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throwing CEL after swap.

Discussion in 'HYBRID -> EG-EK / DC' started by seephor, Feb 8, 2005.

  1. seephor

    seephor Member

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    I swapped a jdm b18c into my 97 gsr. Converted everything to USDM spec so running a us ecu. I'm getting a weird CEL when I first start the car in the morning. After it starts and runs for about 30 seconds. I reset the ECU and start it back up and I get no more cel. I jumped the wire under the passengers side and the code read 91. I couldn't even find that in my helms but found it posted on a forum and it read "fuel tank pressure circuit". What in the hell is this. I can't even find any documentation on it anywhere. But like I said, I get it after starting the car in the morning after it's been sitting over night. Once it starts, I reset ecu and it's gone for the rest of the day. Tomorrow I'm going to open the fuel cap and release the pressure before starting to see if it has something to do with that. Any thoughts?
     
  2. deth101

    deth101 Senior Member

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    maybe the pressure is leaking out overnight and with it moving while driving during the day it could be generating enough pressure to keep up,I'd try a new fuel cap first.
     
  3. seephor

    seephor Member

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    Actually there is pressure built up overnight and even after releasing the pressure I tried starting it and still got the CEL. Though I think I know what the problem is. There's a port where the line from the EVAP solenoid hooks up to on the intake manifold which is smaller in diameter compared to the USDM intake mani. Now The way the ECU knows if the EVAP solenoid is functioning properly is though the MAP sensor. When the car is cold and you start it. The solenoid valve opens which lets more air into the intake mani and that increase in air while the valve is open will show up on the MAP sensor. My theory is that since the port on the intake mani is small that not enough air flows in for the MAP to pick up the change in vaccum pressure so I get a CEL. I rigged up the evap to the brake booster port which should provide plenty of flow so tomorrow morning I'll give it a try and see if I get a CEL.
     
  4. projekteg

    projekteg Senior Member

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    this is why obd2 sucks ;)
     
  5. DelSlo

    DelSlo Senior Member

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    haha , blast you obd 2!!


    i like your theory, and it does make some sense. good luck keep us updated.
     
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