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MAF sensor and bushfires

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  • MAF sensor and bushfires

    Well I spent a couple of weeks up at Noosa and avoided the bushfires.
    Before I left I serviced the Tuna, changed all filters, cleaned MAF sensor and reset learning values from the Air/ fuel ratio sensor. Vehicle performed as expected with good fuel and economy and performance all the way up.
    Then nearly 2 weeks driving around with bushfire smoke lingering around.

    Coming home I noticed the DPF going through a regen cycle after only 130 to 150 kms. And it did this constantly all way home. The regen itself worked flawlessly with good temps. Vehicle drove as normal in every other way. But 7 regens to get home had me thinking there is an emission issue.
    Put the scantool on it to look at data with the MAF sensor in mind.
    What instantly pinged my interest was the intake air temp sitting on 38 deg, it was only 19 deg ambient temp. The grams/ per second was low but itself was functioning fine.
    3 times I had to clean MAF sensor to get the intake air temp reading back to what it should.

    Only thing I can put this down to is contamination from bushfire smoke.

    The other interesting thing is no fault code was logged, so not even the engine light come on. Nothing to even suggest there was an issue. Reason being the MAF sensor was still operating within its parameters.

    The only symptom was the DPF going twice as many regen cycles than I would expect it to.
    So if you have been driving around in bushfire smoke it would be a good idea to clean the MAF sensor.

    Cheers, Spook.

  • #2
    Originally posted by Spook1205 View Post
    Coming home I noticed the DPF going through a regen cycle after only 130 to 150 kms.
    Cheers, Spook.
    Interesting , mine has been doing that ever since the DPF replacement and ECU update in April this year. They did clean the 5th but maybe a MAF clean should be done at every 20k as well? I dont know if thats on the service schedule or it was done along with the DPF.
    I did suffer the dreaded limp mode after the Cape York trip , caused by dust ingress past the air filter. I did a MAF clean to get me going and the dealer cleaned out the intake tubing when i got back. I wonder now if the DPF issues start all the way back as a MAF issue? got to wonder eh ?

    2019 GX , in White


    • Spook1205
      Spook1205 commented
      Editing a comment
      From my understanding anything that will cause the air fuel ratio sensor in the exhaust not sensing what it should will cause the system to be extra cautious and that being the DPF will work overtime with any other adjustments the system can make within itself.

  • #3
    I think we have to start thinking DPF Delete solutions. I think in some states it’s legal. Mines a 2015, and no real probs so far, just had the expensive 4 year/80k service at Noosa Toyota. When Toyota start wiping their hands of any issues (5 year old cars), and the dpf needs replacing, maybe 10 years (maybe $4k??). I want to keep the car long term, and will find a good mechanic (not a Toyota dealer) to service too.


    • #4
      Frazza; I think blocking or deleting things like DPFs & EGRs is illegal everywhere due to pollution control regs. People do it, but its against the manufacturer's vehicle specs & if the engine plays up because of it, your insurance may be void leaving you an expensive bill... Others may know for sure.

      I've a 2015 I won't go back to Toyota unless for a recall. The lack of knowledge & fobbing off my issues $hits me. I get better info, tips & advice reading comments & asking questions on this Forum.


      • #5
        That's interesting Spook,

        I just returned from an 8100klm trip to Central Australia and found the distance between burns to vary quite a bit. On some occasions the DPF% grew very quickly and did its "reset" thing (e.g. jump from 80 to 40 then resumed climbing slowly) after only maybe 50ks which has been seen on occasion by others also. While it's not overly consistent, it still worked fine (no smoke, faults etc), and I'm at over 70K klms without issue now

        As I and others have found before, there are certain driving conditions which can cause burns to be very slow, e.g. towing at >100kph into a headwind. It could take an hour, all the while increasing fuel consumption by 2-3l/100k. I assume under such load there's just not enough spare oxygen reaching the DPF. In these cases I think its better to slow to 80-90 for a little while or pull over and do a manual burn. I think you'd use less fuel that way.

        The ambient temp varied a bit on my trip, but was regularly in the 38-41 zone, perhaps that helps explain the differences. I might add intake air temp to the scanguage (is it already a builtin?), and see how it differs from ambient, could be handy if its an indicator of a fault.

        Speaking of MAF cleaning, I was aware of the dusting issue (though haven't experienced it), so I was prepared and packed some MAF cleaner in the toolbox. Autobarn sell a small liquimolly brand can which is much more portable than the big 300g CRC cans.

        AFAIK, my car (2015 GX) has never had a 5th injector clean (I've never had a documented issue, so I doubt Toyota would have bothered). It's out of warrany now, and its definitely something I'd like to do. I'll have to dig up your video again, or even come and see you some time (I'm in Canberra, not far from the south coast).



        • Spook1205
          Spook1205 commented
          Editing a comment
          I’ll look for it then.
          Should be close to ambient temperature as it intake temps just after the air filter.

        • Spook1205
          Spook1205 commented
          Editing a comment
          Different diesel fuels from different fuel companies should not make any difference. But fuel with a higher cetane rating would be a choice if we actually had that choice.

        • dandin
          dandin commented
          Editing a comment
          Ambient Air, Intake Air and Charge Air Temps are all available to the ECU. I don't know how to get it onto your scan gauge but they're definitely there for logging/viewing.

      • #6
        Emailed Scan Gauge to ask if I can get Ambient Air, Intake Air and Charge Air Temps on my SGII. The reply I got was....

        The intake air temperature is build in gauge and can be found under iAT.

        For the other two please try to add via CANSF x-gauges that can be found here

        How to add the X-Gauges can be found in the user manual on page 39 or see the digital copy here

        Haven't tried it yet, sorry. But those of you more mechanically savvy, may make sense of this & can be of help.


        • #7
          Hi Fellas,
          I’m new to the forum so just getting the hang of finding information. I’ve been having regents occurring about every 100kms and sometimes more often. I just read your comments about intake air temp and did notice that mine seemed high given the ambient temp so found your info very helpful so a big thank you.


          • #8
            Originally posted by Lloydy View Post
            I’ve been having regents occurring about every 100kms and sometimes more often.
            I would be taking it in to Toyota to get sorted , every time you do a burn its 4 litres of diesel wasted , and at current prices of $2 per L its an even bigger waste

            2019 GX , in White