This may be possible with the 9415 Xcalibrator 2 as well, but using ExtremeTune and the Excalibrator 1, I was able to match the curve on my cut MAF.

3.0 MAF sensors are within a range after the MAF mod such that the normal short/long term fuel trims can compensate.

However, this is not ideal. For example, my MAF (and most cut MAF's) generally report less flow than there actually is after cutting, so they tend to want to run lean.

The O2 sensor feedback compensates for this.

However, the error is greater with greater flow. On 4.0's the error can be so great the fuel trim pegs and you get lean codes thrown after awhile.

On my 3.0, I would get a brief pinging episode if I floored it suddenly. The fuel trim required with wider throttle settings was greater so until the system "caught up" I would be lean.

By using ExtremeTune I was able to match the curve. Basically, MAF's are non-linear but follow the square-root ranging curves that most air flow sensors have.

SCT has a system where you give 3 points of correction at idle, medium and full throttle and the software reconstructs a curve that "fits" those 3 points.

I made my two "best guesses" based on what I saw in data logging and my first solution worked. My second one was too rich.

I'll make some graphs later and post them here.

But, based on real-time watching of the short and long term fuel trims using my Palm and the ELM interface, long term fuel trim remains at ZERO (perfect) and short term bounces between +/- 4 generally. This is outstanding since I used to get numbers in long term as high as 10 to 14. This is on both banks.

What this means is that if you have the ability to adjust these parameters, you can do a MAF mod to open up some airflow and then recalibrate for the changes that result.

Good news for 4.0 owners who want to save some money and already have a tuner that can tweak this.

I also increased the shift pressure a bit more and man what a pleasure it is to tromp on the gas. The downshifting is much quicker and snappy. No more "lag" when you tromp down.

This is just using the "user" adjustment features on a stock tune. I can't wait to see what a "real" tune feels like!

Anybody local with a 4.0 and a tuner want to be my next "guinea pig"? We'll use my cut MAF sensor in your housing and verify that it will work well using your tuner to adjust your truck. Then you'll have more airflow, but good ratio.

 

wow.. always amazing.. good info...

 

John...I want you to tune my truck! If you come to the Tri-State Meet you should bring the stuff to do it. Hehe. Interesting data though.

 

I wish I did know more about tuning, lol. It's not that easy when you look at some of those tables and stuff. I think it's an intersection between "art" and "science" and that's why there's such variation in the quality and results.

But thanks for the comments, lol.

 

dont know if youd be interested in using me, i've already got a cut MAF on a 4.0 and have the xcal 2

 

Problem is you're way out there. You can try this yourself. If you have the 9400 and you can get your tunes from your dealer in .xtr format, you can do it just like I am.

Now, with the Xcal 9415, or a 9400 with .ll3 tunes; you'll have to find the air/fuel settings on your menu. But look at this screen for reference:



Observe that I've not touched the idle setting, but I boosted mid throttle moderately and full throttle more. This setting compensates my mod handily.

Now, on the 4.0 it's more extreme. You may need to boost mid throttle more and full throttle a lot more.

Basically, monitor LTFT1 and LTFT2 (long term fuel trim 1 and 2) after making a change and adjust until you get the lowest numbers you can, zero preferred. At that point you've got a nice match.

If the LTFT's are trending positive, you are running lean and you need to enrich more. If they are running negative, you're running rich and you need to enrich less.

Higher numbers on the adjustments above equate to a richer mixture.

My vision for doing this was someone local so I can be there for the testing and all -- but you can try this yourself if you like and it shouldn't be too hard to get a better trim than what results from the cut MAF.

 

wow now I feel dumb.

 

John,
I did the MAF mod about a week ago and it seems like it helped alot on the 3.0. I got an xcal2 and i wanted to know more details or i guess the settings you change to account for the maf mod.

 

First you have to know what you've got, then you can change it.

Datalog the STFT1, LTFT1, STFT2, LTFT2 PID's. I believe that's the acronyms used by your XCAL2. They stand for the long term and short term fuel trims for banks 1 and 2.

They may be a little different between bank 1 and 2 -- but not a lot.

What you're seeking is that everywhere in your throttle and RPM range, the LTFT (long term fuel trims) remain at zero. This indicates you're in pretty good match between the MAF and the injector firing to hit the target fuel/air ratio.

You can also try to minimize STFT, but it jumps around enough that it may not be possible to really, truly "tune" it to zero.

Anyway, once you know what throttle ranges are off, you can adjust the air fuel ratio for idle, part throttle, or full throttle up or down to compensate for the MAF curve being off and "normalize" it. Exactly how you do that on the 9415 XCAL I'm not sure -- but it can be done.

I don't have a datalogging tuner, so I use an external OBD2 interface and laptop or Palm software to watch the trims. Same thing, just less convenient!