FiTech tuning for trails and rock crawling.

[73azbronco]

well... shit.

I was thinking it was a good idea to try and keep the throttle body cool...

anyone want a nice dual plane intake?

You can use a phenolic spacer and or aluminum plate to keep it cool. I would not worry about those until its running like you want it. I think torker II is best bet.

 

[RADO]

Hinmaton, it might be worth posting your current fitech settings and I can compare them to mine. I take the Bronco 4 wheeling often and can't really relate to the issue your having. I have a crawl ratio issue, being at 46 the Bronco moves too fast for rock crawling. But I don't notice the engine RPM jumping or feeling uncomfortable with throttle being too touchy. I have a dual plane intake, stock throttle linkage, and an AX15. I don't use my fitech for timing control though.

 

[KyleQ]

Next time your out on trail in low, crawl along at an idle, engage your brake enough to slow your forward progress (note your rpm) then let off the pedal. Does the rpm stay the same or rise?

Hinmaton

I'll give that a go today after work in the back yard - I think my RPM will rise back up but that is going to be due to idle speed and my tallish gear ratio.

If I can get my handheld working I'll grab a few snaps of my settings as well-

 

[Hinmaton]

I can do that-
I have a 60:1 final drive, so it crawls alright.
I might be a bit over sensitive as well : )
I’m used to crawling with an automagic and it’s really easy to be slow, steady and smooth, and then ease into the power when you need it.
With a manual, unless you’re slipping the clutch it’s more Go/NoGo.
But here are my settings for the most part. I dropped my idle to 800.

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[Hinmaton]

The idle loop rates up and down plus the decel open IAC are the main targets to regaining engine breaking and stopping the idle from ramping up after a stop or slowing down.
Interesting that you haven’t noticed. The system is designed to do this out of the box, as explained to me by Bryce and Cody at FiTech.
Try revving your engine in neutral then let of the gas quick. Time how long it takes to get back to target idle, including the undershoot.
Then try it under load.

Hinmaton


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[KyleQ]

Mine is slow to idle down and is my biggest annoyance with the system. Haven't cared enough to go after it, but if the info is there I'll mess with it.

 

[Hinmaton]

Mine is slow to idle down and is my biggest annoyance with the system. Haven't cared enough to go after it, but if the info is there I'll mess with it.

Change your loop rate down to around 15-20, you will see a difference.

Hinmaton


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[KyleQ]

Thanks - I'll record it.

 

[RADO]

The idle loop rates up and down plus the decel open IAC are the main targets to regaining engine breaking and stopping the idle from ramping up after a stop or slowing down.
Interesting that you haven’t noticed. The system is designed to do this out of the box, as explained to me by Bryce and Cody at FiTech.
Try revving your engine in neutral then let of the gas quick. Time how long it takes to get back to target idle, including the undershoot.
Then try it under load.

Hinmaton


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Your settings are generally quite different from mine, which will make it harder to track down any key differences. I also don't know if a 351 vs 302 would make a difference in the throttle response. I would assume the idle control would act the same between engines.

Loop Rate UP: 25
Loop Rate DOWN: 15
Decel Open IAC: 14.1
* I'll check a few other settings when I 'm home


I'll play around with my Bronco this weekend to check the idle/crawl behavior and report back.

 

[Hinmaton]

Your settings are generally quite different from mine, which will make it harder to track down any key differences. I also don't know if a 351 vs 302 would make a difference in the throttle response. I would assume the idle control would act the same between engines.



Loop Rate UP: 25

Loop Rate DOWN: 15

Decel Open IAC: 14.1

* I'll check a few other settings when I 'm home





I'll play around with my Bronco this weekend to check the idle/crawl behavior and report back.

I think that the 351vs302 shouldn’t have a huge effect.
I haven’t touched a lot of those settings, mostly the Timing and Idle Control, maybe a little cranking to work out cold and hot starts.

Hinmaton


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[PaveBronco]

Viperwolf did a writeup on his progressive throttle design using a couple of parts from Home Depot for something like $10, but, I've searched around and cant find it. funny thing is I was going through a build thread yesterday and they did the mod, with nice pics, but...again cant remember which one.

 

[Hinmaton]

Viperwolf did a writeup on his progressive throttle design using a couple of parts from Home Depot for something like $10, but, I've searched around and cant find it. funny thing is I was going through a build thread yesterday and they did the mod, with nice pics, but...again cant remember which one.

Dang! I would like to see that.


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[WheelHorse]

What's the base timing at?

What's the mechanical timing advance to and when does it start adding?

What's vacuum timing at: how much and when?

MY thought is a little backwoods, but why not simply disconnect and plug the vacuum advance before hitting the trails. The on/off vacuum advance with the application of the throttle, if you are running port, by eliminating it, may help with snappiness.

If you had a full control system...i.e. electronic t-body and full timing control, this would be easy to tune.

Otherwise you could study this and try to adapt something of your own:

Speedway progressive Carb linkage

Otherwise you could try to adapt something similiar to what was previously mentioned by Viperwolf.

Progressive t-body set up for Ford EFI

 

[DirtDonk]

Dang! I would like to see that.

Glad he brought it up too. Haven't read it in awhile and would like to see if it would work on my Explorer setup.

It's not going to be the same for a FiTech or other TBI setup since it's designed for the stock Ford EFI stuff. But the concept is valid for just about anything.
The TBI units just don't tend to suffer the same issue, so not as needed.

Paul

 

[DirtDonk]

Thanks for the link WheelHorse.
Going to try to memorize it now...;D

Paul

 

[RADO]

The idle loop rates up and down plus the decel open IAC are the main targets to regaining engine breaking and stopping the idle from ramping up after a stop or slowing down.
Interesting that you haven’t noticed. The system is designed to do this out of the box, as explained to me by Bryce and Cody at FiTech.
Try revving your engine in neutral then let of the gas quick. Time how long it takes to get back to target idle, including the undershoot.
Then try it under load.

Hinmaton


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I performed this test over the weekend and saw a slight difference "idle to 2500 RPM to idle" comparing neutral vs gear. Its about 6 seconds for my unit to return to idle in gear. It's a pretty slow return and tuned this slow on purpose because I was originally having an issue with the RPMs crashing out and stalling the engine. In low gear, braking will speed up the engine RPM drop.

The engine maintains the idle setpoint (800 RPMs) when in low gear and 0% throttle position. It maintains the RPM pretty smoothly and doesn't jump around much. I also don't have any issue with the engine RPM increasing downhill uncontrollably. I've used downhill engine braking quite a bit on harder trails. I tested all of these things last weekend to confirm the behavior.

Some more fitech settings:
Decel RPM decay: 6.7
Decel IAC decay 0.5
dTPS ACC Gain: 109 (same as yours)
dTPS Acc Max: 144.5

Lastly, my pedal doesn't feel super snappy. I remember it was a bit more reactive when I first installed the Fitech and I may have tuned some of the throttle pep out of the unit (could be my imagination too). I use the stock throttle linkage and added a return spring. This gives the pedal a heavier feel.

I wish I was more help in pin-pointing the corrections. I wanted to at least confirm that your unit can handle better off road than it currently does. My fitech works phenomenal off road for performance and control. I would just keep playing with the Fitech settings and throttle linkage until you notice a positive difference.

 

[Hinmaton]

Thanks RADO.
I’ll try those settings and see.

Hinmaton


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[Hinmaton]

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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[73azbronco]

Are you sure the throttle/pedal/linkage/butterfly is actually closing when it does this?

 

[Hinmaton]

Are you sure the throttle/pedal/linkage/butterfly is actually closing when it does this?

I’d be lying if I said I knew for sure, I haven’t looked down the throat while attempting. But I feel confident that it is closing. It’s not like a hung carb that will drop closed if you tickle the pedal enough.
It maintains if not slightly drops and then raises maintains and drops. When I tried to describe it to FiTech, Bryce finished my sentence and said that’s the way it’s designed, and if it really bothered me it could be changed. I left it alone, as I’d only been running the unit for a month. Figured it was something I’d get used to? And until I noticed it crawling, it doesn’t really effect much of anything.
I’m guessing it’s an attribute similar to the initial start up rpm increase. Hot or cold, it raises above idle for a cycle. At least on mine.
190 degrees hot start, just crank it and not wait for the prime shot. It starts right up, the idle climbs to a grand or so and sits for maybe 6-10 seconds and then drops back down.
Heck even my ‘15 JKU does this on hot starts.
I’m guessing it’s a manifold wetness thing?

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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