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Thread: Jag X300 hard tp start and stumbling when pulling away

  1. #1
    Member Freebird's Avatar
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    Jag X300 hard tp start and stumbling when pulling away

    Hi all.

    My 3.2 has done 165000 miles now and has recently developed the faults in the title.

    I don't use it as much as I did since retiring so it can sit for a couple of weeks between runs. the first issue is that it has become difficult to start. It will fire then die several times before eventually chugging into life.

    Once running it idles ok, but when I accelerate, it dies and will stall unless I am very gentle with the pedal.

    My initial thought is a duff throttle position sensor, but am keen to see what others think - cheap they are not. I have cleaned the idle control valve (because that is more accessible) to no effect.

    Thanks in anticipation

    Glen.
    1996 X300 3.2 LPG, so cool.
    2005 BMW 330d Snore.......
    1969 Triumph Vitesse convertible

    1974 Suzuki GT550
    2000 Triumph Speed Triple 955i
    Merstham, Surrey.

  2. #2
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    Quote Originally Posted by Freebird View Post
    Hi all.

    My 3.2 has done 165000 miles now and has recently developed the faults in the title.

    I don't use it as much as I did since retiring so it can sit for a couple of weeks between runs. the first issue is that it has become difficult to start. It will fire then die several times before eventually chugging into life.

    Once running it idles ok, but when I accelerate, it dies and will stall unless I am very gentle with the pedal.

    My initial thought is a duff throttle position sensor, but am keen to see what others think - cheap they are not. I have cleaned the idle control valve (because that is more accessible) to no effect.

    Thanks in anticipation

    Glen.
    Have you cleaned the Throttle Body itself? Those tend to gum up on the inside.

    How about the MAF? Some MAF Cleaner spray might do the trick.

    Both are cheap fixes to common problems with these engines. I'm thinking its the throttle body. Take it off the car and clean it from both ends. Trying to clean it in place leaves the TPS in a vulnerable position as any cleaning fluids you decide to use, could enter the sensor and destroy it....assuming that it's not the problem already.

    After that, I might suggest spark plugs and coils.

  3. #3
    Member Freebird's Avatar
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    Quote Originally Posted by Vee View Post
    Have you cleaned the Throttle Body itself? Those tend to gum up on the inside.

    How about the MAF? Some MAF Cleaner spray might do the trick.

    Both are cheap fixes to common problems with these engines. I'm thinking its the throttle body. Take it off the car and clean it from both ends. Trying to clean it in place leaves the TPS in a vulnerable position as any cleaning fluids you decide to use, could enter the sensor and destroy it....assuming that it's not the problem already.

    After that, I might suggest spark plugs and coils.
    Thanks for the suggestions - all very valid. I will have a go over the weekend and report back.

    Cheers

    Glen
    1996 X300 3.2 LPG, so cool.
    2005 BMW 330d Snore.......
    1969 Triumph Vitesse convertible

    1974 Suzuki GT550
    2000 Triumph Speed Triple 955i
    Merstham, Surrey.

  4. #4
    Member Freebird's Avatar
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    Today the car started and ran fine which is typical as I had not done anything to fix the problem.

    I removed the TB and cleaned everything up thoroughly including the MAF. I removed the throttle position sensor to avoid flooding it with carb cleaner and used a multimeter to try to see whether it's dead or not. I think it is because it's open circuit between all three terminals except at nearly fully open when there is a resistance between two of them. At wide open, it's open circuit again.

    I put it all back together and it ran a bit rough to start with and now idles at 1500rpm in park and neutral but drops to 900 in drive.

    Answers on a postcard please.

    Cheers

    Glen
    1996 X300 3.2 LPG, so cool.
    2005 BMW 330d Snore.......
    1969 Triumph Vitesse convertible

    1974 Suzuki GT550
    2000 Triumph Speed Triple 955i
    Merstham, Surrey.

  5. #5
    Member Freebird's Avatar
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    Hi All, I thought I would let you know that I cured my problem in case it's of use to anyone else.

    I fitted a thoroughly cleaned second hand throttle body complete with TPS and IAC valve and it made no difference, I then fitted a second hand MAF and that too made no difference. The previous owner had already fitted a new coolant temperature sensor so it was only a couple of years old, however I still had the original one, so I fitted that and all my problems went away.

    A bit annoying that I spent quite a bit of time and money chasing the problem around when I already had the solution in stock which took all of 3 minutes to fit, but you live and learn...

    Cheers

    Glen.
    1996 X300 3.2 LPG, so cool.
    2005 BMW 330d Snore.......
    1969 Triumph Vitesse convertible

    1974 Suzuki GT550
    2000 Triumph Speed Triple 955i
    Merstham, Surrey.

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