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  • acceleration problem

    This problem usually only occurs when the vehicle is first started. It can occur when the engine is hot or cold, I had it happen once when after driving 150 K, I stopped for 10 mins, got back into the vehicle and pulled out onto the highway in an 80K zone and the vehicle refused to accelerate even though my foot was to the floor for about 3-4 seconds, causing a rapidly approaching semi to stand on his horn, after the delay the vehicle accelerated away normally with no misses or anything.
    The usual occurrence of the problem is after I have parked the vehicle for about 2 hours and then it will on occasionally refuse to accelerate for up to about 5 seconds even though by this time my foot is to the floor.
    On one occasion whilst driving I was stopped at a roundabout for about 30 seconds, then when I entered the roundabout the problem occurred much to the annoyance of other drivers.
    I don't get the problem when I leave home, I think because I have a long narrow driveway and by the time I have reversed out, it is enough time for the problem to go away.
    The vehicle is a 2017 GXL auto Fortuner with the 2.8 diesel which has done 30000 K, The problem has basically been there since new, and in the 2 years has occurred at least 50 times. The dealer has run the normal diagnostic tests but nothing shows up. They initially said I had my foot on the brake, and/or the floor mat was causing it, I think they now believe me, but have no idea as to the cause of the problem.
    I have attempted to demonstrate the problem to the dealer by leaving the vehicle parked there for 2 hours or so, but of course it won't do it when you want it to. I asked the dealer would it be possible to connect a data logger to the vehicle for an extended period of time to capture the problem when it occurs, They said they only had a scan tool which would only record for 1 hour.
    The issue is you cannot predict when ti will occur, for example the other day I drove home and parked on the street, after about 2 hours I went out drove about 5 K's parked for about 2 hours and when I went to go home the problem occurred.
    Any thoughts or questions?

    Cheers
    Bruce

  • #2
    The accelerator pedal I just a request for power. 2 main things to give power are fuel and boost.
    firstly I would look at accelerator pedal request, this would give a DTC as it has 2 signals that cross check each other. It’s an easy check with live data on scantool.
    secondly would look at the boost side of things. The variable vane position is easy to check with live data. After that would check the PWM signal that operates the variable vane on turbo.
    these are just my thoughts on what process I would go down for this symptom.

    Comment


    • #3
      sounds like a dangerous fault mate , i would call Toyota head office and ask for one of their more experienced engineers to look at it. Regardless of trouble codes you would think that they would at least try swapping the pedal unit or the turbo VNT unit with another one to narrow down the problem.

      Engine control , ECT , AT , cruise control and connectors.pdf Ive attached the wiring diagram so you can see how it all connects together.
      2016 GX , in White

      Comment


      • #4
        I know this doesn't help you, but I had a similar problem with my auto GU Patrol. During a Simpson Desert crossing & for no apparent reason she started blowing smoke & wouldn't accelerate. Best guess at the time was the air-fuel mixture & thought the mass air flow sensor was the problem.

        I'd turn off the engine & restart but no good. I'd crawl for a bit then slowly speed up to 100kph. The Birdsville mechanic couldn't clear the fault codes. Went to the nearest town with a Nissan dealer who cleared the codes & good as new. Different cars & technology, but with the exception of blowing smoke, sounds like a similar problem to you with acceleration. Unfortunately nobody could tell me why or what caused it to happen.

        Comment


        • #5
          Thanks for your replies.

          Spook1205, Are you saying that the testing you are suggesting would possibly show a problem when the vehicle is running normally? Shouldn't the dealer be doing this with their scan tool? or am I expecting too much?

          White One, I had been thinking of trying to escalate the problem with Toyota Australia, You have spurred me on to do that. I agree with your suggestion that the dealer should try swapping out likely parts, I think they have been blaming me for the problem, and are only now thinking there may actually be a problem. Probably somewhat my fault as I haven't pressed the issue enough, mainly because it is normally just an annoyance, but after the instance with the semi trailer I am anxious to have the problem resolved. Thanks for the wiring diagrams, unfortunately I got lost on the first page, what happened to linkages and cables!!

          Anthony, Sounds similar in some ways, but my problems only lasts for a few seconds maybe up to 5 seconds, and then every thing is good until it occurs next time which may not be until several weeks. The dealer says there are no error codes being recorded, I guess I have to trust them.

          Thanks Guys
          Bruce

          Comment


          • Spook1205
            Spook1205 commented
            Editing a comment
            Depending on the knowledge of the tech will depend on the diagnostic process. They can all scan for diagnostic trouble codes, but a DTC’s will only trigger if something goes outside it’s working parameters.
            Realistically you need to watch relevant live data which I mentioned whilst it does the fault. Or data log the data and then look at that after it happens. The tech will need to understand the PID data and what and how they interact. It not that hard though.

        • #6
          Hi Spook1205;
          The difficulty with the problem is that it may not occur for several weeks, which is why I suggested to the dealer that could they capture the data from the system over an extended period, but they said they could not. Are you aware of any way I could connect up a laptop or similar to record the data (or maybe a memory stick?), even it it just looped after a period of time as I could disconnect it once the problem happened.
          Maybe I am just over simplifying the recording of the data.

          Cheers
          Bruce

          Comment


          • #7
            https://www.afiaustralia.com.au/test...r-obd-recorder
            something like the above works in a 24 hour loop.
            there would be a large range of quality and price logger available. Most workshops would not be equipped with one unless they did a lot of intermittent faults such as yours.
            if you got one I would be happy to look at the data for you.

            Comment


            • #8
              intermittent faults are the hardest to find , but i know they have engineers who can do all sorts of things to look for the problem. At the end of the day there is nothing a driver can actually do to cause that problem so let the engineers have a look. Its thier product , they have loads of information and an escalation process in place , and you never know they may have come across this issue with another customer and go direct to the fix, whereas the dealer may not.
              many many moons ago in a past life i was operations manager for a bus company in western Sydney. We bought a bunch of new Volvo B7RLE buses in 2003 which used to do exactly what you described. A restart used to fix it so it didnt cause too many major headaches. The selling dealer refused to look at the issue , blaming the drivers , blaming the fuellers , blaming everything else besides the bus. Till one day the bus broke down doing a turn across the Gt Western Highway and would not reset. The traffic was a nighmare and made the evening news . Our chief mechanic went public with the issue and the lack of action from Volvo ,( with my full support ,and threats of buying Merc buses ) and the next day they sent an ****nal of engineers to look for the problem , which ended up being the main ECU. moral of the story is dont give up. VW only now are being forced to recall the DSG equipped cars which failed into neutral due to a known issue. took about 3 deaths before the scumbags acted !!
              2016 GX , in White

              Comment


              • #9
                I'm surprised data logging isn't a standard feature nowadays considering the amount of software a late model car comes with onboard.

                Like Spook has said, OBD loggers are available out there. You have to know how to configure it to use for a specific vehicle, I don't expect you'll come across a plug and play model.

                ​​​Good luck and don't give up harrassing your dealer. The culprit will likely be an electronic part because your issue is intermittent. If you know anyone with a Hilux or Fortuner I'd try swapping parts over like the AFM/MAF, the throttle pedal sensor and the electronic throttle motor.

                Comment


                • #10
                  Logged data is most commonly freeze frame data, which is relevant data attached to a diagnostic trouble code. It’s data before and after the DTC is triggered.
                  thinking about this logically (these are just my thought processes) any actuator like turbo, throttle motor, EGR ect all have a position sensor, so if it was just stuck the expected value would be too far outside the actual value. These are all measured in a voltage range from .5 volt up to 4.5 volt or somewhere in between.
                  So we can initially rule a stuck component out. But looking at turbo vane position or fuel rail pressure compared to accelerator position sensor can give us an idea if the ECU has actually taken measures to deliver more power once the request has been given / received. Any break in accelerator pedal power, earth and both signals will log a code as the either signal voltage will go outside expected range when ignition is on / vehicle running.
                  if the signal to give more power is then not acted upon, you would start to go down the ECU faulty route.
                  if the ECU is sending out signals to change turbo vane position, rail pressure, close EGR, injection timing and injection fuel quantity then you would compare that to Mass air flow (MAF) as it should increase. Which it isn’t as the engine is not increasing in RPM.
                  out of all these situations if not an ECU issue I would go to the fuel metering valve (controls fuel rail pressure) as the most likely culprit and which may not log a fault code as it has no position sensor.
                  ill think more about this can of worms.
                  again thoughts only as diagnosing over the interweb without seeing car is just impossible to varify the cause of the fault.

                  Comment


                  • #11
                    Freeze frame data, like you said will only trigger if a sensor outside the know working parameters. There are loggers that will log everything (or everything you only want it to log). I have one in my other car.

                    Thinking about what Spook typed, leads me to believe it's the TPS (throttle pedal/position sensor). Generally it's a 0-5v sensor and 0-0.5v is considered off throttle and 4.8-5v is 100% throttle. I've had throttle sensors go in the past (in other cars, Nissan and Mitsubishi) and that was before OBD logging was a thing. It wasn't until I had aftermarket ECUs installed that the problem was apparent.

                    Edit: Just re-read what I typed in my previous post, our cars don't have an butterfly valve in the throttle being a diesel (my bad, I'm normally dealing with issues in gasoline/E85 powered cars)

                    Comment


                    • Spook1205
                      Spook1205 commented
                      Editing a comment
                      You are correct in saying there is butterfly throttle, just is used to mainly help with EGR mixing and smooth shutdown. It’s how we can get a slight manifold vacuum in the engine. This is something we discussed a long time ago that I was completely wrong about because the parameters on my scangauge where not set up as needed and at that stage had not put an actual scantool on vehicle.

                  • #12
                    I have borrowed an accelerator pedal from a 2017 Hilux from a friend who has a wrecking business and fitted it yesterday (easy only 2 bolts and the connection) seems like it is the same, now waiting to see if problem still occurs. I also reported the problem to Toyota Australia by email over the weekend with the same text I raised the problem with on this forum and received a phone call also yesterday to discuss the issue, was told that they would investigate further, contact the dealer and get back to me, so waiting to see what happens there as well.

                    Comment


                    • Spook1205
                      Spook1205 commented
                      Editing a comment
                      If a pedal sensor has any malfunction it will log a fault code. Reason being the 2 signals sent to the ECU would go out of range if power, earth or signal was disrupted. There is two signals running off different voltage ranges that the ECU monitors, the two are used so the fault code will trigger if one goes out of whack.
                      Honestly I don’t think the pedal sensor will fix it, but in saying that it’s worth trying and sometimes things are so left field it doesn’t make logical sense.

                  • #13
                    Agree with your thoughts Spook but it is very easy for me to try as I had access to another pedal assembly.

                    Comment


                    • Spook1205
                      Spook1205 commented
                      Editing a comment
                      100% worth a go as it’s not like it has cost you anything.

                    • Spook1205
                      Spook1205 commented
                      Editing a comment
                      Would like to get hold of your car for a look if you can get a couple of hours south of Sydney.

                  • #14
                    is there any possibility of a mechanical issue of some kind between the pedal arm itself and the internals of the pedal sensor? My Yamaha XTX had that issue when new in 2005 , the sensor was being operated by the throttle cable but the wipers inside the sensor did not register any voltage change. all affected bikes were recalled to replace the throttle sensor.
                    2016 GX , in White

                    Comment


                    • Spook1205
                      Spook1205 commented
                      Editing a comment
                      Anything is possible but being so interment and it’s a delay not a no go at all seems unlikely.

                  • #15
                    Hi Spook, I am in Newcastle, how far south of Sydney are you? I am thinking of looking at a tractor around Bowral in the next few days so maybe possible.
                    Cheers
                    Bruce

                    Comment


                    • Spook1205
                      Spook1205 commented
                      Editing a comment
                      In Kiama. About 40 min from Bowral.
                      I am camping this weekend but home Sunday afternoon and anytime Monday or through the week would be ok. Work is flexible.
                      Send me a message if that suits.
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