What controls the injector pulse width at WOT?

From what I recall on my old GT, the closed loop operation looked at a bunch of junk, but WOT looked only at a hardcoded fuel table.

My 94 Cobra, on the other hand, used load based calculations even at WOT for fuel delivery calculations.

How does the L do it - ABU2 ECM in particular? I am starting to analyze some data and I want to know all I can about what affect the fuel at WOT.

I datalogged three runs last night and overlayed the plots of RPM and AF ratio. The RPMS look like the same plot and all three have a jog in the slope 1/2 way through 2nd gear.

The AF ratio plots are real close as well, but they all have some strange blips toward the lean side at the same point in the curve. All three runs did not drop below 13:1 in first gear until over 5000 rpm! Second gear had more time above 12.5:1 than I'd like, but it dropped at the jog in the RPM each time. I did not see less than 12:1 until 1/2 way through third gear.

The air last night gave a DA of 1076 ft. with 63 degrees, 88% humidity, 59 degree dewpoint and 30.05 bp. Track is at 600 ft and I was pulling 4920 lbs.

Thanks,
Herb

 

Same way I think ... It ignores all input other than the fuel table.

It does wait a peroid of SECONDS to decide to go to the tables though.

 

Thanks Cliff,

That may help explain my scary O2 readings in first gear. It was like 13:1 all the way through 1st!

Anyon else have any details to add about how the fuel is controlled and what triggers the adders?

I'm thinking seriously about the SCT Pro Racer and Raptor, but I'd like to see what the Sniper has to offer.

Thanks,
Herb
(damn - still in the 13's)

 

Oh how familiar that statement is ... LOL ... Don't give up, Herb,
it will come ...

 

Anyone else have any details about how this works?

Thanks,
Herb

 

From all the reading I've done, I haven't come across a solid description of how the ECM controls the fuel, timing, etc. at WOT.

I too would like to know what factors affect timing (I.E. does a high IAT2 pull timing at WOT?), fuel delivery, etc.

Are there any tuners on here that would care to give us a good idea of how our fuel, timing, etc is controlled in a WOT condition?

 

The computer takes MAF voltage/load and uses a preset A/F value per the RPM. For injectors it is all values in the programming, and it adjusts depending on battery voltage/temperature. For timing it takes a timing table and uses temperature/gear/rpm for timing. It's all pretty simple actually.

 

I was hoping you'd chime in on this one Casey. How much of that set of equations is alterable with the SCT Pro Racer software? I am seriously considering that package, but know little about it currently.

Do you know how the ECM calculates load? I would imagine that vacuum/boost would be an excent indicator of load, but I don't think the L's ECM uses a BAP sensor for load. My old 94 Cobra calculated load, but I don't recall the specifics.

Also. is that vMAF/load a descrete value, or is that in a table? I seem to recall playing with non-linear transfer tables with MAFs in the 94 with the Shiftmaster EECTuner.

Thanks,
Herb

 

ttt