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Thread: Circuit opening relay.

  1. #1
    Junior Member Automotive Encyclopaedia
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    Default Circuit opening relay.

    I've had one of the commodore MRA in tank setups (thanks Castle Hill Auto One, it's awesome) installed to replace the old external pump on my ra23.

    I've had an electrical gremlin which caused the engine to just die (fuel pump stopped working I'm told was the diagnosis. I couldn't tell from in the car as the new setup is enjoyably quiet) the auto sparky advised problem was dirty contacts on a relay (I think he was referring to the COR). He cleaned the relay and the pump works fine now, but I've got another issue that I'd like to diagnose rather than throw more money at it.

    After a cold start, the engine often stalls at first idle. This problem has been around for a while even with the old setup. Previously I would just hit the ignition (from the on position) and off I'd go, no dramas. Now, if the engine stalls or even if the idle simply drops low without the engine stopping, the car stalls when I hit the accelerator and wont start from the ignition already on position. I have to turn the ignition fully off and then restart.

    I think this is consistent with the COR being dicky. Before I replace the COR (part No. 85910-30050 which seems mad common in toyotas) is there anything else that might cause this symptom?

  2. #2
    RZN169R+2JZGTEVVTI+R151 Domestic Engineer madmont's Avatar
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    Default Re: Circuit opening relay.

    Do you have an IACV which is possibly not working properly?
    Jealousy is a curse

  3. #3
    Junior Member Automotive Encyclopaedia
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    Default Re: Circuit opening relay.

    I will check. Thanks for the idea.

  4. #4
    Junior Member Backyard Mechanic jondee86's Avatar
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    Post Re: Circuit opening relay.

    The functioning of the COR is covered in this article by Wilbo666... http://wilbo666.pbworks.com/w/page/4...pening%20Relay



    Depending on which type you have and what was done to "repair" you COR, there is one scenario that could explain the strangeness when starting after a stall. If you have an ECU controlled COR it may have been incorrectly wired to send power to the COR without having the ECU in the loop. Then your engine would start from the ON position. If the repair changed it back to the correct circuit, the ECU probably "latches" in the OFF state after a stall, and needs to be reset by powering down and then up again.

    I seem to recall way back in the dim and distant past that this was a thing with old cars after a stall or fail to start. Just conjecture on my part but I do like a good mystery

    Cheers... jondee86
    Last edited by jondee86; 03-12-2019 at 06:01 AM.

  5. #5
    Junior Member Automotive Encyclopaedia
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    Default Re: Circuit opening relay.

    Well then. Looks like I have some learning to do.

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