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ECUflash Injector latency values

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Latency = deadtime= injector on time

more latency would = a larger amount of time to fully open & close

edit-had it backwards- fixed
 
Last edited:
Latency = deadtime

more latency would = less fuel kinda ( a larger amount of time to fully open)
Ok that's what I had thought. I seen another post that mentioned more latency = more fuel. I knew that couldn't be correct, startup idle AFR is good on my car 14.7, but after driving a bit the idle stays around 12ish. I doubt adding more latency would change that.
 
Latency (or deadtime) is the response time that it takes an injector to open after it is energized. It makes a bigger difference the bigger the injector flow rate is. Usually, in most tuning software, adding or increasing deadtime values adds time to the pulse width of every injection event, thus increasing the amount of fuel delivered.
 
Bigger latency in the tune equals more fuel, less equals less, the software does the calculations, but technically its bigger latency the injector will put out less at a given pulsewidth.
 
How about the MAF smoothing table? It seems pretty straight forward, left side is the MAF HZ and right side is the fuel % to give less fuel at say 100 HZ I would lower the % column? It seemed to do the exact opposite and give me more fuel with a lower % number.
 
The MAF smoothing table is to correct airflow measurement errors made by the sensor. Like if you have a slightly troublesome spot where the engine goes lean momentarily every time you cross that one certain MAF frequency.

What you're doing by changing the percentage column is telling the ECU to now use this percentage of the hardcoded airflow value for that frequency point. So if you tell it to use 95% at 300hz, it will look up the value in the table at 300hz and then multiply that airflow value by 0.95 and use that instead. It changes fueling more precisely because you're changing reported airflow instead. If target AFR is 10:1 at that spot and you change reported airflow by 10%, the fueling changes 1%.
 
Let me try a different way. (not counting posting overlap) As others have stated the injector latency is "deadtime" the amount of time spent waiting for the injector to start spraying fuel after it gets a signal to do so, minus the time it takes the injector to stop spraying fuel after you tell it to stop. The ECU normally calculates from air mass flow how much fuel it needs and knowing the injector flow rates it derives an injector pulse width to which it has to add the latency so that the time actually spraying fuel equals the expected pulse width. Since latency is fixed but injector pulse width isn't the latency value has more % effect on low iPW that on high ones. (More effect at idle than WOT)

If you guess wrong and make the latency too small you with up getting less fuel than desired and if you go the other way and use a too large value the result it the injector are open longer than desired and you get a richer ratio.

MAF smoothing is intended to linearize the MAF signal with regards to the airflow. Since all fueling calculations start with the mass airflow you want the measurements to be as accurate and linear as possible. IMO, Unless you changed the MAF or modified it and have a way to calibrate it you may be messing with the wrong table for tuning the car.
 
Let me try a different way. (not counting posting overlap) As others have stated the injector latency is "deadtime" the amount of time spent waiting for the injector to start spraying fuel after it gets a signal to do so, minus the time it takes the injector to stop spraying fuel after you tell it to stop. The ECU normally calculates from air mass flow how much fuel it needs and knowing the injector flow rates it derives an injector pulse width to which it has to add the latency so that the time actually spraying fuel equals the expected pulse width. Since latency is fixed but injector pulse width isn't the latency value has more % effect on low iPW that on high ones. (More effect at idle than WOT)

If you guess wrong and make the latency too small you with up getting less fuel than desired and if you go the other way and use a too large value the result it the injector are open longer than desired and you get a richer ratio.

MAF smoothing is intended to linearize the MAF signal with regards to the airflow. Since all fueling calculations start with the mass airflow you want the measurements to be as accurate and linear as possible. IMO, Unless you changed the MAF or modified it and have a way to calibrate it you may be messing with the wrong table for tuning the car.

So my idle and WOT are almost perfect. Cruising is the one that is way to rich. On ceddy website for injector tuning it says that maf smoothing is to tune cruising afr.
 
So how do your AFR's match up to your fuel maps?
Seems to be a little richer. I dont have a way to log my wideband but based on looking at it and comparing to the afrmap its richer at cruising rpm. It's also a custom big map that English racing tuned when the previous owner had the car.

I've added a fp intake pipe, fp exhaust manifold, and 16g turbo since. Old turbo was a 14b
 
With flash you will use MAF smoothing to dial in your air fuel calibration

Works basically like any AFC, you alter reported airflow from the MAF and the ecu will do the calculations to apply the correct fueling for the reported airflow

In closed loop the ecu is always going to use O2 feedback to adjust the fuel trims as needed for stoich. You really don't want to try and fight what the ECU is trying to do during closed loop operation. If the ECU makes big fuel trim adjustments you need to adjust as needed to bring the trims back in line.

So when adjusting MAF smoothing it's easiest to do so while in open loop while logging AFRmap and wideband O2 feedback, both scaled the same and overlayed to see the differences

The deadtime has the biggest impact during low injector PW operation, idle and lower rpm. Since the injectors have such a short pulse at idle if the injector takes longer than what the PW applied by the ecu you would get little to no fuel during that cycle. Deadtime gives the ecu an amount of time extra it needs to allow for the injector to actually fire and start delivering fuel.
 
Thanks for all the awesome replies guys. This would be so much easier with link but ecuflash is all I have right now. I'll get some good logs of cruising on the way home from work in the morning and hopefully get it all straightened out.
 
Warm up idle and cruise home, most of the time I was cruising around 2-2.5k RPM in 4th and 5th gear. I did do a couple harder accelerations. Cold start my AFR was between 14.8-15.2 after the car warmed up it still stayed at that. I drove out of the parking lot AFR was 13.3 then before getting on the road it dropped to 11.9 then my idle was 12.5 at the red light. Rest of the cruise home my AFR was around 11 and sometimes would even go lower 10.6 on light throttle. my WOT would read fine at 10.7. Never seen the 14.8 idle again though.
 

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