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Temperature Limits

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  • Temperature Limits

    G'day guys,

    Seems a lot of us are using a Scan Gauge or Torque to monitor EGT, ATF temp, DPF temp, TQ Converter temp and probably a few others. Question is what limits (soft or hard) are people looking for?

    EGT ?
    DFP Up to 600 deg seems normal during a burn?
    ATF 120 deg?
    TQ Converter 120 deg as well?


  • #2
    Personally don’t like ATF much more 100. After that it’s getting on the hotter side of things because Torque converter temps would be at least 20 deg hotter.
    EGT will vary depending on load but generally won’t go higher than 500
    Regens can go pretty high depending on need or if forced. But mine sit 580 to 650.
    One of my Toyota apprentices said he seen temps hit 900 on a bad DPF
    engine temp was about 86 if I remember correctly didn’t really go higher even under harder driving conditions


    • #3
      Towed the van in some decent headwinds today up and down hills. EGT sat around 450 unless it was working hard up a hill. Floored it got as high as 630! Might need an exhaust? Water temp got to 88. ATF got up to 110, TRQ Converter 125. Might need a tranny cooler too. Or a tent/landcruiser!


      • #4
        Transmission cooler works at treat, towed caravan for 5 hours today and really took a good chunk of heat out of it. At ambient temp of 20 deg trans pan temp sat at 66 and 76 when ambient temp hit 30 deg. Well worth the investment.


        • #5
          For sure. Wholesale Autos? I’ll have to see how I can get one sorted in WA... Wouldn’t mind one of their TQ lockup kits too...


          • Spook1205
            Spook1205 commented
            Editing a comment
            I tow in 4th too and drop in to drive occasionally when on decent unless I want some engine braking.

          • olvansta
            olvansta commented
            Editing a comment
            I would also be interested in a Perth installer. On a recent trip towing a 2.5T van with my crusade my tranny and torque converter temps were reaching 125deg. I don't know the alarm set point but 125deg is too high for my liking. I'll be towing Sydney in March so I think a cooler would be a wise investment

          • Spook1205
            Spook1205 commented
            Editing a comment
            Wholesale automatics may be able to recommend someone. But in reality if you know a mechanic that is reliable and you are happy with there work they could very easily do it.

        • #6
          Good tips. What’s the hardest part of the lockup kit Install? Splicing into ecu wires? I can’t see a link to a tranny cooler - I’ll give them a a call and see. Could have bought a 200 series after all these mods! I’ve been towing in s5 unless the tq converter is always slipping, in which case I’ll sit in 4th....


          • Spook1205
            Spook1205 commented
            Editing a comment
            Install kit talking about is oil cooler, sorry for confusion.
            Online it’s the 6 speed Toyota Hulu’s kit. Same same so to speak.
            As for lock up kit I haven’t put one in and probably won’t I guess.

        • #7
          Just checked my EGT tonight. Ran around 700 for a while then dropped to 650 cruising at 100kph . Stayed there from then on tll I got home regardless of speed. Bit strange. Any thoughts. Fuel timing now sits on _ minus 2.2 at idle and minus 3.4 cruising at 100kph. Under acceleration moves to a bit retarded to me. Wold this cause the high EGT or is it all normal?


          • #8
            I have never heard EGT1 being that high, although I have had it to mid 500 towing full load up a hill.

            if you are monitoring EGT2 after the catalyst it’s common on a regen. Regen temp is lower on highway too mate.

            The fuel timing looks normal. But will double check on Friday when I plug a techstream scantool and drive around this Friday to pull engine data under different driving conditions.

            As you probably are aware the system has tiny injection nozzle holes and high fuel rail pressure.
            Fuel would explode very quickly with the above design and piston needs to be after top dead centre when the fuel /air mixture expands very rapidly.
            we are used to seeing engines timed in advance because of the physical time it takes for the fuel to not just ignite but to rapidly expand.

            Fun fact-
            At 3,000 rpm you have 25 power strokes per second per piston
            A petrol doing 5,000rpm you have 41 power strokes per second per piston.

            cruising on highway at 1,800 rpm you have 15 of the above.

            ill get back to you Davidd on what I find with the fuel timing.


            • #9
              Could a blocked or partially blocked DPF cause these EGTs . Fuel economy also dreadful. Last regen was difficult. Long run followed by 10 mins on front lawn, followed by another short run followed by another 5 minutes on front lawn to clear it.


              • Spook1205
                Spook1205 commented
                Editing a comment
                Logically built up exhaust you would think would retain lots of heat.
                Last regen sounds difficult and drawn out especially with time on front lawn after long run ( if in regen for length of long run)
                Can you monitor DPF%?

                So putting the above information together with bad fuel consumption it would definitely be worth looking into as a probable cause of symptoms.

                A multimeter check on sensor would be a good indicator

            • #10
              Assuming the engine timing Fuel is correct, ( it idles at minus 2.2, cruises at minus 3.8. Under acceleration goes to about plus 4 deg. but varies of course.) all other basic engine read outs seem pretty right. Except for EGTs. While out today checked it again and cruising under light pedal it sat on 330 to 380 deg C. 562 to 652 deg. F. Fuel economy seems to be around 10.5 per hundred so far with another regen to come. This kind of driving in a manual should be approx. 8.5 per 100.
              Could the negative fuel timing and high EGTs be because it is in constant regen? Is it possible the 5th injector is permanently on for some reason. Any opinion welcome before I burn out the valves or the Turbo. it's getting to be a worry. Re DPF, for some reason the readout is pretty useless. Reads a constant minus 325 and varies up or down a couple of whatever the reading is. It's either been switched off or is a faulty sensor. Where is the sensor so I can check it please mate?
              Last edited by davidd; 07-02-2018, 02:38 PM.


              • Spook1205
                Spook1205 commented
                Editing a comment
                Davidd the sensor will put out a voltage, the ECU will use numerous things to come up with DPF% value. Things like fuel used, driving conditions and especially the DPF voltage most likely down to the millivolt scale cross referenced with engine load (MAF sensor, boost pressure sensor) to what voltage should be and what it is.
                This is logically what I believe from spending years working on, studying and teaching engine management systems. But sometimes I am wrong hey so open to learning and changing thought process if evidence is there. In other words it’s just my opinion.
                Last edited by Spook1205; 07-02-2018, 03:46 PM. Reason: Extra info

              • DaveC
                DaveC commented
                Editing a comment
                330 to 380 deg C and 10.5 per hundred sounds perfectly normal to me...

            • #11
              Originally posted by davidd View Post
              Is it possible the 5th injector is permanently on for some reason.
              if its an electrical issue , the only to check it is to wire in an LED ( with 560ohm resistor ) across the injector. if the LED is lit then power is being applied to it and its therefore open. another possible scenario is a leaking injector which may be stuck partially open , which will be much more difficult to diagnose.

              2019 GX , in White


              • Spook1205
                Spook1205 commented
                Editing a comment
                The DPF sensor is above the DPF and has 2 tunes going to it.
                Middle wire is signal wire, should be under 1.2v at idle preferably .8v
                Then rev the crap out of it max should go to is 1.5v under hard driving conditions 2v max. Under these max voltages less is a better scenario.

                With injector white One is most likely on the money with the resistor value. You just need to wire the resistor and LED across the two wires in parallel for injector. Reason being it is earth switched and always has power there. When earthed out the injector will use the voltage and you will have a voltage drop, then LED will work.
                If stuck on from ecu earth signal the LED will light up all the time. If injector is physically stuck open without injection earth signal then only way to test that is to look for the pintle hump caused by the injector pintle dropping through the injector solenoid and you need a decent oscilloscope to do this.
                But I think look at DPF blockage first.
                I put a video up about DPF sensor.

            • #12
              Some pics for reference


              • #13
                Thanks, did you go for a drive and check the EGTs as you intended or get caught up with other things mate?


                • Spook1205
                  Spook1205 commented
                  Editing a comment
                  At operating temp my EGT1 (before catalyst) at idle sits at about 250deg this will go as high as high 400’s under load and if towing up long big hill I got it to about 560 - 580 once.

                  EGT2 measures the temperature after catalyst this will mimic EGT1 unless under regen then can be 200 plus degrees hotter than EGT1.

                  Diesel is injected before turbo to ensure maximum fuel vaporisation and mixing. Once the hydrocarbons (fuel) hits the catalyst there is an oxidation effect and huge amount of heat is formed. This goes straight into DPF.

                  Not sure what you are monitoring the EGT with and I am hoping it’s accurate.

                  If you think you have a DPF issue can you get two bits of info for me
                  - how many kms are you getting before each regen?
                  - what is the voltage out of DPF pressure sensor?

                  A scangauge2 is an awesome piece of equipment and is worth the investment.

                  From there we can start to make a better judgement
                  Cheers, Luke

              • #14
                My regen started again. Picked it up as I noticed engine speed pick up at idle when I stopped at lights. Drove 5 km by the time I got home and it was still going. Parked it on front lawn and let it go, After 1bout 15 minutes the regen finished. During the regen the highest egt readout was 700 deg. C. Bloody hell. Others up to 500. After regen temps at idle were from under 200 to 230 deg. C. When driving still from 320 to 360 deg. C. Pretty high. 680 deg. F cruising on the flat no load, no regen. All engine parameters normal. Injector readout not available with this scanner. DPF readout doesn't work. Starting to look like a DPF thing. Partially blocked Dpf could keep the egts up if i understand what you said earlier. Forget last regen time, but no moe than 200km ago, not good. Interesting is that during this stationary regen the fuel timing was retarded to minus 34 degrees. What I have noticed is missing is that burning rubber smell that used to be there.
                Last edited by davidd; 08-02-2018, 12:24 PM.


                • #15

                  My experience is that once you park (stop driving), the burn may continue for a little while but it will *not* complete (unless it was near completion anyway). It will just stop, and resume next time you drive. This is much easier to observe if you can program the DPF% into your scan tool. It's not clear what sensors you are monitoring and how, and you are swapping between F and C temps. I'm not actually convinced you have any sort of problem! Is there some kind of outward symptom (e.g. smoke) or are you just not happy with what you are seeing in the scan tool?