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Thread: Random Performance Issue - After Warm Up

  1. #1
    Join Date
    Jul 2010
    Location
    Ripon, Ca. (That's not England chaps)
    Posts
    1,514

    Random Performance Issue - After Warm Up

    It's been a long time since I've been on LRRForms. Anyway, I'm still enjoying my LR. Well, not so much for the past month.

    I've had several mornings where the engine starts missing (always about 5 miles from home) when the engine gets warmed up. The stumbling comes on suddelly, getting worst were it won't rev about 1500 rpm in neutral. After a couple minutes, it will gradually allow revs faster and faster until like magic... It runs like the problem never happened. No codes until today it threw a P1316 (likely because of the revs I was doing to inspect the recovery process). The CEL cleared so I think it was just a byproduct of the problem.

    Could this be the Crank Positioning Sensor going out? Why does it only happen when transferring from cold engine to warm? A sticking warm up circuit?

    Bill of Green Achers Farms
    Adventure for fellow Geeks! Geocaching
    Land Rover Repair Manual - Download Site
    1. 1996 Discovery I - Yet to be named
    2. 1998 Discovery I - "Kermit"
    3. 2000 Discovery II - Parts Donor


  2. #2
    Join Date
    Mar 2010
    Location
    Lake Villa, IL
    Posts
    449
    See what your O2's are doing. I use a Bluetooth dongle and the TorquePro app. Could be you have a bad O2. The ECU might see it as "working" only in that its getting a signal and therefore not throw a code for it. But that signal could be all out of whack.
    I had an O2 do that after I spliced it, poorly. I fixed the splice with a proper solder joint. It fixed the problem for a couple days but then I had a misfire on Cly 4 from a fouled plug, probably as a result of wonky O2 readings and improper fueling.
    Changed the plugs using Champion Coppers gapped to .045 and everything has been beautiful for a few days now.

  3. #3
    Join Date
    Jul 2010
    Location
    Ripon, Ca. (That's not England chaps)
    Posts
    1,514
    Well, I decided to guess/change the Crank Position Sensor after reading several comments floating on the internet. Haven't had the problem since so I think it's resolved.

    After a week of watching the good results, I invested in new custom ignition wires... WOW! What an improvement. It took a while to do all the measuring, cutting, splicing, installing, but I've been rewarded with an engine that woke up.
    Then on New Years Eve, my wife had to take an emergency trip into the Sierra's. The head lights faded, then the SRS light came on, then the engine started stumbling (in a new way), then it quit (in spite of her not stopping). Turned out to be a dead alternator. Replaced it today and everything is great again. Also corrected my fan belt routing that's been running the water pump and fan backwards for the past year (when I replaced the belt). Man was that a stupid mistake that's plagued me since I installed it. But that's another story.

    Bill of Green Achers Farms
    Adventure for fellow Geeks! Geocaching
    Land Rover Repair Manual - Download Site
    1. 1996 Discovery I - Yet to be named
    2. 1998 Discovery I - "Kermit"
    3. 2000 Discovery II - Parts Donor


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