Idle too fast on cold start

Discussion in '2.3 Engine' started by H.Dennis Hargrave, May 14, 2019.

  1. H.Dennis Hargrave

    H.Dennis Hargrave New Member

    I have a 2002 with the 2.3L DOHC 4 ,manual trans. without A/C. On cold start,it revs up to 2000/2500 rpm and then gradually slows to around 900 long before the engines warms up. The factory shop manual doesn't seem to provide any answers. I need to fix this ASAP. The truck only has 49,379 miles.
    Thanks in advance
    Dennis
     
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  3. Tonyroy1

    Tonyroy1 New Member

     
  4. Tonyroy1

    Tonyroy1 New Member

    My "94" Ranger 2.3 manual,no AC is the same....What,s the problem? So, it warms up fast & idles down....Why do you need to fix it ? Mine runs fine!!! What else is going on?? Sounds normal to me!!!!
     
  5. Tom Autry

    Tom Autry New Member

    My 2.3 does the same. It is computer controlled with an idle control valve. I don't think it is adjustable.
     
    Tonyroy1 likes this.
  6. Tonyroy1

    Tonyroy1 New Member

    Yeah...sounds normal to me..
     
  7. DeanMk

    DeanMk Member

    Does it rev up ANY TIME you take it out of gear (like when coming to a stop), even when the engine is warmed up, and then the revs suddenly drop, just before you come to a stop?
     
  8. OP
    H.Dennis Hargrave

    H.Dennis Hargrave New Member

    2000 to 2500 rpm seems dangerously high on an engine that is in the process of building oil pressure (start-up) especially with the ultra thin oil (5w-20). No other electronically managed engines that I've encountered rev this high on cold start-up. Sounds
    like a sure formula for very short engine life...not wanting to start any hostilities over this.
     
  9. DeanMk

    DeanMk Member

    Actually the opposite is true.
    In the old days, when my dad turned a wrench for the USAF, it wasn't unusual for an engine to have a low idle speed of between 400-500 rpm.
    He figured out that the lack of speed of such a low idle was causing the engine to run at too low of oil pressure and that was causing undue engine wear, shorting the TBO time.
    He turned up the idle on all of the engines he was in charge of to 600 RPM (which seemed unusually high in those days) and the engines lasted longer because they could maintain a more sufficient oil pressure.
    By the 1960's, a 600 rpm low idle speed had become pretty standard fare for all internal combustion engines.
    By the 1980's, the Japanese had enough R&D under their collective belts to garner an 800 rpm low idle for most of their engines and with Mazda, they actually figured that if you set the high idle very high (about 6000 rpm, from what I could figure) and run it for only a very short time (about 30 seconds), then the engine would kick down to its 800 rpm low idle and function fine because it had already attained sufficient operating tempreture.
     
    Last edited: May 21, 2019 at 8:16 PM

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