FiTech tuning for trails and rock crawling.

[RADO]

I stuck it in there and drove it a bit, but until I get it on the trail it’s hard to say. Next weekend maybe.
But on the other hand, fooling around with it, I remembered what it was doing that I didn’t like.
And please test this and let me know. Should matter what transmission.
While at a stop light or similar, with engine at temp and idling. Press the accelerator ever so slightly, move the rpm maybe 100 and let off.
Does it drop or continue to climb?
Mine- if I bring it from idle 850 to 950 and let off, it will hold the 950 for a fraction and then climb up to 1100 / 1200 hold it for a fraction and then drop back to idle.
This is the behavior I was trying to recall and relay. It does it while idling in gear crawling too.

Hinmaton


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Hmmm, is this the Fitech IAC opening when you close the throttle? Under 1000 RPM, my engine will just return to idle after bliping the throttle. If I blip the throttle to somewhere like 1200 RPM, the RPM will start to drop quickly but catches itself, adds ~100 RPM and then slowly returns to idle. I didn't see the RPM increase over the initial RPM spike during the return to idle. I would look at Decel Open IAC, Decel IAC Decay &/or Decel RPM Decay. Also make sure your IAC is set 3-10 at warm idle.

 

[Hinmaton]

I’ll check the IAC steps when it’s doing this.
My idle IAC has been a pretty consistent 5-6 every time I have checked.


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[Hinmaton]

well heck if I know...
Here's a video of it:
https://www.facebook.com/Hinmaton/videos/10217030110727808/

The strange thing is, I think the rpm is increasing as the IAC steps are decreasing? Vacuum looks good. I don't know how to read MAP yet.
You can also see I am just feathering the accelerator, just moving it up and pulling my foot away.

Hinmaton

 

[73azbronco]

From FiTech
“ Intake manifolds are going to get wet with fuel while running. This wetness changes with temperature, engine vacuum, and air flow speeds. This wetness also must be supplied in addition to the fuel that is intended to reach the cylinders. This wet film of fuel on the surface is much thicker at cold engine (fuel doesn’t evaporate well when cold), and also varies greatly with vacuum (bigger at high loads, smaller at low loads). The software has a strategy to supply that fuel and compensate for the changing size of the film. However, different manifolds have different characteristics, so some adjustments may be necessary to give the proper fuel during a “transient” event (transient is a term used to describe moving the throttle and changing the load). The fuel added during a transient has to be added in a special way to cause the wetness to build correctly over several injections. It starts out large, and decays to 0. The decay adjustments shape that curve. A larger decay value causes the accel “pump” amount to be ended sooner, and a smaller decay value allows the fuel to extend a little longer. It’s a fine art of calibration to get this perfect, requiring a super-fast reading of a lambda sensor. It’s recommended to only adjust these values when you notice it’s a problem. It also shouldn’t be adjusted much until the fuel learning has had plenty of time to adapt to the engine. The Accel fuel calculation uses 2 different signals that work mostly independently determine how much fuel to add/subtract. The MAP is directly used for “Accel Pump” fuel. The Alpha-N MAP is used for the “Fast Accel” fuel. Alpha-N uses the TPS and RPM to calculate a secondary “MAP” signal in case of the MAP fault. That value is also used to calculate the “Fast Accel” fuel, because it responds slightly faster than the real MAP signal. “

Hinmaton


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I read this tech tip from fitech as, "we have not figured out how to properly deliver the fuel to the engine yet, but someday maybe. Until then, there will be issues we can't control".

 

[Hinmaton]

I read this tech tip from fitech as, "we have not figured out how to properly deliver the fuel to the engine yet, but someday maybe. Until then, there will be issues we can't control".

Funny, that’s what I get as well.


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[KyleQ]

What do you expect from TBI - we wanted affordable injection, not magic.

 

[Hinmaton]

What do you expect from TBI - we wanted affordable injection, not magic.

Well put. I actually had no idea what to expect. Other than maybe easier starts in colder weather. This thread was more about tuning the TBI for trail use, than anything else.


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[KyleQ]

Yeah - for me, and what I do, it runs excellent. I run on cam setting 3, only adjusted my target AFR's and I haven't had my handheld in the truck since.

 

[Hinmaton]

Now that’s interesting.
Why cam 3?
I went with cam 1 simply because I have my vacuum is at -20 at idle.


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[RADO]

Now that’s interesting.
Why cam 3?
I went with cam 1 simply because I have my vacuum is at -20 at idle.


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I think you have it set right. My cam setting is 2 and my vacuum is around -14 idle.