Calibrating the MAF
Thread Starter
Le Mans Master
Joined: Oct 2001
Posts: 5,577
Likes: 3
From: Southern Maryland Maryland
Calibrating the MAF
We have always used a standard process to retune the MAF to calibrate the MAF to your combo. All of the tunes I have looked at have had some very different maf curves than what we usually see once we recalibrate them. What is everyone else doing?
Phil
Phil
Le Mans Master
Joined: Aug 2002
Posts: 8,472
Likes: 38
From: Houston TX
St. Jude Donor '11
First I disable the MAF and dial in the VE. Once that is good I re-enable the MAF and log the LTFT. If it is pretty consistent I scale the whole table up or down. Then I used to log MAF freq and LTFT and plug everything into a 4th order polynomial in Excel. Very time consuming. Recently I came across some HPT histograms for MAF % error VS LTFT or STFT and I believe there was one for commanded AFR error as well. It's a single row with the MAF frequencies as columns and the value in each column is the respective average % up or down the LTFT or STFT is in that frequency range. So you just drive around, the more the better, and cut and paste the values as multiply by % into the MAF airflow VS frequency table. Rinse lather repeat.
Last edited by 5 Liter Eater; Jul 25, 2006 at 05:32 PM.
Le Mans Master
Joined: Aug 2002
Posts: 8,472
Likes: 38
From: Houston TX
St. Jude Donor '11
Heres the thread with the HPT Scanner config and LTFT and STFT histograms. Looks like I lied about a commanded AFR one though. Shouldn't be too hard to tweak the histogram to be % AFR Error rather than LTFT or STFT though for use with a wideband. I have to admit my ignorance of the histogram configuration. I just borrowed these from soundengineer. this thread did open my eyes a little though.
http://www.hptuners.com/forum/showthread.php?t=5564
http://www.hptuners.com/forum/showthread.php?t=5564
Thread Starter
Le Mans Master
Joined: Oct 2001
Posts: 5,577
Likes: 3
From: Southern Maryland Maryland
Here's what I do....
Dual widebands plumbed back into laptop
Averaged both WBs and input the averaged Air Fuel Error
Logged into histogram for MAF frequency
Do a nice 20 minute drive filling the VE table with mininum of 20 hits per cell
Input the new MAF table and reenable the O2s. Whats funny is usually the stock O2s are off all over the place pretty consistent. My MAF tables have a similar curve but are very different than a stock one. Dialing in the VE and MAF table should only be done with a wideband O2, your accuracy is only as good as the sensor your using.
Phil
Dual widebands plumbed back into laptop
Averaged both WBs and input the averaged Air Fuel Error
Logged into histogram for MAF frequency
Do a nice 20 minute drive filling the VE table with mininum of 20 hits per cell
Input the new MAF table and reenable the O2s. Whats funny is usually the stock O2s are off all over the place pretty consistent. My MAF tables have a similar curve but are very different than a stock one. Dialing in the VE and MAF table should only be done with a wideband O2, your accuracy is only as good as the sensor your using.
Phil
Le Mans Master
Joined: Aug 2002
Posts: 8,472
Likes: 38
From: Houston TX
St. Jude Donor '11
Hmmm, Well I don't tune with a wideband (yet) so I can't speak to the differences between the NB and WB sensors. Figuring you trust your WBs more I know I have seen a thread about recalibrating the NB O2's to account for headers, different distance from exhaust ports, etc on the HPT forums. Without that, calibrating the MAF to the WB doesn't do a whole lot of good if the NB sensors are foing to throw off the fuel trims, especially to the positive side.
Thread Starter
Le Mans Master
Joined: Oct 2001
Posts: 5,577
Likes: 3
From: Southern Maryland Maryland
Originally Posted by 5 Liter Eater
Honestly I'm surprised to see you still messing with the MAF Phil. I would have thought you'd be an SD guy through and through by now.
Le Mans Master
Joined: Oct 2001
Posts: 5,145
Likes: 125
From: The Motor City
I thought that we used to log Dyn Cyl Air and MAF Hz and use it to form a new MAF curve. This is what I did for my car and it came out pretty well. I gathered all of the data while SD tuning, then used Excel to fit a curve. Then used that curve to get the numbers for the MAF table.
-Matt
-Matt
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Every 2027 Corvette Engine Explained
Joe Kucinski
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Verdad Gallardo
10 Ugly Corvettes That We Still Kinda Love
Joe Kucinski
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Premium Supporting Vendor
Joined: Mar 2001
Posts: 5,241
Likes: 21
From: Knoxville Tennessee
Originally Posted by Scooter70
I thought that we used to log Dyn Cyl Air and MAF Hz and use it to form a new MAF curve. This is what I did for my car and it came out pretty well. I gathered all of the data while SD tuning, then used Excel to fit a curve. Then used that curve to get the numbers for the MAF table.
-Matt
-Matt
Pretty much what I have done as well.
Former Vendor
Joined: May 2003
Posts: 1,313
Likes: 4
From: Livermore CA
VE only first, including WOT pulls on the dyno to even dial in the high load stuff to desired PE settings. Enable MAF in open loop still, log error % from AFR on wideband just like VE, including wot pulls. Enable the rest of the closed loop system and you will find its pretty dead on. Check all your work again on the road when you are happy. Works pretty good.
Rick
Rick
Supporting Vendor
Joined: Jun 2004
Posts: 692
Likes: 13
You can also tell the VCM to use the MAF only and ignore the VE table, or use the VE table for the entire range.
VE tuning:
Dynamic Airflow Hi RPM Disable = 8000
Hi Lo thresh RPM = 8000
MAF tuning:
Dynamic Airflow Hi RPM Disable = 300
Hi Lo thresh RPM = 300
Hi TPS Delta 100%
Hi MAP Delta 100
Return values to stock when you are done.
VE tuning:
Dynamic Airflow Hi RPM Disable = 8000
Hi Lo thresh RPM = 8000
MAF tuning:
Dynamic Airflow Hi RPM Disable = 300
Hi Lo thresh RPM = 300
Hi TPS Delta 100%
Hi MAP Delta 100
Return values to stock when you are done.
