get your target AFR right is to use a real dyno to determine the optimal AFR and timing. if your VE and few other tables are set up perfect, then you just set up your PE to whatever EQ ratio you got through the on-dyno experimentation and you're done.