CA18DET factory ECU problems

Thread in 'Technical Questions' started by juss, May 10, 2020.

  1. juss

    juss New Member

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    Hello.


    I have weird problem with my CA18DET factory ECU, My engine came from factory with automatic gearbox but now I have manual gearbox and engine Ecu for manual gearbox. But I have tryed 3 different ECUs but all of them have weard problems.
    All ECUs are 2371-39FF00
    Ecu one: when RPMs are troping they are stopping on idle for a second, then dropping to 500 and up to ide again.
    Ecu two: Same as ecu one but do not rise idle RPMs from 850, disconnect aac and reconnect, worked as ecu one.
    Ecu three: worked fine until I tested spark plugs and now when I turn off the ignition switch nothing is happening, until I unplug ECU relay. I think I burned something in ecu.
    I have deleted all things what can mess up idling except aac valve. I have cleaned and replaced aac valve many times.
    If it helps I can make video from 3 different ecu...

    My question: Why is those CA18DET factory ecus so problematic when dropind to idling? Is there some components what are failind becaus they are quite old?
     
  2. pointz

    pointz Member

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    Could be a number of things, I've never had any issue with oem ECU's.

    Boost / vac leak
    Throttle position sensor
    Idle switch
    Maf
     
  3. juss

    juss New Member

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    Thanks for reply!

    Boost/vac leak I have searched many times using brake cleaner, no luck.
    I have tested all components many times as service manual are saying.
    I'm going to try test everything again when engine is running, measuring with multimeter from ECU socket.
    I suspected MAF, I have 90 degree elbow between turbo and MAF. I mounted honeycomb in front of MAF but no change.

    Interesting is when engine is idling everything is smooth, when I rev it so that engine is holding vacuum, dropping to idle is good, but when I rev it harder that turbo is making boost then dropping to ide is bad. Bigger the boost, bigger the problem. Some time engine are stall.
    I have wideband gauge, when engine RPMs are dropping then AFR is dropping to 20 or even more.
    I was suspected ECU because when I changed it then my problem changed.
     
  4. juss

    juss New Member

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    Tested all components from ECU socket, all reading except Idle switch (+ side) was fine.

    Idle switch (-side) was as manual are saying:
    Throttle valve idle position 8 - 10v is 9v
    Any position except idle 0v is 0v

    But (+ side):
    Throttle valve idle position 8 - 10v is 0,5v
    Any position except idle 11- 14v is 2,4v


    Here are video how ECU 1 is behaving:
     
    #4 juss, May 11, 2020
    Last edited: May 12, 2020
  5. juss

    juss New Member

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    I tested everything again!
    Of course I made measuring error last time!!!

    Throttle valve + side:
    Throttle valve idle position 8 - 10v is 9,5v
    Any position except idle 11- 14v is 12,4v

    BUT Air flow meter is reading little bitt off:
    2500RPM is 1.9v
    3400RPM is 2,2V
    Manual is saying that on 2500RPM should be 2,2v...

    I pressurised intake, no leaks.
    I tested A/T engine ECU, no problem when engine is going to idle!!!!

    Can it be that I have miss some wire or component what I have to cut or change?
    Can it be that my wideband sensor are in wrong place or I have air leak in exhaust?
    ECU doesn't like wideband gauge simulated narrowband voltage?
     
  6. juss

    juss New Member

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    Problem solved!!!



    Multimeter are showing MAF voltage, Middle red gauge is A/F ratio, bottom left is intake manifold pressure.

    It's interesting that I remember from other forums that between turbo and MAF there have to be at least one 90 degree bend that they aren't "seeing" each other.

    What pipe size is better between turbo and MAF 60mm (factory pipe) or 80mm (between MAF and air box in my car)?

    I'm planning to move MAF other side of the engine, wher my air box is located.
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