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  1. #1
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    RPMs in between shifts

    I own a '02 GTS; 5 years now. I've noticed when I engage the clutch to shift gears, the rpms never drop below 1200. It will only drop to idle rpms (850) when the car travels under 10 mph. I have even tried getting up to speed (30, 40, etc.) throw it in neutral and the rpms will not drop below 1200 until it slows down to 5-10 mph.

    When it is stopped, it idles perfectly at 850. I've tried a half dozen possible fixes but none have been successful. It may have been doing it since I've owned the car, but I only noticed it about 6 months ago. Any history on this?

  2. #2
    Old surfer, another member had this very situation.
    I’m sorry dude, I don’t remember the thread title, but I’m pretty sure it was within the last couple of months. Maybe do a little look-see.?

    Maybe someone will chime in.

  3. #3
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    Vacuum leak?
    Hopefully, you have already eliminated a floor mat issue.

  4. #4
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    The very early '96 Gen 2's had some problems with stalling on decel with the throttle slammed shut. Dodge had the dealers reflash the PCMs to add an intermediate step speed before idle. I think the IAC just didn't react quick enough on the 8.0l engine.

  5. #5
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    Idle should not be 850. Here's my graphic on reading the tach if that's applicable to this thread.

    Graphics1.jpg

  6. #6
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    Thanks Dave. I thought that line was 850, so the idle is at 750. I read somewhere that factory spec idle is 660?
    Last edited by Old Surfer; 05-09-2022 at 04:05 PM.

  7. #7
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    I'm pretty sure the target idle speed on mine is 704 rpm. The IAC steps around by 10-20 rpm chasing the number.

  8. #8
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    Quote Originally Posted by GTS Dean View Post
    Dodge had the dealers reflash the PCMs to add an intermediate step speed before idle.
    This is tunable with HP Tuners on a Gen3, known as idle decay or idle dashpot.

  9. #9
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    IIRC the idle speed has been increased by the factory as of a certain MY. I don't remember the exact year but certainly after 1998. Reason was the rough idle of earlier Gen2 (like mine) which was not much appreciated by many owners...

  10. #10
    I've experienced this on many of my manual transmission fuel-injected cars. Sounds like normal operation to me!

    The engine computer will take into account the vehicle speed and keep RPMs above idle via the IAC in order to keep vacuum higher to help with power braking. One the car slows down, the computer adjusts the IAC to return to normal idle.

  11. #11
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    Quote Originally Posted by DoomGuy View Post
    I've experienced this on many of my manual transmission fuel-injected cars. Sounds like normal operation to me!

    The engine computer will take into account the vehicle speed and keep RPMs above idle via the IAC in order to keep vacuum higher to help with power braking. One the car slows down, the computer adjusts the IAC to return to normal idle.
    Agreed. Every car that I own does this over a certain mph.

  12. #12
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    Interesting. I was just on my SCT tuner this AM messing with my decel fuel tables. I hate the decel and wish I could turn it off completely. SCT lets you "try" and change decel settings but to date, nothing that I've changed in the tune actually results in any change driving. Factory is something like 2.8 second delay to enable decel fueling and the MPH gate is 27...which is what your are experiencing between shifts and coming to a stop or back to idle (clock decay and MPH gates). Right now I bumped the clock delay to enable decel fuel to 30 seconds and bumped the MPH to enable decel fuel to 50...so in theory I should not get any decel fueling triggers below 50 MPH and if I do, it should take 30 seconds of clock decay prior to enabling the fuel decel...yeah in theory. The fields turn RED when I make the changes so I'm thinking the system won't allow those changes...but SCT sucks and doesn't tell you what is allowed or not....reflash, try, and reflash, try, and so forth...hundreds of times over the past 10 yrs. With the big cam I have, driving around in stop and go traffic is irritating when the decel fuel keeps kicking in. Hate hate hate it.

  13. #13
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    Those increased decel RPMs are even more fun when you have a really loud car. People be looking at you like, bro...?

    Mentioning that for a friend.


 

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