What to Tune First

[SSpdDmon]

For this part are you supposed to force OL, or stay in CL?

That assumes you put B0120 down to something low like 100 rpm. And yes, you still force open loop with that method, which means setting op. temps to 14.63 and setting PE where you want it. This simulates closed loop. If you need PE to come on sooner, adjust the PE Enable table by lowering the TP% to nothing greater than 35~40%.

[Aint Skeered]

by tuning this way, do you leave the VE table alone? just play with injector flow rate is How my car ws tuned by a professional tuner and when I posted it on here last year when I first bought EFI live , everyone told me to start fresh and get away from the injector flow rate tune. I have to say, It worked pretty well as for WOT .

Does Ve Table play a roll still with this method?

[SSpdDmon]

by tuning this way, do you leave the VE table alone? just play with injector flow rate is How my car ws tuned by a professional tuner and when I posted it on here last year when I first bought EFI live , everyone told me to start fresh and get away from the injector flow rate tune. I have to say, It worked pretty well as for WOT .

Does Ve Table play a roll still with this method?

This process simply reverses the order of tuning and leaves the MAF curve stock since it should still have it's screen.

The idea is, drop the B0120 so you're in MAF only mode and tweak the IFR until you end up with an accurate representation of your IFR table. When you're done, it should be fairly linear. If not, there may be other injector tables that are in need of adjustment.

Next, you go speed density like normal (kill the MAF with Fail Frequency). Using your new IFR table, dial in the VE table. Once you're done, you should be able to re-enable the MAF, restore B0120 to stock or there abouts, and not have your fuel trims sky rocket like everyone always does.

Why do it this way? Personally, I'd much rather adjust the handful of IFR cells rather than the 84 MAF cells. Plus, I find it hard to believe that a cam & heads can drastically alter the MAF cal. You put the stock lid and bellow in and you'll still have to adjust the MAF curve with the other way. That to me says something is fishy and something is being fudged. So, fudge the MAF or the IFR??? I say fudge the IFR. Too many other tables rely on what the MAF reports (timing, trans pressures, etc.). That should stay stock IMO.

[405HP_Z06]

This process simply reverses the order of tuning and leaves the MAF curve stock since it should still have it's screen.

The idea is, drop the B0120 so you're in MAF only mode and tweak the IFR until you end up with an accurate representation of your IFR table. When you're done, it should be fairly linear. If not, there may be other injector tables that are in need of adjustment.

Next, you go speed density like normal (kill the MAF with Fail Frequency). Using your new IFR table, dial in the VE table. Once you're done, you should be able to re-enable the MAF, restore B0120 to stock or there abouts, and not have your fuel trims sky rocket like everyone always does.

Why do it this way? Personally, I'd much rather adjust the handful of IFR cells rather than the 84 MAF cells. Plus, I find it hard to believe that a cam & heads can drastically alter the MAF cal. You put the stock lid and bellow in and you'll still have to adjust the MAF curve with the other way. That to me says something is fishy and something is being fudged. So, fudge the MAF or the IFR??? I say fudge the IFR. Too many other tables rely on what the MAF reports (timing, trans pressures, etc.). That should stay stock IMO.

Have you tried this method with an complete aftermarket air intake and LS7 style MAF meter?

[redhardsupra]

SSpdDmon, let me get this straight: you entire argument about the superiority of the IFR fudging method over others is that it's simpler?
MAF isnt really 84 cells, it's more like 4 parameters describing the polynomial that creates the curve. IFR however is usually a lot more nonlinear than that, as you have voltage dropping affecting fuel pump output (a nonlinear relationship by itself), affecting the rail pressure, and then there's another nonlinear dependency of pressure delta vs IFR... if your argument is purely from simplicity, MAF wins by a long shot.

[SSpdDmon]

Have you tried this method with an complete aftermarket air intake and LS7 style MAF meter?

Only on my LS1s.

SSpdDmon, let me get this straight: you entire argument about the superiority of the IFR fudging method over others is that it's simpler?
MAF isnt really 84 cells, it's more like 4 parameters describing the polynomial that creates the curve. IFR however is usually a lot more nonlinear than that, as you have voltage dropping affecting fuel pump output (a nonlinear relationship by itself), affecting the rail pressure, and then there's another nonlinear dependency of pressure delta vs IFR... if your argument is purely from simplicity, MAF wins by a long shot.

I beg to differ. With the stock MAF curve, you'll see your voltage drop in your IFR because it won't be linear near 0kPa of manvac. If you have a car with a fresh h/c swap and start it up, it won't idle very well at all. A minor change to the base timing and changing B0120 - it idles right away. If that's not simple, I don't know what is. Trying to adjust 84 MAF cells via BENs vs 16 IFR cells, I pick 16. Also, as mentioned above, think of the effects of changing the MAF curve on things like your timing table. You essentially shift the table to the left by increasing the MAF. Stock curve may show .8 grams/cyl and adjusted curve .88 grams/cyl - you've now pushed the high/low timing lookup to a lesser value. Don't the A4 cars also use MAF readings??? I don't believe a 15~20% change in the MAF curve is right by any means. But, that's my choice to believe that...and I'm not here to dis-credit anything. Just saying this is another approach I took to skin the cat.

[TAQuickness]

$0.02

I like the creativity of SSpdDmon's approach and the fact he has consistent results with this method. I don't know that it will change my ways*, but do think it warrants a comparitive test drive.

* This is largly in part to the MAF not being able to compensate for changes in the induction plumbing. Given the installation environment, the MAF is not nearly as accurate as it is consistent.

[jfpilla]

SSpdDmon,
I do respect your right to tune as you see fit, so I'm not trying to change your mind, just want to share my observations.
I don't see a voltage drop when I scan WOT into an IPW voltage table.
I like the extra resolution of tuning the MAF and I see other parameters logged showing closer trims. The MAF is really not hard to tune and you need to tune upper frequencies to get WOT PE to match actual. Timing tables are useless and need retuning anyway. A4's use B5919 not the MAF for calculations except for 98's and 99's? If you have an optimal timing table it's used. It seems more fueling dependent tables are affected by IFR changes. I don't find that setting the MAF requires any other changes.
It seems that same injectors in different cars use the same tables?
My engine is an LS7 with longtubes and cold air. It's otherwise stock. The IFR is stock LS7. Seems the right thing to do. The stock MAF table does not work.
Joe

[SSpdDmon]

SSpdDmon,
I do respect your right to tune as you see fit, so I'm not trying to change your mind, just want to share my observations.
I don't see a voltage drop when I scan WOT into an IPW voltage table.
I like the extra resolution of tuning the MAF and I see other parameters logged showing closer trims. The MAF is really not hard to tune and you need to tune upper frequencies to get WOT PE to match actual. Timing tables are useless and need retuning anyway. A4's use B5919 not the MAF for calculations except for 98's and 99's? If you have an optimal timing table it's used. It seems more fueling dependent tables are affected by IFR changes. I don't find that setting the MAF requires any other changes.
It seems that same injectors in different cars use the same tables?
My engine is an LS7 with longtubes and cold air. It's otherwise stock. The IFR is stock LS7. Seems the right thing to do. The stock MAF table does not work.
Joe

I agree - there's some good resolution to fine tuning the MAF to dial in fuel trims. What I'm trying to avoid is massive changes. I think if you're changing it more than 5% or so, something doesn't seem right. I'm merely suggesting you get the IFR dialed in so, for the most part, commanded=actual. Then, any fine tuning you need to do afterwards shouldn't require anything major.

Oh well...I'll keep experimenting. It's fun...

[TAQuickness]

Oh well...I'll keep experimenting. It's fun...

No doubt! I'm curious to see the results I can derive utilizing this methodology.

For someone starting from scratch (bone stock) that is planning a build of any sort, I can see a slight variation of this method providing the means to backcheck/verify calculated injector settings. I seem to recall Geoff @ thunder describing a similar method to derive injector settings.