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Thread: HEMI idle?

  1. #1
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    HEMI idle?

    Could you guys help me out with my engine idle? Are you fellow RT owners experiencing some driveline feel at idle, or is it smooth. I'm not sure I'm an accurate judge because my last car had a Honda V6 in it. I never, really never felt the driveline in my ACURA CL 3.2 Type S. It was melted butter smooth all the time! Even after 4 years and 70k miles. I was expecting near the same thing with the HEMI, but I'm not getting it. It's wierd because when I fiirst pull up to a light the idle starts out as smooth, but several seconds INTO the light wait time it seems to not fire on all 8 consistently. This causes driveline vibration INTO the cabin. Any input?



  2. #2
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    My Hemi idles a bit rough, but the explanation FROM my dealer is because its the cam shaft. Not sure if anyone else was told this or not.
    I miss my Maggie

  3. #3
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    iding rough too

    My RT idles rough and has since early on in it's 3300 miles. I haven't looked INTO it yet. Wouldn't mind any helpful suggestions. I'm using 87 gas mostly. Going for my first oil change soon.

  4. #4
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    Switch to 89 gas and let it run for a few miles and see if that changes it at all... 89's recomended


  5. #5
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    Quote Originally Posted by Fred
    Switch to 89 gas and let it run for a few miles and see if that changes it at all... 89's recomended
    Nah, that's not it. I've used 89 since day 1. 800 miles later I still have the same rough idle.

  6. #6
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    I only have 1600 miles on my RT and have used strictly 89 octane and the idle is as smooth as a 1996 Lexus LS400 that I used to own. My car was built in October so maybe later cars have different software tuning?

  7. #7
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    Quote Originally Posted by Bobs05RT
    I only have 1600 miles on my RT and have used strictly 89 octane and the idle is as smooth as a 1996 Lexus LS400 that I used to own. My car was built in October so maybe later cars have different software tuning?
    Nah, that can't be it either. My car was built mid October and has 900 miles on it. However, I'm glad to hear FROM someone that is happy with their idle!

  8. #8
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    i wish i didn't see this post because so far i haven't noticed a thing, but i fear that now i'll look for it and i'll notice it forever... that's okay though, just means i gotta turn my music louder to take my mind off it, hehe

  9. #9
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    Somewhere in one of these threads, it's the MDS, no reason to thump all 8 cyl. at a stoplight.
    My other car has 3 pedals and 100 more inches.

  10. #10
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    hemiunderglass,

    I SUSPECT it's the camshaft profile. If anyone can find the advertised duration at .050, it would be easy to determine for sure. Anything over 220 degrees of duration @.050 will not have a butter smooth idle.

    To develop one HP per cubic inch, you will HAVE to have a fairly aggressive camshaft profile, no way around it. Personally, HAVING the "slight" idle bump lets me know I gotta' 340 HP Hemi "thumpin" under the hood

  11. #11
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    Quote Originally Posted by schmeky
    hemiunderglass,

    I SUSPECT it's the camshaft profile. If anyone can find the advertised duration at .050, it would be easy to determine for sure. Anything over 220 degrees of duration @.050 will not have a butter smooth idle.

    To develop one HP per cubic inch, you will HAVE to have a fairly aggressive camshaft profile, no way around it. Personally, HAVING the "slight" idle bump lets me know I gotta' 340 HP Hemi "thumpin" under the hood
    I could buy that if it was "lumpy" all the time, but it isn't. At a light it can be sitting there purring along butter smooth, but then all of a sudden it'll shudder for a second. Not enough shudder to be seen on the tach., but just enough to feel through the pedals and the seat. It's probably just me after leaving a buttery Honda V6. There's a whole lot more resipricating mass FROM a 5.7 L Detroit V8 vs. a 3.2 L Japanese V6.

  12. #12
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    Many of the Accords and TL's, RL's have either liquid or vacuum operated engine mounts that knock out the vibration. Should feel one with a bad mount. Talk about a rough idle.

  13. #13
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    Quote Originally Posted by Bobs05RT
    Many of the Accords and TL's, RL's have either liquid or vacuum operated engine mounts that knock out the vibration. Should feel one with a bad mount. Talk about a rough idle.
    Correct! The 01 Acura CLS I traded for the Magnum RT had liquid motor mounts. Other manufacturers should include this technology. I can tell you FROM personal experience that it works! I knew that Acura drivetrain was smooth, but I didn't know how smooth until I got this Magnum. That's not to say I don't love my Magnum. If I had to choose between the smoothness of the Honda and the torque of the Hemi I'll take the torque everyday and twice on Sunday!

  14. #14
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    I agree with Schmeky. I have a Honda Accord V6 which at idle is smooth as glass! Absolutely no vibration. On the other hand when I am stopped at a light with my RT, everytime it lurches it just keeps saying..... "hemi", "hemi", "hemi"..etc.... Gotta love it!!
    05 Mineral Grey Magnum R/T
    Hemi Registry # 00228



    SoCalLX - " Where Southern California Car Culture Meets Modern Mopar Muscle"

  15. #15
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    Very good points on the Acura/Honda hydraulic engine mounts. My wife's Acura is smoother at idle than the 5.7.

    I look at the Hemi kinda' like a Harley, the Honda as a . . well..er.. like a Honda. Honda's are refrigerator reliable and just about as exciting.

    The Hemi has a soul. Like a Harley. Personality. Uniqueness. Kinda raw. The mechanicals are slightly visceral. I like it.

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