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running out of get up and go.

Discussion in 'Range Rover' started by tomcat59alan, Apr 15, 2019.

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  1. Datatek

    Datatek Well-Known Member

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    I ran for some time with the MAF unplugged as an experiment. As you have found, a little more fuel is used and the car would smoke under hard accelaration.
     
  2. Datatek

    Datatek Well-Known Member

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    Very hard not to understand, it's written in words of one syllable.
    You also confirmed in a post a week or so ago that a duff MAF causes loss of power because as you put it the ECU goes crazy. It's not down to EGR miss operation because it does it with the EGR disabled.
     
  3. wammers

    wammers STILL BREATHING. Donater

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    Yes it does when the ECU does not receive expected signals it can cause it to lose the plot. Allow me to inform you that one of the descriptions of what the MAF does on the diesel in RAVE can be interpreted as how a MAF works on a petrol engine. It does not relate to a diesel in any way. I know that obviously you don't. The airflow through the MAF sensor on a diesel apart from it's temperature as explained earlier has no effect on fuelling in any way.
     
    Last edited: May 21, 2019
  4. Datatek

    Datatek Well-Known Member

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    I might believe that if disconnecting the MAF did not cause an increase in fuel consumption.
    RAVE is quite clear:-
    IMG_0854.jpg
    I might also believe that RAVE is wrong if I had not done tests that prove it's correct.
     
  5. wammers

    wammers STILL BREATHING. Donater

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    Keith you are talking nonsense. Airflow through the MAF has nothing to do with injection fuel quantity. Fuel injected is subject to power/RPM request. The higher the throttle request the more fuel is injected to achieve that request.. The more fuel that goes in the faster the engine turns. Air in the cylinder for any given manifold pressure RPM is constant. There is ALWAYS more air in the cylinder than is needed for combustion. Fuel is NOT injected subject to airflow through the MAF sensor. You don't know what you are talking about. You CANNOT fuel a diesel engine subject to airflow through the MAF sensor it is not possible, because diesel engines DO NOT run at a set mixture ratio as do petrol engines. At idle the air/fuel mixture ratio will be well over 100 to 1.
     
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  6. Datatek

    Datatek Well-Known Member

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    I suspect that your garage closed before electronic control of diesel fuel injection arrived, all modern diesels use a MAF to adjust fuelling to compensate, for among other things, atmospheric pressure. The higher the throttle request the more fuel is is injected but there never was a direct relationship even in mechanical as the governor related the fuel injected to the RPM, the finer that control can be made, the less smoke will be produced due to over fuelling.
    Unfortunately in the case of the M51 it's a bit crude but test results often disprove theories, if the MAF has no effect, why would fuel consumption increase with the MAF unplugged even with the EGR disabled?.
    Anyway I'm flogging a dead horse, you believe what you want to believe, I believe what I find out from testing.
     
  7. wammers

    wammers STILL BREATHING. Donater

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    As explained earlier if you bothered to read it. The ECU uses the temperature of the air in conjunction with fuel temp to determine air density, fuel density. The amount of fuel to be injected to suit throttle demand is then adjusted minutely by the ECU to suit conditions. The fuel injected is determined by the throttle power request NOT by the amount of air passing through the MAF sensor. In pre EGR engines air temp was measured in the manifold after the turbo. When EGR was introduced that sensor was deleted and it's parameter in the ECU became a fixed -38.88 value. The temp reading from the MAF sensor is used as a substitute for that sensor. So the only thing the ECU actually needs from the MAF unless EGR is active is the temp reading. Air flow is of no consequence to the ECU unless EGR is active, in which case the reduction in airflow represents the amount of exhaust gas being ingested. The ECU will then modulate the EGR valve to ensure sufficient oxygenated air is present for clean combustion at the requested throttle power demand. IF the temp reading from the MAF is not available, the ECU uses a substitute value based on a preset value and fuel temp only. If you read through RAVE it is all in there, albeit in some cases a little vague and open to misinterpretation by those with no knowledge of diesel mechanics. Like you and a few others on here basically.
     
    Last edited: May 22, 2019
  8. Grrrrrr

    Grrrrrr Jedwood Spannerhands

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    I suspect I am not alone in having only a rudimentary knowledge of how an old diesel engine works, let alone one of the newer ones. I'd even go as far as saying I am in the majority.

    Learning a little here though. Through discourse we learn ... and fiddling with the beast, of course.
     
  9. wammers

    wammers STILL BREATHING. Donater

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    New diesel engines work in exactly the same way as old diesel engines.
     
  10. Henry_b

    Henry_b Well-Known Member

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    I can feel a duel coming on, between Data and Wammers.........

    handbags at Dawn :p:D
     
  11. Dippypud

    Dippypud Never Knowingly Understood

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    Worth while setting up a popcorn stand ?
     
  12. Henry_b

    Henry_b Well-Known Member

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    Yep Dips, but my Popcorn stand is high and dry at the moment :(

    I fink you'll have to have a truckload delivered :cool::D
     
  13. Dippypud

    Dippypud Never Knowingly Understood

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    Do we know any delivery drivers ? ;)
     
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  14. Henry_b

    Henry_b Well-Known Member

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    Hmm there are a few ;)
     
  15. wammers

    wammers STILL BREATHING. Donater

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    No need he is wrong period. It is for people to listen and learn or remain ignorant. Bit like the dickhead in one thread who reverse engineered (his words) ECU outputs. He seriously thought that a certain airflow through the MAF represented a certain injected fuel quantity. In other words fuel was injected to match the airflow. When in fact it is the other way around. The more fuel the faster the engine turns, the faster the engine turns the more airflow. Bloody idiot.
     
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  16. Datatek

    Datatek Well-Known Member

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    Even though they have butterfly valves in the inlet manifold to restrict airflow?
     
  17. Mark Piercy

    Mark Piercy Well-Known Member

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    Ok guys, let's leave that one to sleep it out. Please:p..



    F├╣cking running away and fast.....










    See me go.......






    Not quite.......




    Yet.....










    ....
    .


    .
     
  18. wammers

    wammers STILL BREATHING. Donater

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    Oh dear you really don't have a clue do you.
     
  19. Mark Piercy

    Mark Piercy Well-Known Member

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    So.....
    What about the weather today hey?
    thinking-face_1f914.png
     
  20. Henry_b

    Henry_b Well-Known Member

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    Rather sunny here.. ;)
     
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