Tuning MAF via STFT on 06 tbss

[02NBMFormula]

I just got my VE table dialed in (i think) and just started to try and dial the maf in via logging the "MAF-Short Term Fuel Trim" histogram. the problem is that when i go to log this, it says that this is an unsupported parameter. what am i doing wrong? ive searched but came up confused. i believe i need to set up a custom histogram but i dont know how.

the vehicle is a 2006 trailblazer ss with exhaust and intake. im very new at tuning and appreciate the help. thanks!

btw, using BBA's guide to tune,

[MyLS1Hauls]

This is one of the histograms I use to tune the LTFTs. I'd tune those first, get them close, then if you want, you can tune the STFTs. I don't usually go that far, if I can get my LTFTs within a few % of 0. Hopefully this one works with an E40 PCM. If it doesn't you will just have to redefine the parameters.

Now when you say you "think" you have your VE dialed in, what makes you say that? Did you fail the MAF, tune the VE tables to get the trims very close to 0, and have now re-enabled the MAF?

[SilverG]

All Sensors/PIDs that are used in the Histogram display must be listed in the Table view. If you are trying to see STFT in a histogram with Engine Speed and MAP as the axis then you need all three to be in the Table view. I think the default view already includes these.

One suggestion would be to read the help file. In this case reading the help file/instructions can be very informative.

Good luck and ask questions if you are unsure.

[MyLS1Hauls]

All Sensors/PIDs that are used in the Histogram display must be listed in the Table view. If you are trying to see STFT in a histogram with Engine Speed and MAP as the axis then you need all three to be in the Table view. I think the default view already includes these.

Good point that I forgot to mention. So, to use the above Histogram, you have to be logging RPM, MAP, LTFT, and MAF Hz. Also, the above histogram filters out decel, and WOT trim cells, so they don't skew your results.

[BBA]

Good point that I forgot to mention. So, to use the above Histogram, you have to be logging RPM, MAP, LTFT, and MAF Hz. Also, the above histogram filters out decel, and WOT trim cells, so they don't skew your results.

Exactly, and to further that, the guide I made for my own use actually has you defeat DFCO and PE and forces closed loop in order to get VE dialed in, and the same afterward to get MAF dialed in, then it has you re-enable the DFCO and PE after your done.

[BBA]

This is one of the histograms I use to tune the LTFTs. I'd tune those first, get them close, then if you want, you can tune the STFTs. I don't usually go that far, if I can get my LTFTs within a few % of 0. Hopefully this one works with an E40 PCM. If it doesn't you will just have to redefine the parameters.

Now when you say you "think" you have your VE dialed in, what makes you say that? Did you fail the MAF, tune the VE tables to get the trims very close to 0, and have now re-enabled the MAF?

Just a different way of thinking but I found that if I disable LTFT and tune STFT only, it get's done a lot quicker and the LTFTs fall into place afterward, since LTFT is nothing but a cumulative average of STFT that is used to offset final AFR, which does have the effect of getting close enough to reduce STFTs in the end.

[5_Liter_Eater]

Word. And when you're done tuning, leave LTFT's disabled. That way you don't have to worry about fuel trims being added to PE because STFTs do not do this.

[MyLS1Hauls]

Just a different way of thinking but I found that if I disable LTFT and tune STFT only, it get's done a lot quicker and the LTFTs fall into place afterward, since LTFT is nothing but a cumulative average of STFT that is used to offset final AFR, which does have the effect of getting close enough to reduce STFTs in the end.

Word. And when you're done tuning, leave LTFT's disabled. That way you don't have to worry about fuel trims being added to PE because STFTs do not do this.

So you guys always start out tuning with just the short terms? I know I've heard of some doing it that way, just never tried. Guess I'm the type that sticks to what I've always done...I'll have to give that way a try. Still messing with my MAF curve for my ProCharger to get it really close.

So to the OP, replace LTFT in that histogram with STFT and it should be good to go.

[5_Liter_Eater]

I tune my car in open loop with a wide band but when I tune other cars w/out a wide band I always disable LTFTs and tune with the STFTs. Then I leave LTFTs disabled.

Now having said that, you know you can't tune WOT with fuel trims right? Trying to tune an FI vehicle without a wide band is asking for trouble.

[BBA]

Now having said that, you know you can't tune WOT with fuel trims right? Trying to tune an FI vehicle without a wide band is asking for trouble.

That is and is not exactly right. A Wideband that is calibrated will give you a good estimate of AFR at WOT. Then again, what are you looking for? Max power or a specific AFR?

We all know the LS series make the most power with 12.3-12.4 AFR at WOT, so tuning the PE the way I do, by logging calculated torque doing back to back runs will give you the best AFR for power, and doing this method will never tune you lean.

In short...there are a thousand ways to skin a cat, but to me, a wideband is only an indicator, not a rule.

[PurplePiss]

That is and is not exactly right. A Wideband that is calibrated will give you a good estimate of AFR at WOT. Then again, what are you looking for? Max power or a specific AFR?

We all know the LS series make the most power with 12.3-12.4 AFR at WOT, so tuning the PE the way I do, by logging calculated torque doing back to back runs will give you the best AFR for power, and doing this method will never tune you lean.

In short...there are a thousand ways to skin a cat, but to me, a wideband is only an indicator, not a rule.

You believe a stock LS2 make power down to 12.3 AFR? My experience is they make the most at 12.8-13.0, but you need to run 12.7-12.8 to keep the cylinders cool when you go through all the gears (drag racing). On the highway for a downshift blast for a few seconds, you can get away with more timing and leaner.

What does your 12.3-12.4 AFR curve look like? Fat to lean or lean/fat/lean (2000-6500 rpm).

[MyLS1Hauls]

I tune my car in open loop with a wide band but when I tune other cars w/out a wide band I always disable LTFTs and tune with the STFTs. Then I leave LTFTs disabled.

Now having said that, you know you can't tune WOT with fuel trims right? Trying to tune an FI vehicle without a wide band is asking for trouble.

No, I'm definitely not tuning WOT with trims, just part throttle. I have a wideband for WOT tuning. The tune is pretty close, just wanted to clean up a few spots where the LTFTs were getting close to -5 or so...wanted to bring them up a little closer. WOT, i'm running ~11.5:1. I like to keep it a little rich, considering its a 5000lb brick.

[MyLS1Hauls]

Just did some logging last night with LTFTs off. Came up with this histogram so you can directly paste right into your MAF table. Did multiply by % half and my trims are even closer...Thanks for the info BBA and 5LE.

[Cantalope Kid]

so tuning the PE the way I do, by logging calculated torque doing back to back runs will give you the best AFR for power, and doing this method will never tune you lean.

So you use the following to determine commanded AFR (PE) for max power?

http://www.hptuners.com/forum/showthread.php?t=10358

[02NBMFormula]

so i tried myls1hauls's histograms and also the maf stft high and maf stft low ones and all of them come up with the unsupported parameter, what gives?

[MyLS1Hauls]

so i tried myls1hauls's histograms and also the maf stft high and maf stft low ones and all of them come up with the unsupported parameter, what gives?

You have to be logging the exact data that the histogram uses, or you will get that error. At a minimum to use my histogram, you have to be logging ETC%, MAF in Hz, STFTs, and Fuel Trim Cell. Post your scanner config file and we can take a look at the exact parameters you are logging.

[02NBMFormula]

ok, here is my config. thanks man

[MyLS1Hauls]

Try this one and let me know.

[BBA]

So you use the following to determine commanded AFR (PE) for max power?

http://www.hptuners.com/forum/showthread.php?t=10358

I don't even determine commanded AFR, could care less. I set VE and MAF for close to zero trims (using the guide I wrote and posted a while back). Then I do test runs with delivered torque (calculated torque).

The PE curve always comes out close to 1.95-1.20 across the range. Have found no benefit in raising it at lower or raising it at higher and vice versa.

The guys that have used my tune on widebands have found around 12.3-12.4 AFR throughout the run and their times are always faster than if they run at 12.6-12.8. This was a secret teh Texas TBSS guys tried to keep, but once I did my tunes, word got out. Besides, it's just from experience, who cares what a wideband says if your making more power. My theory is these LS series fast burn heads will make more power if you run rich with more timing.

[04colyZQ8]

Hate to dig up old thread, but I can't fail my MAF sensor?? My stock tune, and all the trailblazer and SSR tunes all seem to have the MAF HZ already set to 0 HZ?? I do not get code P0103 on key on, even though the hertz are set to Zero ??