1. Join the Community!

    DSMtuners is a massive archive of DSM information - but more importantly, it's a COMMUNITY! Join in and participate with other DSMers, and invite all of your DSM friends to make this place their home. Chat with others, create a build thread, post questions and answers. Get involved! Logging in will also remove many of the advertisements, along with this notice. ;)

ECUflash Injector latency values

Posted by Sjd6795, May 23, 2020

Please Support Fuel Injector Clinic
Please Support VR-Speed Factory
  1. Sjd6795

    Sjd6795 Proven Member

    422
    101
    Joined May 14, 2014
    Wilsonville, Oregon
    Injector latency varies per injector and is suppose to adjust idle AFR. Does increasing latency give more or less fuel though?
     

    Street Build 488  11

    1997 Mitsubishi Eclipse GSX
    awd · manual · 2G DSM
    Sjd6795

    Street Build 1K  0

    1991 Eagle Talon TSi AWD
    manual · 1G DSM
    Loading...
  2. EVLGSX

    EVLGSX Proven Member

    528
    236
    Joined Dec 7, 2017
    Wallingford, Connecticut
    Latency = deadtime= injector on time

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

    edit-had it backwards- fixed
     
    Last edited: May 23, 2020

    Street Build 2K  15

    1997 Mitsubishi Eclipse GSX
    awd · manual · 2G DSM
    Loading...
  3. Sjd6795

    Sjd6795 Proven Member

    422
    101
    Joined May 14, 2014
    Wilsonville, Oregon
    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.
     

    Street Build 488  11

    1997 Mitsubishi Eclipse GSX
    awd · manual · 2G DSM
    Sjd6795

    Street Build 1K  0

    1991 Eagle Talon TSi AWD
    manual · 1G DSM
    Loading...
  4. delta448

    delta448 DSM Wiseman

    2,956
    209
    Joined Jan 13, 2006
    Clarksburg, West Virginia
    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.
     

    2K  5

    1998 Eagle Talon TSi AWD
    awd · manual · 2G DSM

    2K  11

    1997 Eagle Talon TSi AWD
    awd · manual · 2G DSM
    Loading...
    ThunderChild likes this.
  5. motomattx

    motomattx Proven Member

    2,324
    967
    Joined Dec 9, 2010
    wampum, Pennsylvania
    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.
     

    Drag Race Build 4K  24

    1995 Mitsubishi Eclipse GST
    fwd · manual · 2G DSM
    Loading...
  6. Sjd6795

    Sjd6795 Proven Member

    422
    101
    Joined May 14, 2014
    Wilsonville, Oregon
    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.
     

    Street Build 488  11

    1997 Mitsubishi Eclipse GSX
    awd · manual · 2G DSM
    Sjd6795

    Street Build 1K  0

    1991 Eagle Talon TSi AWD
    manual · 1G DSM
    Loading...
  7. delta448

    delta448 DSM Wiseman

    2,956
    209
    Joined Jan 13, 2006
    Clarksburg, West Virginia
    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%.
     

    2K  5

    1998 Eagle Talon TSi AWD
    awd · manual · 2G DSM

    2K  11

    1997 Eagle Talon TSi AWD
    awd · manual · 2G DSM
    Loading...
    Sjd6795 and steve like this.
  8. steve

    steve DSM Wiseman

    12,858
    633
    Joined Feb 3, 2002
    Boulder, Colorado
    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.
     

    2

    2008 Audi TT 3.2 Quattro Roadster
    awd · manual · Misc Vehicles

    4

    2002 Audi TT Quattro Roadster 225
    awd · manual · Misc Vehicles

    23  2

    1992 Dodge Stealth RT/TT
    awd · manual · 3000GT/Stealth

    4K  12

    1991 Mitsubishi Eclipse GSX
    manual · 1G DSM
    Loading...
    Sjd6795 likes this.
  9. Sjd6795

    Sjd6795 Proven Member

    422
    101
    Joined May 14, 2014
    Wilsonville, Oregon
    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.
     

    Street Build 488  11

    1997 Mitsubishi Eclipse GSX
    awd · manual · 2G DSM
    Sjd6795

    Street Build 1K  0

    1991 Eagle Talon TSi AWD
    manual · 1G DSM
    Loading...
  10. steve

    steve DSM Wiseman

    12,858
    633
    Joined Feb 3, 2002
    Boulder, Colorado
    So how do your AFR's match up to your fuel maps?
     

    2

    2008 Audi TT 3.2 Quattro Roadster
    awd · manual · Misc Vehicles

    4

    2002 Audi TT Quattro Roadster 225
    awd · manual · Misc Vehicles

    23  2

    1992 Dodge Stealth RT/TT
    awd · manual · 3000GT/Stealth

    4K  12

    1991 Mitsubishi Eclipse GSX
    manual · 1G DSM
    Loading...
  11. Sjd6795

    Sjd6795 Proven Member

    422
    101
    Joined May 14, 2014
    Wilsonville, Oregon
    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
     

    Street Build 488  11

    1997 Mitsubishi Eclipse GSX
    awd · manual · 2G DSM
    Sjd6795

    Street Build 1K  0

    1991 Eagle Talon TSi AWD
    manual · 1G DSM
    Loading...
  12. stillrunning

    stillrunning Proven Member

    112
    53
    Joined Oct 10, 2013
    brandon, Florida
    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.
     

    Street Build 501  3

    1997 Mitsubishi Eclipse Spyder GST
    fwd · manual · 2G DSM
    Loading...
    Sjd6795 likes this.
  13. Sjd6795

    Sjd6795 Proven Member

    422
    101
    Joined May 14, 2014
    Wilsonville, Oregon
    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.
     

    Street Build 488  11

    1997 Mitsubishi Eclipse GSX
    awd · manual · 2G DSM
    Sjd6795

    Street Build 1K  0

    1991 Eagle Talon TSi AWD
    manual · 1G DSM
    Loading...
  14. Sjd6795

    Sjd6795 Proven Member

    422
    101
    Joined May 14, 2014
    Wilsonville, Oregon
    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.
     

    Attached Files:

    Street Build 488  11

    1997 Mitsubishi Eclipse GSX
    awd · manual · 2G DSM
    Sjd6795

    Street Build 1K  0

    1991 Eagle Talon TSi AWD
    manual · 1G DSM
    Loading...

Share This Page

Support Vendors who Support the DSM Community
ECM Tuning ExtremePSI Feal Suspension Fuel Injector Clinic Jacks Transmissions JNZ Tuning Kiggly Racing Morrison Fabrications OHM Racing RixRacing RockAuto SouthBay Fuel Injectors STM Tuned Track Decals Track Sculptures VR Speed Factory