RWTD - I took your suggestion on MAF only CL

[69lt1bird]

I have seen you make this suggestion several times so I figured, what the heck, its nice out so let go try it. I set the Dynamic Air Hi/Lo Thresh to 0 and started driving.

All I can say it, I should done this a long time ago. I smoothed the maf table a little and this thing runs great. I turned my LTFT back on, not sold on leaving them on yet, but I may drive it a while to see what they do. Some far so good.

It even idles better, go figure.

[RWTD]

I'm glad it's working for you well (I wish more would try this). The MAF is always going to be accurate (once it's tuned in properly), whereas the VE can alter based on weather/conditions. Sure, there are correction parameters for VE for these variable conditions, but it's not the easiest to master without GM's equipment and testing methods.

[KLUG'S SS]

I'm glad it's working for you well (I wish more would try this). The MAF is always going to be accurate (once it's tuned in properly), whereas the VE can alter based on weather/conditions. Sure, there are correction parameters for VE for these variable conditions, but it's not the easiest to master without GM's equipment and testing methods.

I have! I actually have been running my truck MAF only over the past couple of weeks and I am quite impressed with the way it has been running. The throttle response overall throughout the RPM range is very nice. I am actually OL MAF only and I am extremely happy with the way my truck is running which is saying alot because I am never happy with it.

[midevil1]

Your MPG's will go up also.....I have seen up to 2 mpg in the trucks.

[jimmyblue]

In my scanning I've seen the MAF frequency output be
pretty unstable / jaggedy while Dynamic Airflow is nice
and smooth. Are you convinced that this is just "noise"
and motor runs OK? I am worried that if fueling follows
too closely I will constantly be swinging lean-rich-lean.
Maybe OK on average, but maybe more prone to sparse
ping etc.?

[KLUG'S SS]

In my scanning I've seen the MAF frequency output be
pretty unstable / jaggedy while Dynamic Airflow is nice
and smooth. Are you convinced that this is just "noise"
and motor runs OK? I am worried that if fueling follows
too closely I will constantly be swinging lean-rich-lean.
Maybe OK on average, but maybe more prone to sparse
ping etc.?

Do you feel that full speed density in open or closed loop will be much more consistent and responsive than MAF only or like the factory setup of a mix between VE and MAF?

[oren m]

MAF only? no VE? Please explain!

[midevil1]

If there aren't any vaccum leaks in your intake tract ( i hope not) It doesn't get anymore accurate than MAF.

[RWTD]

In my scanning I've seen the MAF frequency output be
pretty unstable / jaggedy while Dynamic Airflow is nice
and smooth. Are you convinced that this is just "noise"
and motor runs OK? I am worried that if fueling follows
too closely I will constantly be swinging lean-rich-lean.
Maybe OK on average, but maybe more prone to sparse
ping etc.?

Jimmy, as you know, this of course depends on the type of CAI you have, and of course any MAF modification (screen, no screen, dremel grind?), or if there is any bends in front of behind, or any turbulence causing areas before/after. If the inlet is built properly then the MAF frequency will be nice and smooth. Small subtle jitters are expected, and the pcm has correction for this.

[Matt-B]

Wouldn't taking the "Hi/Lo RPM Threshold" table from the stock value of 2400 RPM to 0 RPM just give the MAF more (but not 100%) control?

I thought the table that would give the MAF 100% control is the "High RPM Disable", which is set at 4000 RPM stock.

[69lt1bird]

RWTD,

Matt-B has a good question. I use the way I did it to tune the MAF only but also have it in ope loop, for truly running in a MAF only mode CL, should I just zero out the "High RPM Disable" instead?

[Chuckster]

I'm glad it's working for you well (I wish more would try this). The MAF is always going to be accurate (once it's tuned in properly), whereas the VE can alter based on weather/conditions. Sure, there are correction parameters for VE for these variable conditions, but it's not the easiest to master without GM's equipment and testing methods.

Do you have a more detailed write up here? I'd like to try this..

[RWTD]

RWTD,

Matt-B has a good question. I use the way I did it to tune the MAF only but also have it in ope loop, for truly running in a MAF only mode CL, should I just zero out the "High RPM Disable" instead?

Hmmm, how did you disable the VE actually? Yes, to run pure MAF just set the "High RPM Disable" to zero.

Do you have a more detailed write up here? I'd like to try this..

Can you be more a bit more claritive in what you're asking? Are you asking for a "how to" on how to tune the MAF? If so, there's plenty of resources here using "Search". Sorry, not trying to sound like a prick, so please don't infer that.

[5_Liter_Eater]

I think Chuckster means how to run MAF only.

On a 3rd gen it's accomplished by setting the engine/airflow/dynamic airflow/High RPM Disable field to an RPM below idle.

[Sam88gta1]

Its under Engine > Airflow > Dynamic Airflow. Set High RPM Disable to 0 rpm.

[waynehartwig]

What is the benifit or better yet, negatives to running pure MAF?

In other words, why or why not would I want to do this? If it's such a good thing, then why isn't this way all the time?

Do I also need to do anything else if I just "Engine > Airflow > Dynamic Airflow. Set High RPM Disable to 0 rpm"? I'm running a pretty much stock tune. Some PE/timing/shifting work, but that's about it.

I'm new to tuning. Have no issues in trying something new if there is a benifit for it and I'm not going to mess something up. Know what I mean

[RWTD]

waynehartwig, what modifications do you have? Do you understand the concept of VE, as well as MAF, and how each are tuned?

There really isn't any negative. Some would argue it's more accurate, easier to tune (it really is), and more stable (it definitely is this, as you set it and leave it, and you will never have to retune for outside condition/weather changes). The one potential downside is that if you disable VE and the MAF fails (like Germ-X, there's a 0.01% chance that'll you'll still have bugs on you, LOL), then the engine would not really run. If you have your laptop with you, that's not a problem (switch VE back on). Seriously tho, a MAF failing is about the same chances as gettings truck by lightning.

When you say "some PE work", did you adjust the PE to obtain desired AFR WITHOUT adjusting the MAF transfer? If so, that's a no no. You set the PE to Command desired, and then you dial in the MAF transfer until that Commanded becomes Actual AFR.

[Chuckster]

I think Chuckster means how to run MAF only.

On a 3rd gen it's accomplished by setting the engine/airflow/dynamic airflow/High RPM Disable field to an RPM below idle.

Yes you are correct.. and thank you for being patient..

I am JUST getting back into the tuning game after 5 years.. I know I sound like a dumbass newb.. But I Swear to god.. I used to help others tuning with the MAF Translator and logging with Autotap, then on to LS1edit.. Etc..

Anyway.. I promise to listen and learn...

So once the VE is disabled what is the next step in tuning? What am I logging at that point and what trends am I looking for? By the way.. I am in FL with the worst air in the country.. Does this still make sense to disable the VE?

[waynehartwig]

waynehartwig, what modifications do you have? Do you understand the concept of VE, as well as MAF, and how each are tuned?

There really isn't any negative. Some would argue it's more accurate, easier to tune (it really is), and more stable (it definitely is this, as you set it and leave it, and you will never have to retune for outside condition/weather changes). The one potential downside is that if you disable VE and the MAF fails (like Germ-X, there's a 0.01% chance that'll you'll still have bugs on you, LOL), then the engine would not really run. If you have your laptop with you, that's not a problem (switch VE back on). Seriously tho, a MAF failing is about the same chances as gettings truck by lightning.

When you say "some PE work", did you adjust the PE to obtain desired AFR WITHOUT adjusting the MAF transfer? If so, that's a no no. You set the PE to Command desired, and then you dial in the MAF transfer until that Commanded becomes Actual AFR.

Honestly, I know enough to be dangerous - and even can call me a hack. I have next to no knowledge of it and the same limited experience. Just being honest.... I have engine building/tuning experience, but it's all old school distributor/carb stuff.

I'll post my tune so you can see some of the changes I've made. But for PE I've cahnged the delay/enable RPM to 0, but upped MAP to 75 (from 55) and tightened up MAP HYST to 3. Oh, and I also changed PE Enable to 75% instead of 84% and the enrichment rate to 2% from .05%.

I do have a wideband. So I disable VE and just use MAF. If I notice my wideband going lean/rich, do I just note when and go in and change the MAF calibration numbers to correct it?

EDIT: just to be clear on the file name. The tune is a modified Edge tune. The biggest thing I changed was the spark tables, because I had a pretty good ping at partial throttle on hills. Give it a bit of gas, and the audible ping would go away. I also increased the timing under heavy loads a few *'s from Edge's.

[Eagle]

Reversion associated with larger camshafts doesn't cause issues? My MAF does not track smoothly, not at idle, not @ WOT, not @ cruise. I've seen a few larger cammed cars have this same issue. My understanding is that this is why a lot of folks go to SD tunes...

You've got my attention though. I'll go search a bit and see what I can learn on this MAF only tune concept.