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Pre-heat/glow plugs timer question for 92 2.4 turbo D

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  • Pre-heat/glow plugs timer question for 92 2.4 turbo D

    Maybe somebody can help me here.

    I have a problem with lumpy idle/no power just after startup. This condition lasts only for about 30 secs, but then goes away and the car drives fine after that. Now its summer (though at the moment that means that the rain is warmer) in Blitey, and I worry what it will be like as the days turn cooler.

    So

    I have done a little research and I will tell you what I have checked.

    Individually tested top glow plugs resistance OK (all less than 1 Ohm)

    Struggled to check the glow plug resistor (manifold heater) so not sure that is OK but read on.

    Checked for volts being applied to the top plugs, OK. A period of 11 Volts followed by a longer period with lower volts (doesn't that mean the glow plug resistor is OK since it goes in series for the afterglow period with the top plugs).

    My question is about the temperature sensor screwed into the block below the rearmost inlet manifold junction. The book talks about testing it and it shows (in the Haynes) somebody using an Ohm meter on it. However, they are having a laugh since its nigh on impossible to get at.

    However

    This sensor must be cabled back to the heater timer control relay in the saloon (isn't it?), so surely I should be able to measure it from there.

    But

    There is no circuit diagram with the timer relay (though the Haynes manual does show some fault finding/testing).

    so

    Does anyone have a circuit diagram for the full pre-heat system, or at least knows what the connections are for the multiplug that goes onto the timer relay. Oh and just for fun, the Haynes shows 3 variants on the timer relays.
    Anyway my car is a 92 2.4 ssrx Turbo D.

    Cheers... Rob.
    Red to Red, Black to Black, Blue to bits!

  • #2
    You could have dribbly injectors. (Not spraying properly so they're dribbling into a cold engine and the glowplugs can't heat the fuel sufficiently)

    Try some injector cleaner in the tank or better still, the next time you re-new the fuel filter, fill it with injector cleaner before re-fitting.

    Comment


    • #3
      Originally posted by ro80rob View Post
      This sensor must be cabled back to the heater timer control relay in the saloon (isn't it?), so surely I should be able to measure it from there.
      The Coolant sensor is connected to THW and E2 of the ECU. I suppose resistance could be checked from there, providing the wiring to the sensor is ok. If doing it this way then I guess it would need checking cold and at various stages of engine warm up.

      http://www.offroadpakistan.com/downl...hermistors.pdf

      Nev

      Comment


      • #4
        Out of interest, are you by any chance running on cooking oil? I had exactly the same symptoms on cooking oil. Biodiesel is ok as is ordinary diesel of course, but I get the same symptoms with any more than about 15% cooking oil. Ironically, if I add some bio diesel it seems a lot better on cooking oil and will run a much higher amount of cooking oil without a problem.

        Comment


        • #5
          OK

          A little further discussion on this if you please.

          I haven't looked into the dribbly injector question yet, so that is still out there as a possible.

          That aside..

          The thing starts perfectly. If I wait for the light to go out, or the buzzer to sound, it starts just the same. A1 first turn.

          But..

          The length of time the heater light comes on for is definitely shorter than it was, though if I check with my DVM, the juice stays on high (11V) for several seconds more, then drops to a lower level after a click is heard. The buzzer sounds a little later on still, but the juice remains on the heaters. Oh and I checked all the heaters and connection. All are fine.

          Questions are:-
          Can the heaters stay on too long?

          I'm not sure if the information found at the link given by 'NiftyNev' is for the petrol engined cars as a number of the drawings in my 'Haynes Toyota Hilux & 4-Runner (Diesel)' manual show this water temp sensor connected to the glow plug timer relay. Could this be correct?

          However

          My other thought is that this sensor fulfills two functions, maybe it controls the glow plug times and also tells the EFI the water temperature.

          So..

          If I am convinced that the glow plug light is on for a shorter time, maybe it is telling the truth (I know its always hard to believe the instrumentation, and I work in instrumentation) as it sees it. It is 'reporting' that the engine is at virtually normal operating temperature, and so the engine starts with its 'warm engine' settings in the EFI, so it really doesn't want to drive off until its had 40 seconds or so of running (using the idle-up switch), after which it is fine and drives perfectly.

          Also (out of curiosity)

          What does the EFI do when the engine is started from cold (and all is working correctly). Do diesels need more fuel or is it that the timing changes in some way (if that causes a different effect).

          Any ideas on any of the above points would be interesting. However, if it is this sensor, I would need a very special person who knew how the heck you change this part. It looks impossible. Is it an injector pipes off/starter out job?

          Cheers... Rob.
          Red to Red, Black to Black, Blue to bits!

          Comment


          • #6
            Oh

            And I use nomal from the pumps (very expensive) diesel.

            Cheers.
            Red to Red, Black to Black, Blue to bits!

            Comment


            • #7
              IIRC, the preheat time decreases as ambient temperature increases. I'm thinking you're looking too far into a problem that may not be there, mine is always lumpy at start up.
              Do you know that, with a 50 character limit, it's

              Comment


              • #8
                Mine has the same symptom - 30 secs or so a bit rough and then sweet as a nut. No different last winter and definetly not worse in the winter.
                Seems youre devoting a lot of time and effort to a very minor issue, after all the motors over 15 years old....
                私のホバークラフト は鰻が一杯です。

                Comment


                • #9
                  And just one more bit of info.

                  I followed NiftNevs instructions on getting the fault codes

                  See...

                  http://www.hiluxsurf.co.uk/forums/sh...130+fault+code

                  I got two flashes then after a period 8 flashes on the engine check light.#

                  By Nev's list, this tells me I have a faulty Turbo Boost pressure sensor (wherever that is) and a faulty Intake air temperature sensor.

                  As to taking this to the Nth degree, my niggle (and you are right, it is I suppose a niggle) is that I have spent a reasonable sum in having a new head, and before that was replaced, the thing ran perfectly, and I just kinda wanted that back. The thing does run perfectly but I wanted it to be the start and go car it was before.

                  However

                  If the fault codes do add up (certainly the air temp sensor), I can easily replace that and see how I go I guess. I really wasn't going to get to that water temp sensor was I? Its just too difficult to get at.

                  Cheers... Rob.
                  Red to Red, Black to Black, Blue to bits!

                  Comment


                  • #10
                    Check they're wired up right. They are reasonably close to each other, maybe they've got their wiring muddled up.

                    Does your turbo boost light come on ok?
                    Do you know that, with a 50 character limit, it's

                    Comment


                    • #11
                      Make sure both sensors have the plugs connected and the Turbo Sensor hose is connected to the manifold.

                      Clear codes and retest to see if they reappear.

                      Nev
                      Attached Files

                      Comment


                      • #12
                        Hello Nev

                        Thanks for that. I've checked the connections and all look OK.
                        I've checked the resistance of the air intake thermister, and that was about 800 Ohms, which is fair enough to my mind, as the car had been stopped for some 45 mins after a run and heat soak had meant the air filter had warmed through. I also measured back up the cables into the ECU. That was about 2.9k Ohms. That seems reasonable enough to me to prove it is connected to something and not grounded (short) or open circuit.

                        I don't know how to check the turbo pressure sensor, but I did pull the plug off, and checked it over. It all seemed fine. The turbo light does come on and at the same sort of load that it used to. Is that fed from this sensor or a switch within there?

                        How do I clear the fault codes and what do I do after it to get the system to re-check its sensors. Do I have to start and run it after I clear the codes or can I just ask for fault codes again.
                        I can understand the code for the air temp sensor as the car was most likely run with the air filter off after initial start up following the head job. I can't see any reason why the turbo pressure sensor would fail though, unless it is just old age.

                        Cheers... Rob.
                        Red to Red, Black to Black, Blue to bits!

                        Comment


                        • #13
                          Read this thread. It has some useful info on the Turbo Pressure Sensor.

                          http://www.toyotasurf.asn.au/forum/v...ic.php?t=17676

                          Disconnect battery/s to clear codes. Retest before driving to confirm system normal and retest again after being driven. I think you may be getting a Turbo Sensor fault code because the vehicle may have been started and.or driven while it was unplugged.

                          Nev

                          Comment


                          • #14
                            Hello Nev

                            Right. I disconnected the battery and left it that way for about 15 mins.

                            I re-connected and did the code test straight away. I get a code 1, which seems to be 'normal'. I then ceased the code test and started the car and ran it for a couple of minutes (no driving). I then did a re-test and again got a code 1.

                            I guess this is good news.

                            One more question, with a fault code stored, does the ECU continue to disregard the sensors that are 'at fault', until the code is cleared, or does it start to use them if they appear to be working on next startup.

                            Cheers... Rob.
                            Red to Red, Black to Black, Blue to bits!

                            Comment


                            • #15
                              Codes ar stored and will continue to illuminate the check light until cleared. System normal will remain until the ECU again detects a fault. Retest after you have driven the vehicle and let me know the results.

                              Nev

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