I was talking to a guy yesterday, and he mentioned something to me about how to dial in the STFT and LTFT's. I was talking about adjusting the injector slope in order to modify the trims, but he said that I should start with adjusting the MAF first, and only then should I make adjustments to the injector slope, in the event I can't get the trims dialed in with the MAF.

Which way should I adjust the MAF, should I try this? Lets say my LTFT's are showing +9. How would I adjust to compensate?

 

Do yourself a big favor and PLEASE don't try to get your fuel trims back in line by raping the IFR (injector flow rate). This is a real hack job way of tuning.

What are you using Hptuners EFI Live?


The MAF on GMs reads in hz (hertz), frequency and the more airflow across the sensor the higher the frequency. you log plotting either AFR error or fuel trims against the MAF table. Using your example if you had a +9 fuel trim in one particular cell you would need a correction factor by multiplying that cell by 1.09.


The only time the injector flow rate "should" be changed is to match the flow rate of some different or larger injectors that are installed.

 

you're using a Predator... you can not adjust anything for the MAF...

you would need to get a custom tune done for your truck to have it done correctly...

only way you can adjust the fueling using the predator handheld is yes - the injector slope.... which is still better than any other handhelds out there that don't let you adjust your fueling AT ALL.

but yes, to get the MAF sensor table re-scaled, you'd need to get a custom tune done by a diablosport CMR custom tuner, like myself...

 

Yes this is true and good that u guys offer some option there. Please don't take offense to my comment it just happens to be a method that I strongly disagree with but you guys by far do have the best handheld option out there!

 

Thanks guys. I was actually misinformed, as in being told my Predator had the capability to adjust the MAF sensor. I hadn't had time to verify that, as i've been busy this week.

 

haha... np man, there was no offense taken...

I just wanted to explain it a little better for the others...

and yes, it's a work-around and does work, but is not the BEST way to do it... hehe...

 

Cool. Also I was just assuming that he was using EFI Live, etc... and that's not always the case.

Also I am one of those type of people with a very blunt brutally honest type of personalities and how I may make a comment or statement about stuff sometimes might come off like I am being a ***** or nasty about something but it isn't like that at all and I like to make sure that everybody knows that.

 

Another vote for the MAF. Actually you need to disable the trims, unplug the maf and start with the v.e. Once its dialed in, plug the maf back in, and repeat the process until it is in the 0 to -5% range imo. Like Klug said, lean trims like +9 means you need to scale the maf table up by approx 9 %. I tune WOT the same way, I don't believe in fudging the p.e. to get the fuel in line. I think commanded fuel should equal actual fuel, and you HAVE to tune the MAF to get there.

 

yep, absolutely.... I hear ya...

 

I'd listen to Monte, he knows his ****. He's tuned my truck once, and now again due to my nasty air leak! He's a damn good tuner