My MAF seems to read WAY high. I have a 33 mm restrictor in the air inlet that "technically" limits air flow to 27.5 lbs/min. I see 30.5 before the engine reaches the rev limit. Is there anyway the calibrate the MAF to read different, but valid numbers? Would just sliding the scale to the right MEAN anything?
This is a 1.4 turbo swapped into a 1420# fake Jeep.
Last edited by sprinto7; 07-27-2016 at 04:22 PM.
Is the MAF Calibration dialed in properly for your intake setup?
Is actual AFR dead on with Commanded AFR?
I don't know how to "Calibrate MAF". I made the 1.4 run by switching to SD. The MAF still seems to read higher than it possibly could. The MAF is in a 2 3/4" tube with an air straightener.
I will do more searching fro "MAF calibration."
the way you set the maf up is throw stft and afr error.
Build two new graph tabs in your graph, and have them duplicate your MAF Calibration table. Log STFT+LTFT parameter in one of the graphs and log AFR Error in the other.
Then go out and log the car, you will end up using the MAF STFT+LTFT graph when normal driving, and you will end up using the MAF AFR Error graph when at WOT.
After getting some good logs, you will want to use your numbers from your graphs to adjust your MAF Calibration table.
I know there is a good write up on MAF Calibration tuning, just need to dig for it. Also you will need to actually be using your MAF for fueling for this to work properly, so that will require you to re-enable the MAF. And pull it out of SD.
When you decrease the diameter of the inlet the MAF sensor will output a higher frequency for the same amount of air because the cross sectional area is smaller. This is what the MAF calibration table is for, without modifying it the computer is still calculating airflow based off the old intake calibration.Originally Posted by sprinto7
Once you have Commanded match wideband AFR then you will see much more accurate numbers.
This vehicle is not licensed fro road use, so any driving is on the track only.
Here's what I think I know.
1. the 33 mm restrictor will imit air flow to appropriately 27.5 to 28.5 lbs/min. at ANY max RPM.
2. I'm seeing 30 lbs/min at 5000 to 5500 RPM. It will rev to 8K.
3. what I don't know is, "when you say modify the MAF calibration table do you mean slide all the numbers to right, or the left, or something else. Should it read 28 at 12000 hz?
4. I'm ready to take a BIG swing at the numbers if I knew which way to go.
5. it runs ok in SD, but it looks like there is more torque with the MAF.
6. What would happen if I set the MAP fail high to the HZ that equates to 28 lbs? would it switch to SD and keep running?
Last edited by sprinto7; 07-29-2016 at 03:08 PM.
1. I don't know enough about restrictors to help
2. If the MAF Calibration table is properly calibrated, then 30 lbs/min is the correct amount of airflow
3. When saying modify the MAF Calibration. Here is one good write up explaining the steps to do it properly(I know this is for a LNF so the tables look different and you dont have to worry about the MAF Correction table and the EVAP solenoid that he mentions). http://www.hptuners.com/forum/showth...brating-w-PICS
4. Don't just take swings
5. Do you have the MAF failed?
6. Did you mean MAF, not MAP? You do not want to set MAP to fail. If i remember correct, you need to set the MAF fail to zero and set MAF codes to first error (uncheck ses) for SD to be enabled.
cobaltssoverbooster also has youtube videos showing how to calibrate the MAF Calibration table as well. (again they are for specifically for the LNF)
If you do some digging on here there is most likely a good write up of step by step MAF Calibration tuning.
once the base ve is tuned you have to go back and calibrate the maf to match the ve table. then and only then will the calculated values be accurate enough to gauge power output.
2000 Ford Mustang - Top Sportsman
OK, I sort of fixed the MAF error. Our rules require all air enter the engine through a 33 mm reestrictor. One of the best engineered restrictors is 18" long. Hard to get all that length into an 80" wheelbase vehicle. I attached the restrictor to the air filter at the front and then the MAF tube on to the rear of the restrictor. Apparently the fancy restrictor speeds the air back up enough it confuses the MAF. I separated the two with 2 foot of tube. This brought the MAF reading back into reasonable numbers.
Still running Speed Density because it runs fine all the way to 8K. The MAF one shows more cylinder air mass but shuts off at 5200.
The airmass values should be very close between the 2 different airflow calculations, the only time a large difference should happen is quick throttle changes where the engine can either still use some of the air in the intake manifold after letting off the gas, or when the air rushes in to build pressure in the intake manifold, these specific moments are when the pcm will dynamically scale between them to achieve smooth accurate fueling.
In the attached picture you will see unfiltered MAF and VE plotted, youll notice the values are within reason besides under quick changes in air.
VE MAF comparison.PNG
Youll notice the MAF is more jumpy, which is expected as it is usually just before the throttle plate, whereas VE is slower to move under quick changes.
You need to research more on how to calibrate the MAF table, it can be intimidating at first, but air tables should be the first thing tuned in any tune after injector data is set in stone
Last edited by eronq9; 08-15-2016 at 11:38 PM.
That makes sense.
I used the HPT VVE, "tuned" the low load-idle fuel trims with flow rate vs pressure, adjusted WOT AFR with PE, and the 1.4 makes 250 HP (crank) on a Super Flow chassis dyno. AFR seems good to me. I'm sure it could be better, but that's all the time there is available right now.
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