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Thread: Engine rev when in park

  1. #1
    Member
    Join Date:  May 2013

    Location:  Detroit, Michigan

    Posts:    34

    My VIN:    2723

    Engine rev when in park

    When I fire up the car and it is in park the engine starts revving. From about 5 to 15. The lower it drops the higher it revs.
    Sounds like someone is pushing the gas pedal then letting off constantly...the fuel pump would also run for about a minute and if you tried to start the car before it shut off, it wouldn't start.
    A friend said to change the rpm relay...which I did...and the problem stopped for about 2 weeks...now its doing it again.
    Fuel pump cuts off after a couple seconds and the car starts, but just revs
    Any one else had this issue?
    mike

  2. #2
    Delorean Guru
    Join Date:  May 2011

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    I don't think you are describing the problem well. With your foot off the throttle pedal and the pedal all the way to idle, and the car in Park, you say it revs up and down by itself? Then you are saying you have a problem with the fuel pump and a 3rd problem with starting it. To begin, you have an automatic and does it still have the K-Jet fuel system? Has it ever run right? What have you done to it besides the RPM relay?
    David Teitelbaum

  3. #3
    Member
    Join Date:  May 2013

    Location:  Detroit, Michigan

    Posts:    34

    My VIN:    2723

    Okay I will describe it better...
    When I start the car, after it is sitting idle in park for about a minute, the rpms start fluctuating between 5 and 15 if it drops below 5 it jumps to like 20. It does this constantly...like someone is just revving the motor...I can try and take a video tomorrow.
    But as stated I was told the rpm idle relay needed replacing, which solved the problem for a week or so. But now its back. It is the original motor but has been rebuilt.

  4. #4
    Ryan > Ruben Ryan King's Avatar
    Join Date:  May 2011

    Location:  Fresno, CA

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    My VIN:    3997

    That's called "Hunting"

    A very common DeLorean...erm....characteristic? Its very normal.

    Let the car warm up and see if it stops. The car needs to warm up and idle hunting should cease for the most part.

    EDIT-: Also, the exhaust system has an "Open" & "Closed" loop system, which adds to the hunting idle you are experiencing. Maybe another member can explain it better, but essentially the system has to warm up, thus, open loop. Once its warmed up, it falls into a closed loop. Its weird and hard for me to describe. You can take a video of what youre experiencing, but I'm pretty sure its what I stated above.
    Last edited by Ryan King; 10-06-2017 at 09:19 PM.
    Living The Dream Since 2005 - VIN#3997

  5. #5
    Ryan > Ruben Ryan King's Avatar
    Join Date:  May 2011

    Location:  Fresno, CA

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    Is it something like this?

    https://www.youtube.com/watch?v=4FEjgP0si2U
    Living The Dream Since 2005 - VIN#3997

  6. #6
    Delorean Guru
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    Reving when cold without touching the throttle is normal, racing from 500 to 1500 is a lot but not terrible. It should level out to a much smaller amount quickly. How is it once the motor warms up?
    David Teitelbaum

  7. #7
    Member
    Join Date:  May 2013

    Location:  Detroit, Michigan

    Posts:    34

    My VIN:    2723

    https://www.youtube.com/watch?v=WR8VEriaxpQ

    This is NOT a video of my car... but it is exactly what mine does...

    I will fire it up today and let it run longer till warmed up and see what happens.

    Thanks guys

  8. #8
    Senior Member NckT's Avatar
    Join Date:  Jun 2011

    Location:  Yorkshire UK

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    My VIN:    No. 4068

    The surge is a symptom of incorrect base fuel mixture/ incorrect control pressure or idle control.

    See post 19 in:

    http://dmctalk.org/showthread.php?15...umpiness/page2

    Before:

    https://youtu.be/oXy4y5Cpa0s

    After:

    https://youtu.be/Glh_TaTSP1A
    RIP Rob van de Veer Top bloke

    I say Sir, I must be mad, one loves fixing K-Jet !

    Make sure there's plenty in the tank for the weekend chaps....

  9. #9
    Mr. Pickles-mobile Shep's Avatar
    Join Date:  Sep 2011

    Location:  Akron, Ohio

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    Cost of mechanical fuel injection i.e. K-Jet. Mine behaved exactly as you described for years. No real danger, but stalling when approaching red lights got me to go EFI, i.e. electronic fuel injection.

    Think of trying to mechanically mimic a Segway (or "hoverboard" these days), rather than with electronics. It can work, but it's VERY clunky. That's why the automotive industry as a whole abandoned it rather quickly. Trade balancing a weight with balancing an RPM and you get the idea.

    The stalling happened when decelerating on an automatic, so drivetrain load slowing down engine, plus a decreasing RPM as the fluctuation was going from high to low. It was enough to push the engine past its cutoff point and for it to stall.

    End of the day is, for a DeLorean, this is normal. All because DMC picked K-Jet.
    Last edited by Shep; 10-07-2017 at 11:26 AM.
    Proud owner and operator of



    https://Raccin.Industries/

  10. #10
    Senior Member NckT's Avatar
    Join Date:  Jun 2011

    Location:  Yorkshire UK

    Posts:    120

    My VIN:    No. 4068

    Mines an auto and it doesn't stall ...
    RIP Rob van de Veer Top bloke

    I say Sir, I must be mad, one loves fixing K-Jet !

    Make sure there's plenty in the tank for the weekend chaps....

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