Tuning with a MAF
Tuning with a MAF For my camaro I did all of my tuning is SD mode. Now with the Z06 I want to use the MAF mainly because the car is all stock. What is the correct way to go about modifying the part-throttle fuel curve so that the pcm does not just adjust to any changes you make? As far as WOT tuning goes, it works the same way, right?
I looked through the stickies, but I didn't see this.
I looked through the stickies, but I didn't see this.
There a MAF table. You have to change the values there. The PCM will always use the NB O2 to ajust fueling at part throttle. Do you have a Wind band O2? If not get one. Use it to tune PE.
I had just thought I read that tuning changing the MAF table was not the correct way because you are actually telling the PCM there is less air coming in(or more).
IMHO, you need to tune the car in SD first, get your trims in shape/af your looking for. Get it all sqaured away. PE, all of it. Then re-enable the maf, and scale the maf table to get your trims back to where you need then.
Changing the fueling values, with stock pump and injectors, is not the right method, so you left with the airflow equation being off.
Ryan
Everyone always says changing the IFR table is so wrong, but who is to say the injectors are flowing what they are rated at. Why is the IFR of an injector never off? I just put a set of 60K mile injectors on a flow bench and let me tell you they did not flow anywhere near what they were rated at. Even after ultrasonic cleaning they were off, not as far, but still off.
You need to calibrate the MAF, why would you not calibrate it? If you don't calibrate it then your commanded PE AFR is not going to be your real measured PE AFR...likewise with your cruising. If your MAF table is off your fueling will be off.
Trending Topics
TECH Junkie
Joined: Dec 2001
Posts: 3,242
Likes: 0
From: Lakeland, FL
get a wideband, measure actual afr vs commanded afr and then multiply the MAF table by the % difference for all the areas, with hptuners there is already pre configured histograms for this. Also remember to disable VE while doing this.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo TECH Junkie
Joined: Dec 2001
Posts: 3,242
Likes: 0
From: Lakeland, FL
To disable the VE you have to set the MAF lookup table to start at 0 rpm instead of 4000, Do this under Airflow/Dynamic Airflow, Then its High RPM disable to 0 instead of 4000
this is hptuners though not sure about efilive
this is hptuners though not sure about efilive
Everyone always says changing the IFR table is so wrong, but who is to say the injectors are flowing what they are rated at. Why is the IFR of an injector never off? I just put a set of 60K mile injectors on a flow bench and let me tell you they did not flow anywhere near what they were rated at. Even after ultrasonic cleaning they were off, not as far, but still off.
Performance. Diagnostic. Spark Table. Ect.
You really want a good airflow calc.
Plus, we don't know all the inner workings of the PCM's OS. Unknowns could depend on it.
If I knew someone who would flow test my injectors I would be up for it...
"Everyone always says changing the IFR table is so wrong, but who is to say the injectors are flowing what they are rated at. Why is the IFR of an injector never off?"
It can be off, but you have to start somewhere in your assumptions.
Read this to get your head wrapped around it:
http://redhardsupra.blogspot.com/
Specifically this months blog on the 3 airmass models.
It can be off, but you have to start somewhere in your assumptions.
Read this to get your head wrapped around it:
http://redhardsupra.blogspot.com/
Specifically this months blog on the 3 airmass models.
All the tuners I talk to around here say I am making a big mistake running in OL SD. My dyno sheets say other wise. What works for some doesn't work for all, be it right or wrong, you can't argue with results.
So, to sum it up, nobody agrees on how to do this?
With only a VaraRam added to the Z06the Ltrims are +10 to +19. Is there not a simple way to add the fuel in correctly without going through a whole speed density tune (50-100 miles)?
Even if I spend all the time to do that, how do I know what values to use to scale the MAF afterwards without a wideband?
With only a VaraRam added to the Z06the Ltrims are +10 to +19. Is there not a simple way to add the fuel in correctly without going through a whole speed density tune (50-100 miles)?
Even if I spend all the time to do that, how do I know what values to use to scale the MAF afterwards without a wideband?
So, to sum it up, nobody agrees on how to do this?
With only a VaraRam added to the Z06the Ltrims are +10 to +19. Is there not a simple way to add the fuel in correctly without going through a whole speed density tune (50-100 miles)?
Even if I spend all the time to do that, how do I know what values to use to scale the MAF afterwards without a wideband?
With only a VaraRam added to the Z06the Ltrims are +10 to +19. Is there not a simple way to add the fuel in correctly without going through a whole speed density tune (50-100 miles)?
Even if I spend all the time to do that, how do I know what values to use to scale the MAF afterwards without a wideband?
how will you know if the changes you made are
having a negative or positive effect?
i know with efilive you can log SAE.MAF (lbs/per.min or grms.per.sec)
and paste the values or,
you can multiply by BEN with WBO2.
i wouldn`t put to much in LTFTs, they can be off
and your fueling can still be right on.
So, to sum it up, nobody agrees on how to do this?
With only a VaraRam added to the Z06the Ltrims are +10 to +19. Is there not a simple way to add the fuel in correctly without going through a whole speed density tune (50-100 miles)?
Even if I spend all the time to do that, how do I know what values to use to scale the MAF afterwards without a wideband?
With only a VaraRam added to the Z06the Ltrims are +10 to +19. Is there not a simple way to add the fuel in correctly without going through a whole speed density tune (50-100 miles)?
Even if I spend all the time to do that, how do I know what values to use to scale the MAF afterwards without a wideband?
P.S. whatever you do, get a WBO2 first!
I'm sure a more experienced tuner will chime in but here's an elementary look at it from my part. If you haven't changed the injectors then I can't see why you'd want to tamper with the IFR. If the MAF is stock, again, why disrupt the MAF tables, I'm pretty sure the engineers at GM spent sufficient time in developing airflow tables to properly dial in the MAF. The 'simplest' way to change things then would be to tune your VE table since you altered the amount of air entering the engine at any given time via your Vararam. Neither the amount of fuel your injectors are spraying, nor the volume of air your MAF is calibrated to measure has changed, what your changed is the actual amount of air ingested by the engine at a given moment, hence the change in VE.
P.S. whatever you do, get a WBO2 first!
P.S. whatever you do, get a WBO2 first!