What should the short term fuel trim be on e85? The reason I'm asking is because my stft is %20 at idle. The only way I can lower it is by lowering the injector scaling. Should I just be concerned with LTFT?

 

Figured it out- nevermind.

 

These latency figures were posted JBradley in another post for FIC 1000 and he said he had great success with these figures. Kudos to JB.
3.312
1.68
1.344
1.152
0.84
0.504
0.24
The scaling was set to 860. Now the question is do the latencies change when using E85? Would I have to do 30% of all those numbers to get the correct latencies? I have my scaling set to 585. I believed after reading the above scaling that I should change my scaling to around 602.

 

Keep latencies the same and see how it goes man. Theoretically it's just injector dead time, it does not depend on the fuel. That's not to say you wouldn't have to fine tune it anyway for your exact set-up. So plug those in, adjust scaling, fine tune latencies by looking at your LTFT trims and STFT feedback.

Another thing to keep in mind with E85, even if you tune LTFT trims to 0's, blends change often and your trims will drift away and that's ok, so long as they are within +/-10 or so (on +/-25 scale) your driveability shouldn't suffer.

 

Does raising the number(numerically) of the latency make the car run richer or leaner at 14v? So I should set my scaling to 600ish and leave the 93oct latencies?

 

Raising latency makes the car run richer.
Lowering scaling makes the car run richer.

 

Also when it comes to scaling what you're really trying to achive is just running the same kind of AFR's as with stock injectors with your fuel maps as you did before.

Meaning for example if your fuel map says 9.0AFR in 6000rpm and 280 load and you saw 11.5 AFR on old injectors, scaling allows you to achieve the same numbers with new injectors. Otherwise you can just adjust the fuel map, that's all.
So 600 works, 580ish as well. I think mine are 609, where i set them almost 2 years ago.


And when it comes to latencies they are more important for idle where IPW are small, especially with big injectors. That's why when you adjust latencies higher or lower, you try to bring your idle LTFT closer to cruise LTFT.

 

Cool- thanks for the info. I flashed JB's latencies in and tweaked the 14v to get my short trim to +2. When tweaking latencies do you just mess with the 14v or do you do an accumulation between 11-16v? With those latencies installed my car fired up on the first crank of the day (40* outside). I have my injectors scaled to 585 and my 14v latency at .792 and it gave me those above mentioned fuel trims. Haven't checked long term yet but I'm sure it will be really good.
To sum up your eplanation, scaling has more impact on ltft and latency has more impact on stft and the IPW adder is obviously for startup. Which fuel trim logging software is the most accurate- mitsulogger, evoscan, scantech?

 

Do you have a wideband? If car idles near the target 14.7 without jumping all over then you trims and scaling are close also. i guess this is similar to watching the o2 feedback.

If you gas trims were at a comfortable level you should only have to lower your scaling for e85 by approx. 30% or to where trims are near same as gas.

when I switched from e85 to gas or vice versa I was 636 (e85) and 840 (91 gas)
I believe but my latencies were greater than what you are listing for FIC 1000's

 

I don't have a wideband yet so I'm currently going off logging software. Evoscan and Mitsulogger are putting out the same results with my fuel trims- +5 idle and -4 cruising. Don't have a long term yet. With Scantech my trims are +2 for idle and cruise. Which is more accurate(software) and what steps should I take to get the idle down to 0 and cruising up to 0? One more annoyance- I can't get evoscan 2.5 to read tq or hp. I'm not to concerned about it but it would be nice to have for logging. One more note- I have my cruising and idle AFR on the octane maps set to 15.1. Are you only adjusting the 14v or are you adjusting the 11v and 16v also?

 

First of all, I think you have a slight misunderstanding of fuel trims, short term and long term.

STFT (or o2 feedback as some call it), is the trim that is rapidly adjusting your fuel to hit a stoich 14.7:1 at idle or cruise. There are three long term fuel trims (LTFT), LTFT Lo, LTFT Mid, and LTFT High. (BTW, you 15.1 in your fuel maps is doing nothing, unless you are running open loop in those areas...change it back to 14.7)

LTFT Lo is for lower airflows, such as idle
LTFT Mid is for airflow levels during situation such as cruise
LTFT Hi is for airflow levels that you probably won't reach during cruise

So, to get a real picture of your fuel trims, you need to log the following:

1. Idle - log STFT and LTFT Lo
2. Cruise - log STFT and LTFT Mid

The STFT will be bouncing around a lot, but you will be able to see what number it is bouncing around. Eventually, if you idle and/or cruise long enough, any non-zero averaging STFT will move in to the repsective LTFT (lo or mid). So, evetually, your STFT will be bouncing around 0 and the LTFT will have the full correction.

If you don't want to wait that long, just add the two values and you will see how much your fueling is being corrected by the ECU. For example, if at idle your STFT is bouncing around +4 and your LTFT Low at that same time is +5, then your total correction is +9. Eventually, your LTFT low will be +9 and your STFT at idle will be bouncing around 0.

Aso, regarding latency, you should change all of your latency values when adjusting them. The latency values are just a curve representing the reaction time of your injectors with respect to voltage. You don't just change the 14v cell. You may never hit some of the other cells, but it's good to keep the original shape of the curve.

So, if you could log what was asked, we could give a better answer on what you should do. It doesn't matter what tool you use to log as long as they are setup properly and you know what you are logging. EvoScan or Mitsulogger would be easiest. Some versions of EvoScan have the wrong requests for the fuel trims and the wrong forumla for the scaling. So, if you are using EvoScan, do a search first for the correct entries. I know I have posted many times on the subject and how to scale your injectors.