MAF MAP mode Runs Lean in WOT, but each are fine separately... ?

[10_SS]

Running the 2bar SD tune on a 2010 LS3 E38 with a Whipple.. been fine for a year, now trying to enable Dynamic Airflow but its not going well at all.

I tuned the MAF only and it runs great, within 1-2% from perfect, also tuned the SD tables with MAF disabled, and unplugged, and also have them within 1-2% from perfect, they both seem pretty consistent from day to day.

Now when I enable MAF MAP "Dynamic" mode up to only 1900rpms for testing, the WOT fueling is very lean, it starts only slightly lean right off idle, then by 1800rpm it's about 12-15% lean, then over 1900rpm it comes back to normal, 1-2% rich since it's back to pure MAF. If I add ~15% fuel to the SD tables in this region without making any other changes then fueling is ok... but then my SD table has huge spikes, and is obviously not right...

I don't really have any values adjusted in the "Prediction Coefficients" below the "Dynamic Airflow" enable/disable...


What do you think? Confused... Tune attached...

2B095 MAP MAF LEAN.hpt

[BigDaddyCool]

The MAP sensor is pretty slow. I've found in Dynamic it only really settled on steady state correctly.

Dynamics a nightmare honestly. Try a ZL1 maybe dynamic table wise.

Also maybe make sure your your Dynamic VE to MAF table is set right. Change it to 1.0 and then log it in mixed mode and workout a variance by ECT etc and set it in that table. That helps a lot with VE being wrong despite being right on it's own.

[10_SS]

THere are some huge differences in the Prediction Coefficients.. .where my stock tune has alot of 0.000's in the gains, the ZL1 tune has big numbers... thanks for the suggestion I'll try it out. If it ends up being too much hassle I'll just leave it in pure MAF mode.. was running really good.

[BigDaddyCool]

THere are some huge differences in the Prediction Coefficients.. .where my stock tune has alot of 0.000's in the gains, the ZL1 tune has big numbers... thanks for the suggestion I'll try it out. If it ends up being too much hassle I'll just leave it in pure MAF mode.. was running really good.

My stock setup is a bit off an odd ball. Even if I have dynamic disabled after 3000rpm exactly full throttle the dynamic airflow I log goes from MAF numbers to VE........ despite being disabled.

I have another tune somewhere which primarily only uses maf for the dynamic which i can send you, the ZL1 is probably not the one i was thinking of.

[griffincox]

Did you ever solve this? I have dialed MAF and VE but now enabling dynamic I have the same issue. Running very lean. What gives?

[mowton]

Make sure you reset your fuel trims at the start of each tuning sessions (MAF and VE) after you update your tune......even if you are running in open loop.....especially if you are tuning in closed loop with the trims!

Ed M

[griffincox]

Well, I believe I solved the problem I was having by zero'ing out all 10 Prediction Coefficient tables. This leads me back to a thread I started months ago. It sounds like very little is known about these tables, at least mathematically. Unfortunately I am not good enough with math to make sense of em, but hopefully sometime soon one of you wizards can make sense and use of what seems to be some powerful variables in the OS for predicting airmass.

http://www.hptuners.com/forum/showth...n-Coefficients

[10_SS]

No i havent had time... It runs good enough in MAF mode for now. My Prediction Coefficients are very low, most are less than 0.9... And only Base, Current, and Corrected have values.