How to tune Fitech lean to rich spot? - Chevelle Tech
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post #1 of 14 (permalink) Old Mar 5th, 19, 2:32 PM Thread Starter
 
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How to tune Fitech lean to rich spot?

Hi all
New member but an old time reader to this forum.
Don't have a Chevelle but do have a sbc 350 with Fitech 600 power adder installed in a 1983 full size Jimmy.
Located an ocean away from Detroit but love the feel of an old V8.

Well, enough about me.

I built my truck over 8 years period, and now it's time to finally tune my Fitech.

I need your guys help with what parameters I should change to solve 2 problems:
1. Get rid of the rich spot I get (mostly comes after a momentary lean spot)
2. Get rid of the lean spot at idle (while deaccelerating)

I'm attaching a few screen captures of a log from a drive I did yesterday.

Please ask questions, will try to answer them all.
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post #2 of 14 (permalink) Old Mar 5th, 19, 4:42 PM
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Ken
 
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Re: How to tune Fitech lean to rich spot?

You might try this site:
https://fitechefituning.com/

Look through the existing posts, or post your question. Austin, who runs the site is usually quick to answer.

67 Chevelle Malibu, ZZ4 350 crate engine, TH350, FiTech EFI, Vintage Air, Dakota HDX dash, FlowMaster exhaust,
17" Rally style wheels, Redline tires
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post #3 of 14 (permalink) Old Mar 5th, 19, 4:46 PM
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Justin
 
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I don’t have a fitech I have a sniper, but I agree with the above that the best thing you can do if get on a fitech specific forum and ask for help there. I get my Holley sniper help from the Holley forums and it’s great

1974 chevelle with 73 laguna nose sbc 357 Brodix IK180 heads Comp Cams XE274H Edelbrock RPM airgap 650 AED double pumper, M20 muncie, Truetrac with 3.73s
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post #4 of 14 (permalink) Old Mar 5th, 19, 5:00 PM Thread Starter
 
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Quote:
Originally Posted by darksky View Post
You might try this site:
https://fitechefituning.com/

Look through the existing posts, or post your question. Austin, who runs the site is usually quick to answer.
Thanks I'll try to post there
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post #5 of 14 (permalink) Old Mar 5th, 19, 5:52 PM
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Steve
 
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Re: How to tune Fitech lean to rich spot?

Lean to rich bog can be addressed with 4 parameters in the Accel Pump menu in the Go EFI Pro Tuning menus. The fix is counterintuitive. Don't dwell on it.

Accel Pump for typical easing into it throttle use
Fast Accel for quick throttle use, like WOT from a stop, or quick half throttle from a stop, or both of those while cruising.
dTPS Acc Gain for a general gain in fuel used
dTPS Acc Max to limit the maximum gain

I'll give you some numbers to play with. You may have to back off on them depending on your intake, heads, and exhaust. If you don't notice any change with the numbers I'm providing, you have other problems that need to be addressed. BTW, you can band aid it doing exactly the opposite of what I'm suggesting by pulling fuel, but your motor won't make as much power. I've done it both ways. More Accel pump works best when the numbers are right. You are trying to kill the lean tip in, which is what causes the over rich correction.

Plug in these numbers.

Accel Pump 20F 11.7
Accel Pump 65F 25
Accel Pump 170F 55.5

Fast Accel 20F 13.3
Fast Accel 65F 25
Fast Accel 170F 59.4

dTPS Acc Gain 147.7
dTPS Acc Max 151.6

Don't lean your Idle AFR out too much. Stoich for pump gas with 10% Ethanol is an AFR of 14.08. Stoich for straight gas is an AFR of 14.68. My motor likes 13.6, but it breaths funny.

For ultra fine tuning you can modify the duration of the pump shot with the Accel Decay and Fast Decay parameters.
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post #6 of 14 (permalink) Old Mar 5th, 19, 6:13 PM
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Chris
 
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Re: How to tune Fitech lean to rich spot?

you may find this helpful.

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post #7 of 14 (permalink) Old Mar 5th, 19, 6:35 PM
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Steve
 
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Re: How to tune Fitech lean to rich spot?

Chris
That video is helpful for anyone getting started with the joys of FiTech tuning. Cool to see someone taking the time to describe the typical things that need to be addressed if the system doesn't work out of the box.

Limiting Fuel Trim Max in the AFR Closed Loop section is important. I forgot about it.

Thanks for the reminder

'65 Chev El Camino
350/400+HP, 700R4
Edelbrock Pro-Flo 4 MPFI
Global West, QA1, Viking, Wilwood, UMI, ProForged
'68 P-11 Norton
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post #8 of 14 (permalink) Old Mar 6th, 19, 8:39 AM
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Todd
 
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Re: How to tune Fitech lean to rich spot?

From the data logging it looks like your fuel pump is faulty or the fuel pump wire from the system has a bare spot. Do you have a FP gauge on the inlet to watch as you manually rev the motor to see if it spikes hard or if it might be dancing around at idle?
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post #9 of 14 (permalink) Old Mar 6th, 19, 11:08 AM Thread Starter
 
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Thanks for all the good advices, I will try them on Friday morning and let you know how it went.

Regarding the fuel pressure gauge, No, I don't have one.
When I was running carb I used to have but that was for low pressure.
The pump in the fuel tank is new and should be fine (if wiring really is ok)
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post #10 of 14 (permalink) Old Mar 6th, 19, 2:42 PM
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Todd
 
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Re: How to tune Fitech lean to rich spot?

The first walbro pump I installed with the system was faulty out of the box and it took me a while to figure it out with a gauge on the inlet. It should hold a steady 58psi of fuel pressure at the gauge and go up as needed.
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post #11 of 14 (permalink) Old Mar 6th, 19, 3:19 PM Thread Starter
 
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I'm using the Holley In-Tank RetroFit Fuel Module-Returnless Style with the Hydramat, same as in this link:

https://www.holley.com/products/fuel...e/parts/12-131
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post #12 of 14 (permalink) Old Mar 8th, 19, 4:29 AM Thread Starter
 
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Went for drive
Changed one parameter at a time and logged the ride (10 different logs in total).
Honestly, I don't think any of the changes I did had made any improvement.

I'm starting to give up...
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post #13 of 14 (permalink) Old Mar 8th, 19, 8:23 AM
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Todd
 
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Re: How to tune Fitech lean to rich spot?

Been there and done it man! It does suck when the system won't cooperate. I do know that the system needs a constant 58 psi at idle with no fluctuating. A good tach signal and some good grounds. I got to a point that I just drove it the way it was for a few years. Then when I swapped the auto out for a manual the system went crazy and would not cooperate. I ended up removing it and putting the carb back on and sold the fitech. The carb works better for me. I had the base 400 horse system as well. I wouldn't give up just yet. The giant thread here has alot of good tips to hopefully get your system straightened out.
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post #14 of 14 (permalink) Old Mar 8th, 19, 11:35 AM
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Steve
 
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Re: How to tune Fitech lean to rich spot?

The default numbers for the parameters are in the default V8 calibration file in case you need to write the calibration to the ECU to change back to the defaults before you put it up for sale.

Both the FiTech Go EFI 4 600HP and Go Port systems work for me, and I'm not shy about changing parameter values in mass like a lot of people are. I know what the parameters do though, which is why I made the bold suggestions. Those numbers work for me, but every motor configuration responds differently to the tune.

Most likely there is something off with your install, if you can't make it work. For example, intake leaks, exhaust leaks near the O2 sensor, poor electrical system, failing ignition parts, wrong cam profile, clogged fuel filters, bad or incorrect fuel pump, poor condition of the engine, and the list goes on. A carburetor will run on just about anything. EFI not so much.

'65 Chev El Camino
350/400+HP, 700R4
Edelbrock Pro-Flo 4 MPFI
Global West, QA1, Viking, Wilwood, UMI, ProForged
'68 P-11 Norton
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