ICV voltage 190E 2.3 8V

Discussion in 'Engine' started by Cronzi, Apr 20, 2014.

  1. Cronzi

    Cronzi New Member

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    Mercedes Benz 190E 2.3L 8V
    i have a problem with the IACV in my 190e, the voltage is stuck at 7v (one wire is 14v and the other one is 7v) and of course i have a huge idle, i tried to fix the problem with replacing potentiometer and it did not work, only way to get the idle down is to adjust potentiometer real low and then the duty cycle at idle shows a fault in the system (stuck at 40%) and if i raise it up it goes to 50% and fluctuates (normal) but opens up the idle air control valve and there is no way of adjusting the potentiometer to get the idle valve voltage down, it's either 40% low idle or 50% and high idle,

    i really need your help chaps, thanks
     
  2. SL300-24

    SL300-24 Hardcore MB Enthusiast

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    Are you getting 70% duty cycle with your meter black in pin 2 and red in pin 3 of the diagnostic port with the key on and engine off before you start?
     
  3. grober

    grober MB Club Veteran

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    Try the electrical trouble shooting part of the 190 manual here after downloading it .
    Modified Technologies, Inc | Enthusiast Gear
    Basically what you are measuring is the voltage drop across the IACV. The valve is controlled by being supplied with 12V [ nominal ] on one side from the OVP relay and earthed by a switching transistor in the engine ECU controlling the operating current on the other . The fact its not altering is a bit worrying.
     
  4. OP
    OP
    Cronzi

    Cronzi New Member

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    i have a duty cycle function on my multimeter and i reverse the polarity for my benz, i put black one in 3 and red on in 2

    that way i get 10% duty cycle with micro switch depressed and i usually just disconnect it when i am testing the car, and it goes to 40% unless i adjust potentiometer then i get 50% and HIIIIgh idle :(
     
  5. OP
    OP
    Cronzi

    Cronzi New Member

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    but i havent tested what you said, i will check that out and report back to you
     
  6. OP
    OP
    Cronzi

    Cronzi New Member

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    okay i finished the test and it goes like so

    black in hole 2 and red in hole 3
    ign on 89.9% and micro switch disconnected 29.9%

    red in hole 2 and black in hole 3
    ign on 10% and micro switch disconnected 70%

    hope this helps you help me !
     
  7. SL300-24

    SL300-24 Hardcore MB Enthusiast

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    Don't disconnect anything I am assuming that you have the round diagnostic port and your car has an o2 lambda sensor. With the ignition on but engine off, black in 2 and red in 3 you should get a 70% duty cycle reading.
    If you do not then you have an open loop instead of closed loop but you need to establish this first.
     
  8. OP
    OP
    Cronzi

    Cronzi New Member

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    i have that round diagnostic box and o2 sensor, all connected, so closed loop it is
    okay, then with nothing disconnected and black in 2 and red in 3 i have 89.9 with ignition on, so stuck at 90%

    how should i continue ?
     
  9. SL300-24

    SL300-24 Hardcore MB Enthusiast

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    Have you checked the idle switch and full load switch on the throttle body, not the idle over run switch on the linkage?
     
  10. OP
    OP
    Cronzi

    Cronzi New Member

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    idle switch ? meaning the microswitch that turns is operated by the linkage ? the one with the wheel ?

    i have tested the full load switch , full throttle with engine off and ign on did change the duty cycle
     
  11. SL300-24

    SL300-24 Hardcore MB Enthusiast

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    No the switch in the throttle body?
     
  12. SL300-24

    SL300-24 Hardcore MB Enthusiast

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  13. OP
    OP
    Cronzi

    Cronzi New Member

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    yeah this one !

    how do i test it ? can you give me the specs and how to ?
     
  14. SL300-24

    SL300-24 Hardcore MB Enthusiast

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    Trace the lead the connector is secured by 2 nuts. Pull off the female connector and you will find 3 pins. The centre pin is ground, connect your black meter lead to it. With engine off ignition on...set your meter to ohms, hopefully you have a buzz setting.

    As you look down at the pins from the front of the car the right hand one is the idle. If you place your red lead on this it should buzz.When you open the throttle linkage it should stop buzzing.

    The left hand pin is full throttle. Keep black lead on the centre pin and red on the left pin it should not buzz. Open the throttle wide and it should buzz on full throttle if all is working correctly.

    This is effectively 2 switches in one, idle and full throttle. The signals go back via the KE plug to the ECU.
     
    Last edited: Apr 20, 2014
  15. OP
    OP
    Cronzi

    Cronzi New Member

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    WOW ! you have most certainly saved the day !

    i had another engine in the next village that i scrapped, 1.8 engine, i wanted more power and that is why i put this engine in 2.3

    i went up there and took the TPS unit out of the car and put the multimeter in the test socket, black in 2 and red in 3 and and ign on, i disconnected the TPS unit that was on the engine and no change ! that's when i was smiling !:rock:

    and i connected the donor unit and held it closed and voila ! change !

    so i adjusted the potentiometer to 0.70v and adjusted Co screw to mixture 45-50 and it purred like a kitten !! smoothest idle i ever saw in that car !

    thank you so much buddy, you have saved my ass !
     
  16. SL300-24

    SL300-24 Hardcore MB Enthusiast

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    Glad to be of help........
     
  17. OP
    OP
    Cronzi

    Cronzi New Member

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    You were a big help, i still feel like its lacking power, might be because i am not sure of how to adjust potentiometer perfectly
     
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