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Thread: Installed new exhaust gas sensor-Missing

  1. #1
    Registered User 81 ZXT's Avatar
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    Default Installed new exhaust gas sensor-Missing

    81 Turbo - I bought 2 years ago. Fixed a lot of problems but have always thought it was running rich. Changed the exhaust gas (O2) sensor. Now it seems to run leaner (better gas milage and less unburnt gas smell) but it misses at idle. The idle speed has not changed (800 rpm) but there is a miss. Seems to run OK down the road-checked the plugs yesterday and they looked good. Is there anything I should look for? I have already checked:

    Plug wires - good
    Plugs - good
    Dist cap/rotor - good
    Timing - Spot on
    Coil - replaced just before o2 sensor

    Any ideas??

  2. #2
    Registered User 81 ZXT's Avatar
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    OK, so I unplugged the exhaust gas sensor and even though it runs rich, the missing is gone. So with the sensor working, I'm running lean. Could there be another sensor that is bad causing a conflict with the exhaust gas sensor?

  3. #3
    Registered User 81 ZXT's Avatar
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    OK, so I posted my first plea for help about 2 1/2 weeks ago. Now I realize that I am not an expert, but I see a lot of "non-experts" posting here and getting responses. With the exhaust gas sensor plugged in, I'm getting 17.73 mpg. With it unplugged, I get 15.88 but I have a miss at idle and it is very sluggish when cold. When I first start it up it idles OK but will not take any throttle without backfiring thru the intake and kind of stalling like it is starving for fuel. I am thinking that maybe my head temp sensor could be bad. If it does not realize that the head is heating up, it is simply controlling the injection pulse from readings supplied by the cooling temp sensor and the O2 sensor? I know there are a lot of other factors involved but does anyone have any ideas on what to look for?

  4. #4
    Mike B
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    There don't seem to be a lot of ZX owners on this site, so maybe that could have something to do with your lack of responses. Sorry, I wish I could be of some help, but my only experience is with 240Z carbed engines.

    -Mike

  5. #5
    Rust Free'ish zKars's Avatar
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    The best thing to do is get the fatory service manual (xenons130.com) and do ALL of the EFI system checks to track down the culprit methodically. Clean every electrical connection you can find as well to all the sensors and input, start with the head temp sensor.
    -----------------------------------------
    Jim
    73 240Z HLS30 149331
    69 510 PL510 77603

    www.zKars.com
    www.calgaryzclub.ca
    Reference materials
    www.xenonS30.com

  6. #6
    Registered User 81 ZXT's Avatar
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    I think you are right. I will start at the beginning (always a good place to start) and go thru all of the checks in the service manual. Something has to be out of whack.

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