MAF Tuning and data-logging using LTFT's/STFT's

[1KillerSS]

Hello and thanks for reading. I have been tuning my car a little bit at a time as I feel more comfortable with each process. As some of my previous postings have stated. I have had experience tuning using a few other programs on different cars. However I am new to GM's and LS3's and even newer to E38 PCM's

I started following bluethorp's thread located here.... http://www.camaro5.com/forums/showthread.php?t=196696 this and the tons of information on the web is extremely helpful, yet I still have some unanswered questions.

I do not have a wideband O2, that will come at a later date. I am attempting to tune using my LTFT's/STFT's

When I tuned my VE tables using this method I was able to get my trims +/-4 like suggested. It took me several logging sessions, but I believe I succeeded. While tuning my VE tables I logged for ten min each session and drove like I normally do with a few WOT runs.

I hope that was correct, in fact if that was incorrect them someone please correct me, the tutorial I have been following does not really get specific on under what Driving conditions and for what length of time I should log.

My question for MAF tuning is, How long should I log and under what conditions do I need to log? would I do the exact same for MAF as I did for VE?

Also, how much different is my curve going to look from stock? I ask because so far the curves I've seen on aftermarket CAI's look noticeably different from stock, yet my curve seems to look very close to my original stock curve, and thats with several logging and tuning sessions, more than a dozen. Not to mention my trims are still off.

The tutorial lead me to believe that VE tuning was harder than MAF tuning, and that I would need to spend more time data-logging to get my trims where I wanted them, as compared to MAF tuning. So I feel like I am chasing my tail and need a little help. I have done both, normal driving with a few WOT runs over several minutes, and then strictly a few WOT runs. It still seem as though I am not making progress.

I have done as stated in the tutorial:

1. “Dynamic Airflow”, change “High RPM Disable” to 2, and 'High RPM Re-enable” to 1.
2. COT to disable
3. DFCO enable temp to 493 degrees
4. Power enrichment enable MAP to 75

I first logged my LTFT's and multiplied by % one time..... with my fuel trims reset
Now tuning STFT's, I have set long term fuel trims to "off" and reset fuel trims for each session, and multiplied by %-half, as stated in bluethorps tutorial.

Modds are simple:

Airaid CAI
Vmax Ported TB
BBK shorties

Sorry for the long posting and again thank you in advance for reading and your help.



**EDIT**Spelling/Grammar

[granatl]

At least on the 2010-2013 v8's, these cars use a E38 computer.
They do not contain VE tables, but rather key data points and then use formulas to derive a VE cell on-demand. Mind you, I don't recall the exact number off-hand, but if the calculated VE value and the MAF value are within x% of each other, this allows the car to run smoother (assuming both VE and MAF are enabled).

To convert the VE formulas into a human editable VE table (and back again), you download the Bluecat VE<->EQ program. This is not for the lighthearted individual. I messed with this on-and-off for well over a year.

Finally last week, I used HP Tuners to flash my OS to an older one, so that I had a real VE table. Once I had the real table in place, I then used the Scanner histogram for VE to capture and then adjust the various cells. I then used Bluecat's tool and copied my VE table into and then extrapolated the number for the higher boost area. I re-flashed back to my modern Camaro OS and then overlayed the Bluecat derived formulas. The car runs FAR better than it has in a long time.

Now, taking a step back. The VE numbers are made from MAF+intake temp+MAP pressure * magic multipliers, etc. So, as has been suggested on the HP Tuners board, it makes the most sense to plug in the formula into the Scanner and let it derive the VE map for you in a histogram (then interpolate the missing cells). IDK if I can post the formula w/o PO'ing people, nor have I thoroughly tested its accuracy.

[1KillerSS]

I got the VE part down, and yes they use 8 tables instead of one....using the conversion tool you can generate one VE map, edit it and resend it back to all 8 tables....this part was easy to me. its more a question of data-logging...

Ill try to be more direct with my questions.


1. how long and under what conditions do I want to log? for MAF only tuning? basic daily driving? WOT runs? how long to log?

2. What kind of variation can I expect from a aftermarket tune compared to a stock MAF table...as I stated most of the charts I have viewed look different from stock....not a whole lot different but definately a noticable difference...mine barley looks different at all. Of course I am not done tuning yet but that leads me to my other question

3. Am I following this guide correctly for MAF tuning, because everybody tells me its the easiest and it seems as am having the more difficulty with this then the 8 different tables for VE tuning.

[granatl]

1) As long as it takes for either (a) the histogram to reach pretty much a steady state (cells are only changing by .1-.3) or (b) correcting those cells that are >10% on either side of zero. Drive uphill, downhill, highway, stoplight to stoplight... If the histograms are going bright red, just stop, copy, paste special, reflash, repeat. (bright green isn't doing you any favors either)

2) IDK

3) It looks to me that you're correctly disabling VE, DFCO, ...

The graph of the MAF frequency (in full screen) will have an S-shape to it. Visually look for aggressive dips/spikes. It should generally be rather smooth, end to end. Additionally, look at cell-by-cell. Is the value reasonably in between its neighbors?

I've had a rotten time with the MAF tuning. I used to think I was picking up air turbulence, but now that I have a MAF screen, so it must be something else. I'll get my numbers within 2% (favoring negative rich), then the next day they'll be wacky again. It has been getting better lately though.

Be aware that there's a discussion on the HP Tuners board how after the first 10 minutes of flashing a new tune, the car chooses to run rich. So let it idle or don't bother data logging for at least 10 minutes.

[Tampa Tuning]

After each upload, it takes about several minutes for the LTFT to start producing accurate information.
On my mail order tunes, I tell guys to upload the tune, let it idle to 2 minutes, take it for a 30 minute drive with normal, spirited, and WOT driving, park and let it idle for 2 minutes, and send me the scan for inspection.

[1KillerSS]

Thanks to both of you. That's a push in the right direction.