Won't rev over 4500 rpm

Discussion in 'General Discussion' started by MDA, Sep 25, 2012.

Car Parts
  1. MDA

    MDA Full Access Member

    Messages:
    66
    Likes Received:
    1
    Joined:
    Aug 13, 2012
    I swear I have a vacuum leak. I was looking around to try and find any hose issues. Didn't see any. Started her up. Rev and it only goes to 4500. I know that it's throwing a P0420. Would that actually cause limp mode?
     
  2. VPRPWRD

    VPRPWRD VTCoA Ring Leader Supporting Member

    Messages:
    10,836
    Likes Received:
    10
    Joined:
    Mar 28, 2012
    Location:
    PA
    clogged catalytic converter
     
  3. hawk02

    hawk02 Full Access Member

    Messages:
    3,112
    Likes Received:
    1
    Joined:
    Jun 18, 2012
    I think that with no load on the motor/free rev it limits it at 4500rpm, how is it driving, if you get on it will it go over 4500????
     
  4. MDA

    MDA Full Access Member

    Messages:
    66
    Likes Received:
    1
    Joined:
    Aug 13, 2012
    Forgot to mention I have no cats. :)

    Havent tried it while driving yet.
     
  5. VPRPWRD

    VPRPWRD VTCoA Ring Leader Supporting Member

    Messages:
    10,836
    Likes Received:
    10
    Joined:
    Mar 28, 2012
    Location:
    PA
    Do you have the o2 cheater harnesses on? P0420 is catalytic converter efficiency code, could also be a bad o2 sensor giving the PCM a false reading.
     
  6. MDA

    MDA Full Access Member

    Messages:
    66
    Likes Received:
    1
    Joined:
    Aug 13, 2012
    Just cleared the 0420. Still doesn't rev over 4500. I'll try it under load in a little while.
     
  7. VPRPWRD

    VPRPWRD VTCoA Ring Leader Supporting Member

    Messages:
    10,836
    Likes Received:
    10
    Joined:
    Mar 28, 2012
    Location:
    PA
    Let us know what happens when you drive it.
     
  8. hawk02

    hawk02 Full Access Member

    Messages:
    3,112
    Likes Received:
    1
    Joined:
    Jun 18, 2012
    I think I may have it mixed up with my old 05 Hemi, that had a 4500 limiter in park and "N", not sure if Dodge did it with these trucks, but I wouldn't want to free rev it over that anyway......
     
  9. MDA

    MDA Full Access Member

    Messages:
    66
    Likes Received:
    1
    Joined:
    Aug 13, 2012
    As far as I know, I do not have that. Truck was bought with these MODs.
     
  10. VPRPWRD

    VPRPWRD VTCoA Ring Leader Supporting Member

    Messages:
    10,836
    Likes Received:
    10
    Joined:
    Mar 28, 2012
    Location:
    PA
    Have you had it for a while or did you just recently purchase it?
     
  11. MDA

    MDA Full Access Member

    Messages:
    66
    Likes Received:
    1
    Joined:
    Aug 13, 2012
    Just drove her and went past 4500. Guess it is limited when in park.

    I've had it for about a month.
     
  12. VPRPWRD

    VPRPWRD VTCoA Ring Leader Supporting Member

    Messages:
    10,836
    Likes Received:
    10
    Joined:
    Mar 28, 2012
    Location:
    PA
    Well that's good to know, did the p0420 come back?
     
  13. MDA

    MDA Full Access Member

    Messages:
    66
    Likes Received:
    1
    Joined:
    Aug 13, 2012
    Yes it did.
     
  14. VENOMOUS1 RACING

    VENOMOUS1 RACING Has Left the Room - Banned from VTCOA!

    Messages:
    12,751
    Likes Received:
    2
    Joined:
    May 15, 2009
    Location:
    Wacko Waco,TX
    Bad O2 sensor! Does it have a tuner? sCT handheld? Does it have O2 simulators on rear O2s?
     
  15. hawk02

    hawk02 Full Access Member

    Messages:
    3,112
    Likes Received:
    1
    Joined:
    Jun 18, 2012
    Nice to know, same as my old Dodge Hemi truck. I finally knew the right info!!! LOL
     
  16. VPRPWRD

    VPRPWRD VTCoA Ring Leader Supporting Member

    Messages:
    10,836
    Likes Received:
    10
    Joined:
    Mar 28, 2012
    Location:
    PA
    You definitely need to get o2 sims on the rear o2 sensors, but at least it sounds like your revving "problem" isn't really a problem at all.
     
  17. MDA

    MDA Full Access Member

    Messages:
    66
    Likes Received:
    1
    Joined:
    Aug 13, 2012
    Thanks for all the replies everyone. :)

    About the o2 problem... I do not have a sct. I need to get one. If I get the sct will I still need the sims?
     
  18. VENOMOUS1 RACING

    VENOMOUS1 RACING Has Left the Room - Banned from VTCOA!

    Messages:
    12,751
    Likes Received:
    2
    Joined:
    May 15, 2009
    Location:
    Wacko Waco,TX
    No but you'll need to have good O2s there, they are just tuned out. Could very well be a front O2 acting up which fuel the engine correctly.