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Prado 1KZ-TE Starting and Idling Problems

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  • Prado 1KZ-TE Starting and Idling Problems

    Hello everyone! I recently just joined the forum but have been reading posts since I acquired my 120 Prado. Iíve read all the posts that are relevant to my problem and have gone to the auto shop with the information and had repairs/inspections done accordingly but have had only negligible improvement.

    Hereís whatís wrong with my 120 (auto transmission):

    1. Engine turns but takes time to actually start. Weíve changed the fuel filter assembly & primer, the inlet air temp sensor, turbo sensor and crank position sensor. There have been improvements, but it still occurs intermittently. Sometimes it can go a whole day without problems, sometimes it acts up the entire day. There is a loud clicking sound coming from the engine when it turns too long. Have no idea what that is.

    2. Idle drops when the vehicle stopped, on drive with my foot on the brake, but only when the ac is on. It gets worse when when I turn the steering wheel, sometimes when Iím parking the engine actually dies due to the idle dropping so low. But switch the ac off and it idles fine.

    Mechanics have ruled out the fuel pump, injectors and heater plugs. Those have been inspected and everything is in good working order. Weíve also inspected the spill valve with a multimeter and the ohm reading is within spec.

    We are all dumbfounded, plugging in the diagnostic tool shows no error code. I desperately need your help guys!
    Last edited by jsbautista08; 27-11-2018, 06:21 PM.

  • #2
    When you say replaced fuel pump, is that the injector pump on the engine? I recall spill valves testing OK but playing up when hot, replacing it fixed the problem. Second hand one somewhere or borrow one to sub the original?


    • #3
      My apologies, I meant to say fuel filter. I should edit that


      • #4
        Rule out an air leak in the fuel line somewhere with a short length of clear hose between the fuel filter and the injector pump. Grab a couple of 3/8" barb fittings and make one of these up.

        Click image for larger version

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        Bleed the fuel line after fitting it and when the engine's running there should be barely any bubbles.
        Silver '04 KZJ120~Manual~GXL~Dobinson/Kings lift~Custom valved Ironmans~Detroit Locker~Endless Air~X9 Superwinch~Madman EMS1~TJM Dual Battery~Rhino Roof Tray~120W solar panel~Foxwing awning~Bushskinz UVP~Long Ranger water tank~Bushman fridge~Steinbauer P-Box~Beaudesert 2 3/4"~Airtec Snorkel~TJM Sliders~Prico Boost Gauge~BFG-KO2s~TPMS~GME TX3420~Front and Rear Cameras~Ultimate Camper hanging off the back!


        • #5
          adrian5800, that sounds like something I should do next. Will post back if that solves it.

          t303, might be tough as that particular part is only sold here with a brand new pump. Iím gonna try to source out a used one and see.

          Thanks for both both your recommendations, any more ideas are most welcome!



          • #6
            adrian5800 , we did the leak test and everything seems fine. Funny thing though, just by accident we accidentally forgot to reconnect the hose that goes from the MAP sensor to MAP filter and all of a sudden the Prado was starting fine! Connected the hose back to filter and the starting problem came back almost instantly. I canít for the life of me figure out how to proceed.

            We cleaned the filter and hoses with carb cleaner and thereís some improvement. Weíre still observing it, will post back a report.

            Any other suggestions?


            • #7
              Replace the Map Filter and chuck a scan tool on and see the MAP sensor is reading properly.


              • #8
                Originally posted by ejukated View Post
                Replace the Map Filter and chuck a scan tool on and see the MAP sensor is reading properly.
                This is definitely doable. What should the reading on the scan tool be? I've no idea what the proper spec is.


                • #9
                  Originally posted by jsbautista08 View Post

                  This is definitely doable. What should the reading on the scan tool be? I've no idea what the proper spec is.
                  around 100kpa with the engine not running but ignition on reds. as you drive you should see it register boost till about 10psi (170kPa abs) at full throttle.