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GVR-4 A/F reading 19.4 at ECU o2 signal wire

Posted by Callum Mccawe, Sep 11, 2018

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  1. Callum Mccawe

    Callum Mccawe Proven Member

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    Joined Jun 29, 2017
    Whakatane, New Zealand
    Need some help, I’m seeing an A/F ratio of 19.4-20.0 at the Ecu o2 signal wire, if the car is off but ignition on it says that same reading, if the car is running it’s the same again, if I unplug the o2 sensor connector it is still the same!!! The car is undrivable atm due to a stuck brake Caliper but if I hit the gas quickly while stationary it will dial down to 14.7.....is there a problem with some other sensor cos it doesn’t matter if the o2 is plugged in I still get these lean readings....the car is also running rough, by sound out the exhaust (missing) and by looking at the engine it shudders every now n then like it’s missing......and only happens when car has warmed up, everything seems fine when it’s cold, could this be a bad knock sensor or crank sensor? Clogged injectors? I’m really stuck don’t know where to look next.....Ive got a Datalogger cable and EvoScan software coming in the next few days which I have no idea how to read haha but what should I be looking for in terms of the logging
     

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  2. steve

    steve DSM Wiseman

    12,559
    421
    Joined Feb 3, 2002
    St. Charles, Illinois
    What wideband do you have and where is it installed?
     
    My DSM:
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  3. Callum Mccawe

    Callum Mccawe Proven Member

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    0
    Joined Jun 29, 2017
    Whakatane, New Zealand
    Hi mate, thank you for your reply, I don’t have a wideband o2 I just have the stock narrowband o2 up on the o2 housing, I know I can get accurate readings from it but I’ve had the same gauge before and it would read 14.7 at idle and nothing when car was off, this one is reading 19.4-20 when the car is off and when it is idling, if I hit the pedal a bit it will go down to 14.7....once the car is warmed up it starts popping and stuttering out of the exhaust and the engine shakes a bit and the bonnet shakes around when it is up....the car is also reaching 180 very quickly and the fans are coming on within 5 mins of idling, is this due to lean conditions? Just wondering why the o2 signal wire at the ecu is sensing 19.4 when the o2 is unplugged as well.....is this normal? I have a jap spec 91 mitsi Galant Vr4 RS evo 0 edition...(bigger injectors, bigger turbo, bigger cooler, extra vent in bumper and bonnet etc).
     
  4. Callum Mccawe

    Callum Mccawe Proven Member

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    Joined Jun 29, 2017
    Whakatane, New Zealand
    Also, do you know how to read logs? I have a cable from EvoScan coming and EvoScan software so I could do a log (which I have no idea how to do) and send it to you if you don’t mind....?.... if that’s alright how should I do the log? Wait till car warms up then start log? Or do it from cold start to warming up? Also should I just let it idle or should I rev it a few times during the log?
     
  5. steve

    steve DSM Wiseman

    12,559
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    Joined Feb 3, 2002
    St. Charles, Illinois
    All the narrowband sensor is going to tell you is if it's richer than stoic or leaner. The slope of the voltage change on either side is very steep given that the total swing is 1 volt. The blinking light gauges therefore are only good to see if the ECU is going closed loop and how quickly it's dithering the fuel to make the sensor switch, aside from the excitement of watching the lights blink.

    I've never tried to use EVOScan with a ODB1 ECU. I usually make up a simple passive datalogging cable and use MMCd or an old copy of the TMOlogger.

    Usually, I see anywhere from 0 to 0.4v from the factory narrowband sensor before it's heated up and starts operating. Once it's hot and the ECU enters closed loop the voltage will swing in the 0.4v to 0.8v range as the ECU varies the fuel around 14.7 AFR to force the sensor to switch.

    I usually log everything (all the ODB1 sensors) from turning the ignition on until the car heats up to 190F to see what they sensors report and make sure nothing is acting up is often is the case when the ECU has capacitor leakage damage (all early Mitsubishi ECUs are known to suffer from it).
     
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  6. Callum Mccawe

    Callum Mccawe Proven Member

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    Joined Jun 29, 2017
    Whakatane, New Zealand
    Yes so it is showing that it is leaner and is staying there when warmed up as well, the o2 voltage reads 0.0-0.1, the o2 sensor is not heated and is a 2 wire factory evo 0 or 2nd facelift Vr4 sensor, I’m just wondering why it’s always seeing a lean state and the car also sounds like it’s running rough through looking at the engine and hearing the exhaust, the idle however is solid and consistent even when the engine seems to be missing and shaking a bit.....ok so can I download MMcD and log all the sensors or see them all in real time? If so can you give me some advice on getting it/ downloading it and how to view all the sensors etc on mmcd please?
     
  7. Callum Mccawe

    Callum Mccawe Proven Member

    27
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    Joined Jun 29, 2017
    Whakatane, New Zealand
    Also the blinking gauge is the Apexi turbo timer LOL and yea it is just sensing 19.4-20 the whole time, maybe I should wait for the logger and see whether or not the o2 voltage corresponds to that reading....also is it normal for the sensor wire to see 19.4 (through the apexi) with the o2 sensor disconnected and connected.....I mean I know the source of my readings is t accurate when the car is running etc but would that also mean the gauge is lying in terms of seeing that really lean reading at idle? In other words that signal wire on the ecu isn’t actually seeing 19.4/ around 0.1 from the o2 sensor and it’s not sitting in a lean condition?
     
  8. Vegas smith

    Vegas smith Proven Member

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    Joined Dec 2, 2002
    Houston, Texas
    This is not normal. I'm confused, but you are using a narrowband gauge to get these readings? There must be some type of connection issue or the gauge is broken...or I just don't understand what's going on here.
     
    My DSM:
    1993 Eagle Talon TSi AWD

    Street Build

    GT30   manual
    1992 Eagle Talon TSi AWD (sold)

    16g   manual
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  9. Callum Mccawe

    Callum Mccawe Proven Member

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    Joined Jun 29, 2017
    Whakatane, New Zealand
    Yea bro....well not really, it’s not a gauge as such, it’s the built in AF and o2 gauge thing on the apexi turbo timer....I’m hoping it’s just that since it still reads the same with the o2 sensor unplugged.....just got my Datalogger cable today so I will plug it in tomorrow and see what’s happening, do you know what the best program is to watch the sensors/rpm/temp etc in real-time? And would you please be able to given me a quick rundown how to do it or if I need to set anything up in order to watch the sensors?
     
  10. Callum Mccawe

    Callum Mccawe Proven Member

    27
    0
    Joined Jun 29, 2017
    Whakatane, New Zealand
    Thanks Steve and Vegas Smith for your inputs and advice so far as well, it nice to bounce ideas and opinions off people with knowledge, im from New Zealand and although there is a big Mitsi and Vr4 community it’s hard to get replies and help, maybe because there’s f*** all people that live here haha but anyway Thank you and I hope I can get this sorted with some peoples help
     
  11. Vegas smith

    Vegas smith Proven Member

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    Joined Dec 2, 2002
    Houston, Texas
    Well, the best option is to spend the money and buy ecmlink. I think it's $550 new and sometimes you can get it used for 4-450. This will give you all the tuning and monitoring you'll ever need and is what 90% of the community uses.
     
    My DSM:
    1993 Eagle Talon TSi AWD

    Street Build

    GT30   manual
    1992 Eagle Talon TSi AWD (sold)

    16g   manual
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  12. Callum Mccawe

    Callum Mccawe Proven Member

    27
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    Joined Jun 29, 2017
    Whakatane, New Zealand
    Yea I’ve heard it doesn’t function properly on jap spec ecu’s...if I was gonna fork out 550 usd which is about 800nzd I may as well for out another 400 and get a full plug in LinkG4+....so yea I’m not going to be spending that kind of money so I’ve just got to work with what I have
     
  13. Vegas smith

    Vegas smith Proven Member

    2,048
    895
    Joined Dec 2, 2002
    Houston, Texas
    The problem is you don't really...have...anything to tune with? In my experience, you can get by like that at low power levels. Once you upgrade the turbo and cams you really need a way to fine tune the car because the airflow characteristics of engine change so much.
     
    My DSM:
    1993 Eagle Talon TSi AWD

    Street Build

    GT30   manual
    1992 Eagle Talon TSi AWD (sold)

    16g   manual
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  14. Callum Mccawe

    Callum Mccawe Proven Member

    27
    0
    Joined Jun 29, 2017
    Whakatane, New Zealand
    Ok I just put the logger on and my Ecu is seeing 195 degrees F and my gauge only says 170 degrees F, engine coolant temp sensor is brand new, also my throttle position % says 15.68 should that be 10? Tuning advance is at -5 deg with car off ignition on, is that right? With car on it ranges from -5 to 4.... I’m going to post up a small video of the Datalogger so can someone weigh in and let me know if there’s anything that’s out of whack or not normal?
     
  15. Callum Mccawe

    Callum Mccawe Proven Member

    27
    0
    Joined Jun 29, 2017
    Whakatane, New Zealand
    here is my log, my timing advance is all over the show when rpm settles but according to the timing light its fine?? log is just of idle
     

    Attached Files:

  16. AntmanAndLittleDi

    AntmanAndLittleDi Proven Member

    129
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    Joined Nov 12, 2014
    Russell, Kansas
    Hey Callum, if you don't mind I'm going to eavesdrop on your thread. My car is doing the Exact same thing only mine is a 1999 Eclipse GST. I think it's amazing we have the same problem and two completely different ecus. I just downloaded EvoScan last night and found a logging cable. Going to plug it in after I get off work later tonight and see what I get. Before I got EvoScan I went through a bunch of checks to see if I could find a physical problem, but nothing helped. I even plugged in bigger injectors to get it off of a 19 afr, but it was no use. Hopefully between the two of us we can get it figured out. Unfortunately it'll be the blind leading the blind, I've never ran any logging data either, this will be my first time. My first post is below this one a bit titled Sudden 19.x:1 AFR. You can see my full list of everything I checked and changed, just to go right back to where I started because nothing helped. I'm also fighting the ecu in its "learning" mode as I had reset it when I switched the injectors. I'm hoping it's ok for me to log while in "learning" because that's where I'm stuck at. My car runs great while in cold enrichment, but as soon as it heats up, it shuts down fuel to the 19s and wants to die. I'm not brave enough to let it run too long like that as I've already rebuilt the engine once and still suffer from DSM related PTSD LOL. I'll get my log done tonight, I'm off work in 2 hours and will get things laid out for supper, then plug in the car and share it here.

    Update: It just took me until 9:30pm to get the laptop to recognize my cable. A solid 4 hours of cussing, deleting software, reinstalling software, downloading drivers, rinse, repeat, and somewhere along the 10th try it worked. No idea what I did differently, wish I knew so I could do it again next time and save 3 hours and 50 minutes of my time to do something productive. As it is, it's all ready, for tomorrow. I have to get up for work at 5am or I'd still try reading it tonight, and truth be told I also don't want to go play with the mosquitoes tonight LOL. I'll definitely do it tomorrow.
     
    Last edited: Sep 16, 2018 at 9:43 PM
    My DSM:
    1999 Mitsubishi Eclipse GST

    Road Race Build

    16g   automatic
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  17. Callum Mccawe

    Callum Mccawe Proven Member

    27
    0
    Joined Jun 29, 2017
    Whakatane, New Zealand
    Yea mate let me know how you go, I’m gonna change my fuel pressure reg and o2 sensor and see if that does anything, I have to wait like 2 weeks for the parts though but il keep u updated on my progress
     

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