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Thread: Cold start; hot no start?

  1. #1
    Poncho
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    Default Cold start; hot no start?

    I want to get some opinions on what's going on with my ' 87 grand marquis. So here's the spill; the car starts fine cold and holds idle. Once it gets up to temperature and the thermostat opens up. If the car is turned off and started back up immediately after, it will turn over but not hold idle without giving it some gas. I'm under the suspicion it has something to do either with the evap canister system or the ignition module. What do you think? Thanks all for the suggestion!
    @Ryan.Madison68

  2. #2

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    Have you tested your coolant temp sensor? It could be as simple as that.


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  3. #3
    I'm an air-conditioned gypsy gadget73's Avatar
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    Coolant temp sensor, or possibly the IAC getting stuck would be my guess too. If it was ignition, giving it some throttle wouldn't help.

    86 Lincoln Town Car (Galactica).
    5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

    91 Lincoln Mark VII LSC SE, triple black (Timewarp) - poly front bushings, KYB struts and shocks, Holley SystemMax1 lower intake, SilverFox AOD valve body,

    1984 Lincoln Continental TurboDiesel - rolls coal

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  4. #4
    Poncho
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    Thanks guys. I'll look into replacing the coolant temp sensor. It seems like most likely place. Is it in front of the motor near the rotor cap?
    @Ryan.Madison68

  5. #5
    The Brown Blob 87gtVIC's Avatar
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    It will be on the passengers side of the motor. near the front on a pipe coming up and out of the lower intake. Two wire plug connected to it.

    When ordering dont mistake it for the one that is on the drivers side directly into the lower intake manifold. That is the one that goes directly to the replace engine light on your dash.
    ~David~

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  6. #6
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    I found this unplugged. Where does it connect to? Thanks 87GTVic

    @Ryan.Madison68

  7. #7
    The Brown Blob 87gtVIC's Avatar
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    Looks like the plug for the replace engine coolant sensor just to the 2 o'clock on your circled portion.
    ~David~

    My 1987 Crown Victoria Coupe: The Brown Blob
    My 2004 Mercedes Benz E320:The Benz

    Quote Originally Posted by DerekTheGreat View Post
    But, that's just coming from me, this site's biggest pessimist. Best of luck

  8. #8
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    Okay. Does it connect on the metal stud right next to it on the valve cover? I tried to plug it back and it didn't fit.
    @Ryan.Madison68

  9. #9
    The Brown Blob 87gtVIC's Avatar
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    If you still have the factory coolant temp sensor for the replace engine light it would fit right over the stud out of the unit.

    If your factory coolant temp sensor for the replace engine light was removed and an after market coolant temperature gauge was put into its place you wont have a place for the wire.



    I circled the sensor in yellow.
    Attached Thumbnails Attached Thumbnails coolant sensor.jpg  
    ~David~

    My 1987 Crown Victoria Coupe: The Brown Blob
    My 2004 Mercedes Benz E320:The Benz

    Quote Originally Posted by DerekTheGreat View Post
    But, that's just coming from me, this site's biggest pessimist. Best of luck

  10. #10
    Poncho
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    Default

    That makes sense. Thanks!
    @Ryan.Madison68

  11. #11
    Poncho
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    I swapped the coolant temp sensor, and it still is having trouble holding idle after a hot start. Any other suggestions? The IAC was recently replaced as well.
    @Ryan.Madison68

  12. #12
    Wagon Addicted Tiggie's Avatar
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    Sounds like you’ve covered the typical problem areas.

    Won’t hurt to set the base idle just in case someone before has screwed with it: https://www.muscularmustangs.com/idlereset.php

    Won’t hurt to check codes. If you don’t have a reader: http://www.fuelinjectedford.com/page13.html note that you don’t have a check engine light so you will need to use the test light or voltmeter.

    Vacuum leaks also do some weird things to these cars. Check those out.
    1988 Crown Vic Wagon - daily
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  13. #13
    I'm an air-conditioned gypsy gadget73's Avatar
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    There is also an air temperature sensor. #5 intake runner, driver's side, looks just about like the coolant sensor.

    Is the IAC a Motorcraft part? Some of the aftermarket ones don't seem to work right.

    86 Lincoln Town Car (Galactica).
    5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

    91 Lincoln Mark VII LSC SE, triple black (Timewarp) - poly front bushings, KYB struts and shocks, Holley SystemMax1 lower intake, SilverFox AOD valve body,

    1984 Lincoln Continental TurboDiesel - rolls coal

    Quote Originally Posted by phayzer5 View Post
    I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

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