Read a bunch, keeping the MAF (even though calibration sux).

I have some questions about different techniques that I've read about. What's the "best" way to do it without a wideband?

First, get VE table correct. Got it.


Now, here are three methods I've read about.....

Method 1: (from HPT help section in scanner)
Dialing in the MAF

To re-enable the MAF simply plug it back in (if you previously unplugged it) and set your MAF Fail requency back to its original value and write it to the vehicle.
Load the MAF - AFR Error.hst histogram.
Make sure you log MAF in Hz in the table and go for a drive.
Hit as many of the higher frequency cells as possible as many times as possible
Copy & paste special-multiply % to your MAF airflow vs. frequency table & smooth
Save & load new calibration
Repeat if necessary
Again the cells in the histogram should get closer & closer to 0% indicating 0% difference between actual AFR and commanded AFR.

Method 2:
Hook up MAF, but DISABLE it (set fail frequency to zero).
Log Dynamic airflow and MAF frequency (Hz)
Export data to excel and average dynamic airflow (metric) for each frequency.

Method 3:
Hook up MAF, ENABLE it.
Log MAF frequency and LTFTs. (histogram)
Increase/Decrease MAF table by percentage that LTFTs are off compared to LTFTs with MAF disabled (i.e. I aim for -2 with my VE table, so aim for -2 with MAF enabled).

Summary:
Method 1: MAF enabled, MAF airflow vs. Dynamic airflow error percentage (I think)

Method 2: MAF disabled, replace MAF table with straight Dynamic airflow averages.

Method 3: MAF enabled, use LTFTs to calculate MAF error.

Confused anyone? Me too.

 

Method 1

 

method 1...basically you dial in your ve table then do basically the same thing once the maf is functional again...just dial that in so both are spot on.

 

www.allmod.net/hpt

the granddady of them all, still works fine, even tho histos do make it easier.

 

Isn't that basically method 2? I've read so much stuff, it all kinda blends together. But, I'm pretty sure I got the method 2 from you.

What I'm trying to find out is what way, in theory, is best and why.

Like, MAF on or off for calibrating. To use LTFTs to calibrate, it obviously has to be on. But, does having the MAF on affect MAF airflow or Dynamic airflow, or are those just calculations that the MAF doesn't affect?

And, should the MAF be changed based on the diffference between MAF airflow and dynamic, or should the MAF numbers just be replaced by the dynamic numbers (or is that basically the same thing)?

In theory, when the MAF is calibrated correctly, should the LTFTs look basically the same with the MAF hooked up as with it unhooked?

I had to start all over, at your recommendation, by setting my IFR table back to stock. So far, here are my conclusions....

Car felt fastest, and had the best throttle response with the VE table corrected, MAF unhooked, and IFR scaled down 5%.

I hooked up the MAF, and used dynamic airflow averages to recalibrate the MAF. The car felt just as fast above 3k, but below felt slower, and the LTFTs were about -7 under 2500 rpms at mid throttle. No matter how I changed the MAF calibration, it didn't seem to change. So, I changed the IFR table back to STOCK.

After changing the IFR table, the idle seemed unaffected for the most part. 50% throttle and above seems a bit slower (even after dialing in the VE table to right at -2 LTFTs). I added about 5% to the PE table to right about 1.15-1.17 across the board. I haven't hooked the MAF up again. I'm assuming that mid and full throttle seems slower across the board because PE is off now? I dunno.

Another question. Will changing my base running airflow to make sure the idle is dead on AFTER my VE and MAF tuning cause problems? The idle is almost perfect, but hangs just a little at 1100 rpm sometimes on decelleration with clutch in. I don't want to have to start my VE and MAF tuning over again to tweak the idle.

 

I use a wideband and plot AFR correction into the MAF table. Very accurate.

 

I like methods 2 and 3. They worked for me.

 

 

Does having the MAF enabled change dynamic airflow?

If so, or not, why?

I'm just wondering for recalibrating my MAF if I need to disable it again. I've been using method 2. Seems to work, so why change?

 

Method 2:
If you're not using a wideband, then disable the MAF (but keep it connected) as you would for VE/OLSD tuning; DYNAIR now is computed purely from the VE table (which has to have been dialed in already) with no influence from MAF.

Method 1:
When you get hold of a wideband, then do the AFR error correction on the MAF derived by method 2 (if VE is correct then you'll see very little error on the MAF, BEN's will be right on 1.00).

 

More info on MAF recalibration.

Apparently, you need to get your VE table correct in upper RPM ranges, or recalibrating by dynamic airflow is pointless in those ranges.

So, do you recalibrate the MAF or not in WOT throttle scenarios?

If so, how do you tune VE without a wideband for WOT (safely)?

 

I use this method as well, it works VERY well.