Hard cold starting and idling
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Thread: Hard cold starting and idling

  1. #1
    FRESHMAN ROVER
    Join Date
    August 20th, 2012
    Location
    Maine
    Posts
    6

    Hard cold starting and idling

    I'm sure these kind of questions come a-dime-a-dozen, but I was hoping someone may have some insight as to starting/idling on my '95 County. Sometimes (though not all the time) on cold days/nights, I'll go to start her and it will fire, but it will start running as if it's on 6 or 7 cylinders. If I rev it up a bit (past 1000rpm) it will suddenly be fine for a minute, but if I let my foot off, the engine goes back down to idle speed and runs very rough, chuggy-like. It generally doesn't stall, but it has twice before. Of course, running rough when cold is nothing alien to a slightly old British automobile, but it's as if the computer isn't adjusting idle-speed for the cold temperature. If it's still cold and in park, the computer will rev the motor up and down in cycles (between 700-1500 rpm). Even after letting it run for a bit before setting off, it will idle at stop very rough, and I have to stab the throttle a bit to get it take off. After it fully warms to temp though, it has always ran completely fine.

    Does any of this sound familiar to anyone? Is this just a characteristic of all 3.9's on cold startups, or is there some issue here?

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  3. #2
    FRESHMAN ROVER
    Join Date
    July 10th, 2011
    Location
    RRC @ North Washington State Coast, P38 @ Northern New Mexico
    Posts
    40

    Re: Hard cold starting and idling

    Hey, I'm 100% unskilled, but there is at least one known issue with the cold stalling symptom, but I can't recall what it is. My Classic used to stall at the same darned intersection every winter morning until my mechanic finally remembered said issue. I'd ask you about codes, but I wouldn't know what to tell you about them if you had any. I do have a underinformed understanding that, for a '91, the coolant temperature sensor affects cold starting as far as the amount of fuel it gets per different temperature conditions, so you could try replacing yours, but i think that it should have thrown a code if it was bad (& some of them break off down in there during removal attempts, so be careful). That's all I've got, but at least your thread got bumped? And did you check out the "Remedies" page? Range Rover Remedies
    '91 RRC SWB w/4.6 swap
    '99 P38 4.6 HSE

  4. #3
    FRESHMAN ROVER
    Join Date
    July 4th, 2011
    Posts
    188

    Re: Hard cold starting and idling

    From what Ive read on this forum, start with stepper motor and/or coolant temp sensor as Horse stated.
    Illinois,USA
    '85 Classic 3.5L
    '89 Classic 3.9L (sold)
    '00 Mercury Villager
    '64 John boat (it still leaks)

  5. #4
    FRESHMAN ROVER
    Join Date
    June 10th, 2006
    Location
    Gloucester, UK
    Posts
    69

    Re: Hard cold starting and idling

    As said previously, start with the stepper motor it's easy to extract and clean /lubricate. That may cure it, but the bit you said about it sounding as though it's starting on 6 or 7 cylinders was what happened to mine just before the head gasket went. When I investigated, the spark plugs were damp with coolant casing the misfire.
    Ex 22SAS, 3.9 Vogue SE '95

  6. #5
    FRESHMAN ROVER
    Join Date
    August 20th, 2012
    Location
    Maine
    Posts
    6

    Re: Hard cold starting and idling

    Update:

    I've noticed that there seems to be a very direct correlation with humidity and these starting/running problems. Last week I drove it almost every day, and the only day that there were any problems was when it was foggy and humid out. I started it up, did the strange chugging and revving up and down in cycles, but once the engine came to temperature, it idled just fine.

    The other problem it had on this day (and on other days when it starts badly) is that the motor seems to misfire at high rpm's when accelerating quickly. Example: I was getting on the highway, doing ~30 mph, and I had to get up to 60. Naturally, I gave it some stick; probably gave it about 75% throttle. It downshifted, started accelerating, but after about 4000-4250 rpm, it seems to misfire: It's somewhat hard to explain, but it's almost as if the motor loses spark and shuts down for a split second. It will start revving up and then make a weird "thunk" sound and stop for just a moment, and if I'm still giving it throttle and trying to speed up, it will do it repeatedly.

    Once again though: it only has these starting and running problems on CERTAIN days, not ALL THE TIME. I have noticed though that those certain days generally seem to be one's where it's quite moist/humid/wet. I thought maybe it was spark plug wires, but if it was, wouldn't it have running problems all the time, even after the engine came to temperature (because after coming to temperature, the motor will run just fine between 0-4000 rpm, it's only when I'm really trying to speed up and it revs past 4000 that it does the weird misfiring thing).

    Any input would be MUCH appreciated.

  7. #6
    FRESHMAN ROVER
    Join Date
    August 20th, 2012
    Location
    Maine
    Posts
    6

    Re: Hard cold starting and idling

    Bump anyone?

  8. #7
    SOPHOMORE ROVER
    Join Date
    February 6th, 2009
    Location
    Penn Hills, Pennsylvania
    Posts
    342

    Re: Hard cold starting and idling

    i dought if humidity is the problem , but it could be pcv hoses clogged , if its not stepper motor

  9. #8
    FRESHMAN ROVER
    Join Date
    July 4th, 2011
    Posts
    188

    Re: Hard cold starting and idling

    Odd ball experience...yrs back had ole ford e250 van, 351w...'78 to be exact. Would have to dry distributor out with hair dryer on damp/foggy days (of course with cap off). Finally found small crack in base (not cap) that was letting moisture in....
    Illinois,USA
    '85 Classic 3.5L
    '89 Classic 3.9L (sold)
    '00 Mercury Villager
    '64 John boat (it still leaks)

  10. #9
    FRESHMAN ROVER
    Join Date
    August 20th, 2012
    Location
    Maine
    Posts
    6

    Re: Hard cold starting and idling

    I think I'll finally be taking it in at the end of this week. Today for the first time it decided not to start. It tried to fire a few times, one time it got very close, but it wouldn't quite fully start. Snowing like hell out, so obviously the humidity/moisture was there.

  11. #10
    FRESHMAN ROVER
    Join Date
    July 4th, 2011
    Posts
    188

    Re: Hard cold starting and idling

    Please post what the "fix" was...
    Illinois,USA
    '85 Classic 3.5L
    '89 Classic 3.9L (sold)
    '00 Mercury Villager
    '64 John boat (it still leaks)

  12. #11
    FRESHMAN ROVER
    Join Date
    July 18th, 2010
    Location
    Las Vegas Nevada USA
    Posts
    176

    Re: Hard cold starting and idling

    My 90 will run rough as described until the alternator (or power relay?) kicks in and lights up he dash. Sometimes as long as thirty seconds in the cold. Revving it up seems to help.

    I also wonder if you have weak sparkplug wires tracking to ground when dampish?

  13. #12
    FRESHMAN ROVER
    Join Date
    March 27th, 2013
    Location
    Elizabethtown, PA
    Posts
    5

    Re: Hard cold starting and idling

    Looking through the maint history on my recently purchased '95 RRC 4.2L, it had a similar issue and was solved by using a hotter spark plug. Instead of the Champion RN11YC, used a RN12YC...no cold start, idling issues.

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