Calc.VET: correcting MAF and calculating VE (in single log)

[rpmauto]

Take a look at this log and let me know what you think. Selbens are perfect, wot air fuel averages out to be perfect. But I dont understand the variance i have between banks on trims. One time I will look over when I am driving and bank one is at positive 5 and bank 2 is -2%. I dont have any exhaust leaks. It didnt do this till I put the new o2 sensors in. If you look at the average for the log it all looks good, but if you pick parts of it apart it looks funky. Maybe I shouldnt worry about it so much. I do now though I see have a .8 fuel trim at wot that I didnt have before. I assume I should tweak the maf table to take care of that.

Anyway let me know what you think and if you would do anything further, as far as getting the trims in line.

[WeathermanShawn]

Well I guess you could drop SAE.SPARKADV and perhaps VSS Pid and log both GM.HO2S11 & GM.HO2S21.

I don't know if just matching different O2's would be the culprit. I guess you could always switch the O2's (banks) and see if the annoying imbalance follows.

I agree it would drive me crazy too.

I don't think it is anything in the Tune that is the culprit..

[joecar]

Good log

Also log GM.DYNAIR [g/s]... drop IAT and ECT if necessary.

MAF signal starts oscilliating (or something) above 4000 rpm, the oscillations look big... that has me a little concerned.

[rpmauto]

Joe, I see the oscillations of the maf hz. I looked back at some of last years logs and those look good. Some oscillation, but not much. That is kinda concerning. The maf is a delco 85 mm z06 unit, so it doesnt have a screen. I wonder if that is why the airflow at higher rpm isnt smooth. I will try and get a log between raindrops today. I dropped vss, spark, kr. I have 25 pids and 21 channels selected.

What exactly is GM.DYNAIR, the pcms calculation of expected air vs. other conditions?

Also, what rates are your scantool set up at. Mine seems slower. I see the variance, but it isnt as bad on my log.

[joecar]

GM.DYNAIR is airflow [g/s] based on VE.

I want to compare MAF to DYNAIR.

We also want to compare CYLAIR_DMA (MAF based) to DYNCYLAIR_DMA (VE based), you're already logging these.

See post #2 here: showthread.php?14188-Summary-Notes


With Logging Scan Mode set to Stream Fast, the logging rate should be 10 updates/second with 24 or less pid channels (i.e. about 0.1 second between each sample point).

[rpmauto]

Got a good log in tonite. Before the log I swapped in two more brand new a/c delco afs123 o2 sensors. And made a change to the hood opening on the car to see if that would maybe have some effect on the unstable maf at upper rpms. Log looks really good. o2s are switching good. Trims look great (other than at idle, that needs some more ve, or maf table work now I think) And it looks like the major oscillation in the maf is gone. There is still some, but at least on my scantool it looks better. I logged the pids that Joecar said to for comparison. Take a look at it and let me know what you think.

[WeathermanShawn]

Wow, Len you have some of the best logs.

You have nailed the Trims and your fueling looks close to perfect in PE Mode and WOT.

Maybe changing both O2 sensors at the same time helped equalize the banks.

To me your MAF Freq still looks like there is some turbulence, but then I don't normally ever hit 13,000 on the MAF Frequency...Even though it oscillates to some degree it looks like you still maintain the same EQ/AFR during your WOT runs.

As far as tune-wise, you have nailed another one.

Good job!

[rpmauto]

Thank you Shawn, living in a rural area really helps with getting good logs for wot stuff. I am very pleased with the tune. Now I can address the slight surge and some other things.

I do still have to get my idle trims in line, last log they were as high as +11. I didnt log spark, so unless i change the filter I cant use the data from last nite. But as far as idle goes, is it better to adjust the maf table, or the ve table to get your trims in line. I think the ve table is pretty close as it hasnt changed much in the last several logs, so I am leaning to the maf table for getting the idle trims back in line.

[WeathermanShawn]

Len, my Idle theories are that on a MAF-Enabled vehicle, it is still primarily the MAF that affects Idle Trims such as LTFT's. You see the VE Table's influence primarily on cold-open loop start-up.

It gets tricky manipulating the MAF Frequency for Idle, because sometimes the same airflow is present at 0% TPS or low load. So just do the best you can.

The tight CALC.VET filter that has Spark in it, is to try to filter out DFCO transitions. Lately, I have just been trying to suggest Tuners disable DFCO as I have seen better results that way. You can still use the other tight parameters and just drop spark.

Thanks for all your logs. You have helped show that 100% WOT is the best way to dial in PE Mode..like you said not as easy to do if you live in an urban area...

[s10mods]

I followed the CALC.VET pdf, I set up everything and ran a log, applied filters, but when I copy the values fromt the CALC.VET map, the values are low (1.3-2.5) and my VE values are high, 70's and 80's. so when I copy and paste it makes my VE talbe all screwed up, am I pasting wrong? I did a copy with labels and a paste with labels.