LS1x2

iTrader: (11)

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.

YellowToy/A

iTrader: (1)

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.

LS1x2

iTrader: (11)

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).

01FbTaWs6

iTrader: (12)

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.

slow

iTrader: (7)

If the pcm thinks there is more air than what is really coming in, you need to lower it.

Changing the fueling values, with stock pump and injectors, is not the right method, so you left with the airflow equation being off.

Ryan

2xLS1

iTrader: (25)

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.

Gh0st

iTrader: (3)

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.

Mike K.

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.

YellowToy/A

iTrader: (1)

Mike is right about the WB. How do you disable VE. I just enable MAF then tune.

Mike K.

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

2002_Z28_Six_Speed

iTrader: (19)

It will be closer. I completely understand what you are saying but why introduce error into the model? Other things depend on an airflow calc.

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...

Viper

iTrader: (6)

"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.

Mike K.

yeah and also,,,, what about min pulsewidth, voltage offset, etc...


How do we figure out all that stuff, it seems pretty important.

vaticano

iTrader: (8)

All the messing around with those tables i've done only proved one thing. Most if not all high impedence injectors wont run properly at any levels below 1.8 ms. You can get them to run there but not effectively. I'm no tuning guru, but my 42's 60's and now 79's all react the same to messing with the small pulse adders. I am no longer concerned by what people say is right or wrong. I need to do what ever it takes to get the car to run right. I needed to pass emisions so, I lowered my fuel pressure to 26 psi. made all the small pulse adders negative, and I still have fuel dumping in when I release the throttle above 2500 rpm. I did see a few 1.4 ms pulses but then the injectors couldn't flow any fuel at those low pulse widths so afr went to 20.9%. Meaning no fuel was able to come out at all.
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.

LS1x2

iTrader: (11)

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?

shoemike

iTrader: (25)

you really need a WBO2 for this,
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.

VTC_WS6

iTrader: (9)

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!

LS1x2

iTrader: (11)

Simple enough. That actually makes a lot of sense. At some point don't the VE tables max out?

VTC_WS6

iTrader: (9)

Of course, but simple bolt-ons won't have you near the limits of the map so you should be fine in that respect.

slow

iTrader: (7)

at steady state, the maf is being used for airflow calcs. So even with the VE table perfect, if the maf is not correct, your fuel trims will be off.

Ryan