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Thread: Cold idle RPM gems V8

  1. #1
    Join Date
    Jan 2016
    Location
    Netherlands
    Posts
    243

    Cold idle RPM gems V8

    Hi all,

    I've been having this problem that my engine usually want's to nearly stall if I try to move the car just a few meters when cold and in various other circumstances. I suspect the idle valve but am not sure how to test it. The first thing that came to mind is that nearly all vehicles I own or have owned have a high idle when cold, that is to say higher then when warm. My V8 has never had a high idle. not even when around the arctic circle at around -30c it's always 650-750 rpm. I thought that was because the V8 with the power strokes so close to each other simply does not need it but perhaps my car is simply broken but I never really noticed

    So how do your P38's idle when cold?

    -P

  2. #2
    Join Date
    Feb 2010
    Location
    Townsville, QLD
    Posts
    2,511
    Mine is a Thor, itíll sit up around 1,100rpm for maybe 30sec before settling down to 700rpm. Some GEMS ones Iíve worked on have been similar. The warm idle on GEMS seems to be a bit lower, around 600 to 650rpm.

    I think yours is special! It should still do the magic high-idle when cold though. Perhaps the IACV needs attention?

    Cheers
    Keithy

    Green 2000 P38 Range Rover HSE - Gone
    Blue 1999 P38 Range Rover HSE - Gone

    Silver 2002 P38 Range Rover HSE - Sequential LPG, BCDC Charger, TPMS, Rear Locker, Wheel Carrier, Bullbar & Spotlights, General Grabber AT2's, Too Much to Mention!

  3. #3
    Join Date
    Jul 2014
    Location
    Sydney
    Posts
    670
    My Thor is the same as Keithy's.
    2000 4.6 HSE Alveston red
    2007 307 xse peugeot
    1974 xj6l jaguar

  4. #4
    Join Date
    Jan 2016
    Location
    Netherlands
    Posts
    243
    @keithy, do'nt let my car hear that! It want's enough special attention as it is haha

    In any case, I think it is about time I took that thing apart, yes. I'll do some searching around ofcourse, but does anyone know the best way to test these?

    Cheers,
    -P

  5. #5
    Join Date
    Apr 2009
    Location
    Crafers West South Australia
    Posts
    11,333
    Have you adjusted the base idle speed up? This is done by the screw set into the top of the throttle body area. If it is set too low the IAC will not be able to raise the idle speed very far when cold. Conversely when the base idle is set too high the IAC won't be able to drop the engine back to the correct idle speed on a hot engine.

  6. #6
    Join Date
    Jan 2016
    Location
    Netherlands
    Posts
    243
    bee utey, I have not touched the idle speed but thanks for the tip I did take the throttle body apart to replace the o-ring since it was sucking in air there but I did not touch any of the adjustments... Might be worth a look when I get the IACV replaced.

    Speaking of which, I tried to take that thing apart and boy what was LR thinking. M4 bolts with locktite?! Ofcourse mine had been in there for 20 odd years and the first gently twist snapped the head clean of. If I leave al the nsfw words out, I did not say a lot...

    Anyway! After a couple of hours trying to get the snapped of bolt out, rethreading both holes, new bolts etc. I could finally get to work on the iacv. It was dirty so I took a wirebrush drillbit to it and... I unscrewed the centre pin. Ok I thought, good thing since I can get to cleaning the bloody thing a lot better. Got it nice and clean and smooth and removed some of the old hard grease and replaced with something fresh. I got the pin to move though with quite some resistance. Tried taking it apart again but to no avail. Pushing it further in was really hard too and since I did not want to break the bloody thing I just tested it out on the car. The idle speed was up instantly to almost 2krpm. I gave the computer and IACV some time to settle down but after a few minutes I could see the computer (faultmate) reduce the amount of steps to about 120 but nowhere near the 20 I've seen here and there. I doubted the IACV was doing it's job so I took it out once again and tried more force to get the pin to move. Something said snap and after that there as movement in the pin though I doubt it is still functioning as intended

    Seeing as a replacement is around $25 down here I simply ordered a new one and will pick this back up once that comes in.

    Cheers,
    -P

  7. #7
    TheTree is offline ChatterBox Silver Subscriber
    Join Date
    Feb 2013
    Location
    Gosford, NSW, Australia
    Posts
    2,500
    Hi mate

    Sadly I think your IVAC is toast, it says in RAVE not to push or pull the center shaft while cleaning it

    Steve
    MY96 4.6 HSE P38. Niagara Grey; "The Phoenix"
    MY99 4.6 HSE P38. LPG, Blenheim Sliver; "Voldemort" burnt to a cinder
    MY79 RR Classic, Gone, MY57 Series 1 SWB, Long gone
    P38 write ups and info on my website http://p38.hts.com.au/

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