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ECUflash Weird AFR change

Posted by Sjd6795, Jun 4, 2020

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  1. Sjd6795

    Sjd6795 Proven Member

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    So finally got my cruising AFR up to around 13 and out of no where a day later they just went to 11 and it wants to stay there. My Idle and WOT did not change at all so it has me confused. Any ideas on what could change cruising AFR but not change the WOT and idle?
     

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    1997 Mitsubishi Eclipse GSX
    322 whp · 331 lb/ft · 2G DSM
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  2. motomattx

    motomattx Proven Member

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    It sounds like enough engine run time has elapsed that your mid fuel trims have updated fully and thats why your cruising afr was ok and now its off, the ecu could have applied its trims to it and put it out of where you want it, this means that your injector settings maybe aren't what you need etc.
     

    Drag Race Build 4K  10  24

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

    Sjd6795 Proven Member

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    The injector settings have stayed the same for the longest time and no issues. The only thing I did adjust a few days prior to it happening was my MAF smoothing because I was seeing 10.5-11 cruising AFR after that is when it was around 12.5-13 but then changed itself back to 10.5-11.

    The ROM I use has the big maps enabled and the big maps fuel trim table is adjusted nicely. However I noticed the normal fuel trim tables are all out of whack across the load/rpm it is set to 10.8. But these should not be being used with big maps enabled correct?
     

    Street Build 737  13

    1997 Mitsubishi Eclipse GSX
    322 whp · 331 lb/ft · 2G DSM
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  4. motomattx

    motomattx Proven Member

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    I cant answer that question because it has been so long since I have used a black box ecu or any factory ecu for that matter, just going off of what I remember here, the stand alone ecu's dont have fuel trim updating in the same concept that the factory ones do, when you shut the key off on a stand alone things reset to zero and start over.
     

    Drag Race Build 4K  10  24

    1995 Mitsubishi Eclipse GST
    fwd · manual · 2G DSM
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  5. EVLGSX

    EVLGSX Proven Member

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    This is a good question-

    Until you find the answer, I would just set up all maps to match the best you can
     

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

    Sjd6795 Proven Member

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    Very strange I am changing the fuel maps but it seems when I change the High Octane Fuel Map 1 it causes things to change in my High Octane Fuel Big Map as well.
     

    Street Build 737  13

    1997 Mitsubishi Eclipse GSX
    322 whp · 331 lb/ft · 2G DSM
    Sjd6795

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    1991 Eagle Talon TSi AWD
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  7. EVLGSX

    EVLGSX Proven Member

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    that woulds suggest that they are one in the same---

    only difference is the big map has better resolution?
     

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    1997 Mitsubishi Eclipse GSX
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  8. Sjd6795

    Sjd6795 Proven Member

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    Yeah the big map goes to 9000 RPM and 340% Load
     

    Street Build 737  13

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    Sjd6795

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  9. stillrunning

    stillrunning Proven Member

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    The fuel maps are only for open loop operation, like initial startup, heavy throttle and WOT, they don't affect your cruising at all
    If everything is working as it should the ecm will always trim the AFR to 14.7 except for a short while after startup where it runs in open loop
    If you're seeing anything but ~14.7 afr while cruising you need to figure out why you O2 sensor and ecm are not able to make the proper adjustments
    Even the fuel maps are just a ecm target and don't mean the ecm will hit that number, you have to get your MAF dialed in first to get the fuel calculations the ecm performs corrected
    When things are correct with your MAF tuning when you go WOT your AFR will swing perfectly to the target AFR without much if any fluctuations or overshooting

    Also I wouldn't be even messing with big maps and alternative configurations until you have a better grasp of what's going on with the stock tuning, it just muddies the water so to speak
     

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    1997 Mitsubishi Eclipse Spyder GST
    fwd · manual · 2G DSM
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  10. Sjd6795

    Sjd6795 Proven Member

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    It's so strange I just went out and let my car idle for a good 20 minutes. I used EVOscan to make sure my biss screw was adjusted properly and tps was 12.1% at idle.

    My car will idle around 840 RPM with 14.7-15 AFR then a few minutes later it would idle around 1000 with 12.7 AFR. It kept fluctuating every few minutes back and forth.

    My car never had a stock tune on it when I got the car, English racing had dropped a 2.3l stroker in the car and tuned it to 15 psi on a 14b for the previous owner. I installed some things including a 16g turbo, wideband gauge, FP turbo intake pipe, FP exhaust manifold, 190lph rewired fuel pump and fixed any air leaks that I had.

    Idle fluctuate video. You can hear when the idle changes I didn't get a recording of the AFR when it goes to 14.7 on the lower idle but soon as the idle spikes to 1000 it's 12.7 afr then when idle lowers to 850 it reads perfect at 14.7


    I took a picture of this in evoscan which is strange because this doesn't have the full range of the big map and does not match up to any fuel maps that I have when I pull the tune off the car and load it into ecuflash. According to evoscan it is idle around 120% load because thats where 12.7 is on this map.
    20200605_121628.jpg
    Here is what my actual big map looks like from ecuflash
    20200605_123751.jpg
     

    Street Build 737  13

    1997 Mitsubishi Eclipse GSX
    322 whp · 331 lb/ft · 2G DSM
    Sjd6795

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    1991 Eagle Talon TSi AWD
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  11. Sjd6795

    Sjd6795 Proven Member

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    Went out for a long cruise about 30 minutes each way and at some point the afr during cruise would be around 13.5 then drop to 11 then eventually several miles later back to 13.5. I got a new o2 sensor coming wednesday so maybe that will make a change but I have no idea at this point. Once the car has also been running for a while 30+ minutes it starts to die when pushing clutch in to come to a stop. TPS and BISS have been adjusted correctly. The whole car just breaking I guess.
     

    Street Build 737  13

    1997 Mitsubishi Eclipse GSX
    322 whp · 331 lb/ft · 2G DSM
    Sjd6795

    Street Build 1K  0

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

    stillrunning Proven Member

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    Evoscan doesn't know anything about your actual tuning break points which is why your maps don't match up between ecuflash and evoscan, you have to load your tune settings into Evoscan so it displays the same break points and values
    The graphing function is by far better for spotting oddities in your tune than watching the live trace maps, learn to use the graphing and how to scale the data to make sense to you
    You want things like your AFRmap and WBO2 scaled the same so you can see any deviation between them
    Can't tell you why your car is doing what it is but if you're AFR at warm idle and cruise doesn't fluctuate around 14.7 you need to figure out why
    The only time it should apply something other than 14.7 is moderate/high load and WOT at which point it goes open loop and uses the fuel map setting
    Also you really need to have the MAF dialed in, dialing in the MAF is the cornerstone of everything else working smoothly
     

    Street Build 597  3

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

    Sjd6795 Proven Member

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    I'll do some research on the MAF but I figured that wouldnt be out of whack it's a stock 2g maf and all the settings are correct for it. It's almost as if my car goes open loop at idle and cruise sometimes

    I'm almost debating to go speed density. I noticed I have settings for that in ecuflash.
     

    Street Build 737  13

    1997 Mitsubishi Eclipse GSX
    322 whp · 331 lb/ft · 2G DSM
    Sjd6795

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

    stillrunning Proven Member

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    Going SD probably isn't going to fix the issue you are having, MAF's work absolutely fine and are very easy to tune/calibrate
    Both ways give the ecm a form of airflow estimation from which it calculates the proper amount of fuel to apply
    If either SD or MAF are not properly calibrated then the amount of fuel the ecm calculates will always been wrong
    If you changed injectors you need to recalibrate the MAF as you would also do with with SD
    When closed loop is properly functioning the O2 sensor will always try to trim the fueling but when in open loop there isn't any effective correction
    So you need to have the MAF adjusted so that actual AFR on your WBO2 matches AFRMap
    You're not going to just jump in there in do a few clicks to make things work, it takes allot of seat time to figure out what your looking at and how it all works together, make a change log and see the effects
    I will say it's definitely simpler to adjust a MAF curve with a handful of break points vs an entire SD VE map with many more break points
    Either way works but if you're having a hard time with the MAF going SD isn't going to make things any easier
    I think it was eatsleepdsm or a site something along those lines that I got allot of good info from long ago
     

    Street Build 597  3

    1997 Mitsubishi Eclipse Spyder GST
    fwd · manual · 2G DSM
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  15. Sjd6795

    Sjd6795 Proven Member

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    So I think I have my issue resolved not 100% sure until I drive the car to work today. My o2 sensor wouldn't throw a CEL and it seemed to cycle on the voltages occasionally but I guess not nearly enough and it would hang up in open loop for a while. I just got my Denso o2 in today from rockauto and got it installed. On startup my car idled around 14.6-15 and usually the car would idle around 12.5-13.3. I let it idle for several minutes and nothing changed still a perfect idle AFR.

    The other issue I would have is after doing a WOT pull it would stay stuck in open loop for a long period of time, I hope once I go drive the car today 15 minutes to work it will cycle back into closed loop during cruise.
     

    Street Build 737  13

    1997 Mitsubishi Eclipse GSX
    322 whp · 331 lb/ft · 2G DSM
    Sjd6795

    Street Build 1K  0

    1991 Eagle Talon TSi AWD
    manual · 1G DSM
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