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  • F250 start rpm

    Hi, my 2015 Yamaha f250 seems to rev too high each time I start it.
    According to tach it will rev to2400-2700rpm and then drop down.
    Is this normal. Has done this since new. Thanks for any info.
    Ken

  • #2
    Normal. Nature of the beast. My Ford F150 truck also does the same thing.

    Does seem strange that when one reads about most engine wear occurring during a cold start that the motor would rev up during the start, but so be it. Maybe the thinking is that the higher the motor revs the faster that the oil will be flowing through the motor.

    Comment


    • #3
      Originally posted by boscoe99 View Post
      Maybe the thinking is that the higher the motor revs the faster that the oil will be flowing through the motor.
      Yes, but the number of revolutions that the engine turns without oil pressure will be the same.

      Comment


      • #4
        Maybe the wear is based on time and not revolutions. One might think revolutions but... Things are some times not what they seem.

        Wish I knew a Ford engineer that could tell me the rationale for the motor operating the way that it does.

        Comment


        • #5
          engine wear

          Wear is related to friction, lubrication is to lower friction but it also acts as an isolator between parts.

          So an engine would wear at a quicker rate when run faster. i.e. twice the speed is eight times the friction (cubed).

          However, at higher revs the oil pump puts out more pressure and therefore more oil per revolution.

          There is also the thing that an engine becomes more balanced when revved faster at no load. Sure more speed means more forces that, eg. piston its mass produces at the changes in direction would cause at it's little and big end; and this can be seen as more friction.

          This may be so, but at rotational surfaces (bearings) we will have centrifical forces throwing the surfaces away from each other. In the case of roller bearings the balls will be more suspended within their space.

          Remember this is true at no load. And at idle speed the engines output power is equal to what is required to overcome the engines internal friction!

          So the argument could be made that revving an out of gear engine some does reduce cold engine wear because of increased pump efficiency and self balance!!!

          Comment


          • #6
            Why do engines not have electic oil pumps?

            I might add that if one has an electric driven oil pump that operates for sometime before engine is rotated, all this concern about early (cold) wear would disappear!

            So why don't they appear anywhere? As consumers we should be louder.

            Comment


            • #7
              I believe Rodbolt has said in the past that the 300 or maybe it was the 350 will scare you when first fired up.
              EFI system have to adjust itself once it sees itself started and the ISC has to come back down from 100%

              Comment


              • #8
                Originally posted by 99yam40 View Post
                I believe Rodbolt has said in the past that the 300 or maybe it was the 350 will scare you when first fired up.
                EFI system have to adjust itself once it sees itself started and the ISC has to come back down from 100%
                Some of this may be true but the F250 and the F350 don't use an ISC. The electronic throttle valve opens and closes to get the correct idle air amount. But maybe it is the throttle valve itself that is having to seek the correct opening position.

                Now it makes me wonder why some Yams with an electronic throttle valve have an ISC and some don't.

                Comment


                • #9
                  Systems relying on feedback rather than prediction

                  Originally posted by boscoe99 View Post
                  Some of this may be true but the F250 and the F350 don't use an ISC. The electronic throttle valve opens and closes to get the correct idle air amount. But maybe it is the throttle valve itself that is having to seek the correct opening position.

                  Now it makes me wonder why some Yams with an electronic throttle valve have an ISC and some don't.
                  How things are managed in engines rely greatly on what is in "fashion" at the time. Advancement in engineering is no different than all the other things thrust upon us.

                  What controls what, in an engine, has moved around over the years.

                  The term "throttle" is still used to describe control of engine speed. And in fact it is the system still actually used today; that is we use a "valve" to reduce the amount of air entering an engine. If we didn't have this device inserted in the airway, engines would blast away at full power, a concerning thought given motors of today are extremely powerful and can destruct things in an extremely short space of time. I wait for the day that the engineering "fashion" addresses this from a point of view that air should be actually gradually added, just like fuel is (FI).

                  In practical terms the archaic throttle plate held back by a mere spring be replaced by something that is safer. (that humble spring that has been there over a hundred years, stands between you and disaster).(and oh can I mention a throttle plate sticking open).
                  Oh, they have half addressed the issue some, they now have "fly by wire" accelerator that now even eliminates your direct mechanical control the opening of this throttle.

                  It also used to be that ignition advance (a system to increase speed and engine power somewhat) was directly linked to the control lever for more power. It was also "fashion" at one time to link this with engine revolutions, and it was once linked to engine demand via vacuum which could only increase with speed; now it is determined by an electronic brain.

                  ISC as was traditional disappearing as fashion.

                  What is the future?, engine speed might be con*****ed remotely, by someone in another country through a government regulator, who is watching your every move.
                  Don't laugh, racing cars already are, manless drones are flown across the globe to replace conventional aerial warfare, they are testing driverless cars for you and I, some trains don't have drivers anymore......
                  Have you seen an airline pilot lately? They will have pilotless commercial planes soon.

                  After all, I see some comfort that airlines have "pioneered" fly by computer and it hasn't resulted in the doomsday predictions.

                  Comment


                  • #10
                    because the F250,some of the F225 and the big v6 motors use an electronic throttle assy similar to what the automotive world has used for the past 10-15 yrs.

                    the APS,or helm lever, sends an electronic signal(voltage) to the throttle shaft motor.

                    that is what moves the plate.

                    watch it sometimes when you turn the key OFF.
                    it moves to the WOT then back to the next start position.

                    the days of cables are numbered.

                    Comment


                    • #11
                      Has anyone heard of any of these fly by wire con*****ed outboard motors having runaways like the Toyota's cars in the past?

                      Kind of scary even my 2014 Ford F150 does not have a throttle cable ,guess they all are heading that way

                      Comment


                      • #12
                        never heard of a runaway on the Volvo,mercruiser or Yamaha.

                        Comment


                        • #13
                          Just a matter of time before a "hacker" does it. At least on the boat you'll have some distance away from a potential hacker..



                          Their hacking cars electronics etc right now..
                          Scott
                          1997 Angler 204, Center Console powered by a 2006 Yamaha F150TXR

                          Comment


                          • #14
                            Originally posted by 99yam40 View Post
                            having runaways like the Toyota's cars in the past?
                            you do know that was all hysterical b.s. ?

                            ...the Department of  Transportation released the results of its study into the blizzard of reports that various Toyota and Lexus models were accelerating out of control. The DOT concluded that, other than a number of incidents caused by accelerators hanging up on incorrectly fitted floor mats, the accidents were caused by drivers depressing their accelerators when they intended to apply their brakes. “Pedal misapplication” was the DOT’s delicate terminology  for this phenomenon.

                            It's All Your Fault: The DOT Renders Its Verdict on Toyota's Unintended-Acceleration Scare – Feature – Car and Driver

                            Comment


                            • #15
                              to hack into the system requires a wireless connection such as onstar or whatever ford and chysler calls their stuff.
                              I know my wifes car can get wireless updates. it would be possible to access the ECU I guess.
                              so far boats don't have that,at least not small boats.
                              cant remember on the Yamaha and merc but on the Volvo if the HCU losses communication with the PCU it shuts the engine down.
                              I am still not so sure of the helm master or the EVC Volvo stuff and salt water.

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