Mpg calculator

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  • Trindaddy
    Senior Member
    • Jan 2010
    • 339

    Mpg calculator

    Hi guys. I wondered if i could run something by you. I am having a disagreement with a tech on IATN about the effects of tire/rim size on on-board mpg calculators. I am comfortable being wrong with you guys and sometimes the boys on IATN can be cantankerous. Anyhow, i think tire diameter can skew the on-board average fuel economy readings, he feels it may create speedo error but not effect calculations. I understand the vehicle can likely create instant mpg without the distance input but wont the wrong size tires create an actual average mpg that is different than what the car's fuel calculator thinks it is. What say you guys? Neil
    Last edited by Trindaddy; 05-30-2011, 08:34 PM. Reason: Found better adjective
  • hefaus
    Senior Member
    • Dec 2007
    • 435

    #2
    mpg cal

    I am with you. 16inch tire 20 inch tire. measure distance on tire valve stem 1 revolution. Measure distance, repeat with 20 inch tires.Which one will cover more distance? Seems it should throw out milage as well as speed. Hope this helps your side. Keep Smiling.

    Comment

    • scottgroen
      SDE Member
      • Nov 2006
      • 14

      #3
      You really think I don't get around much, huh?

      Comment

      • Joe Rappa
        Snap-on DSD
        • Aug 2007
        • 2050

        #4
        I agree with you. If the speedo is off, the fuel mileage calculation has to be off by the same amount.

        Joe
        "You don't build a reputation on what you're going to do"
        Henry Ford

        Comment

        • Crusty
          Senior Member
          • Dec 2007
          • 2450

          #5
          Originally posted by Trindaddy
          Hi guys. I wondered if i could run something by you. I am having a disagreement with a tech on IATN about the effects of tire/rim size on on-board mpg calculators. I am comfortable being wrong with you guys and sometimes the boys on IATN can be cantankerous. Anyhow, i think tire diameter can skew the on-board average fuel economy readings, he feels it may create speedo error but not effect calculations. I understand the vehicle can likely create instant mpg without the distance input but wont the wrong size tires create an actual average mpg that is different than what the car's fuel calculator thinks it is. What say you guys? Neil
          You're right Niel. It will also affect transmission shifts and engine loads too. How can that not affect MPG calculations? The algorythyms are a complex interractive compilation of inputs and resulting outputs.
          What's that old saying?....Garbage IN, Garbage OUT?....LOL
          It's amazing how much one scewed input can affect a miriad of other outputs. This is why code fault repairs are easy compared to vehicles that react strangely to a confused sensor, which is out of calibration, yet just inside the failure parameter limits, yet doesn't set a code.
          That's another BASIC reason why I am so anal about seeing ALL the pids the manufacturer puts out on the datastream which is available at the ALDL.

          Comment

          • sbreland73
            Senior Member
            • Jan 2009
            • 1076

            #6
            Originally posted by Trindaddy
            he feels it may create speedo error but not effect calculations.
            How DOES one come to that conclusion? Is speed NOT in a relationship to distance? If a measuring device is performing calculations, and one input is distance, which is derived from a speed sensor, then HOW can speed be affected, and not distance? Perhaps if the device were using satellites in a GPS setup, then I would side that wheel size have no bearing on a reading. On that note, that would be a sure way to test. Reset the trip odometer to zero, and observe the distance of say 30 miles, compared to a GPS device in same vehicle. Modern GPS mechanisms have become very accurate.
            S. Breland

            Comment

            • Trindaddy
              Senior Member
              • Jan 2010
              • 339

              #7
              Originally posted by scottgroen
              You really think I don't get around much, huh?
              Well, i dont recall seeing you here. These guys usually don't have a problem admitting when they may be wrong. Doesn't seem like your kinda crowd Scott.

              Are you ready to conceed yet?

              Respectfully,
              Neil

              Comment

              • Matt_Ragsdale
                Member
                • Jul 2008
                • 46

                #8
                You are correct that tire size can and will affect onboard and offboard (if you are using odometer values) miles per gallon calculations.

                You are wrong that folks on iATN can't admit when they are wrong. It is a great forum with still a few good people left.

                I wouldn't start a forum war...especially from here. It's not very professional.

                Take care,

                Rags

                Comment

                • Trindaddy
                  Senior Member
                  • Jan 2010
                  • 339

                  #9
                  What is not very professional is openly belittling someone who is offering his opinion, wrong or right, ("I like guys like you, ya'll make me money"), finding out you are wrong, then not being man enough to clear the air. I did what i did to make sure i was right and i dont need to justify that with you or anyone else! I respect you and your obvious vast experience, but i wont stand for someone making me out to be a fool. I pay for IATN like everyone else and I, like everyone else, deserve to be treated with respect. At least on this site that doesn't appear to be a problem. Thats my opinion, and I'm entitled to it! If you dont like it, thats tough. I will choose to either contribute to IATN forums or not, but sadly i have to say, comments like the ones you often make and the one that Scott made are becoming a deterrent for honest guys like me. I may not be the genius some of you are but at least i got the decency to know the power of the words "I'm sorry i was wrong". Just how i was raised, like it or not.

                  Friends, Have a hybrid customer that found me on the web. His complaint was a continual drop in fuel economy, all the way down to 37mpg. His MIL was on but the only code was a P0420. He was concerned his battery was failing because the vehicle lacked power o...


                  Neil
                  Last edited by Trindaddy; 05-31-2011, 05:50 PM. Reason: Added link to IATN forum

                  Comment

                  • Matt_Ragsdale
                    Member
                    • Jul 2008
                    • 46

                    #10
                    I am not defending Scott. He is not the one who emailed me asking for my input to get in the middle of the argument you two were having. You are. That is the only reason I even took the time to read the exchange between the two of you. You emailed me and asked me to.

                    So I did. And I responded. I gave you a response and it was factual. You later on said I didn't have the balls to post it there and post it here. Look again. It was posted 11 hours ago on the other site and later on this site when I read your tirade bashing a whole network of people....all because Scott made you angry.

                    I have not belittled you. I only gave you what you asked for. My input. And this is the treatment I now get from you.

                    Your thread here is unprofessional, your tirade above is unprofessional, and your response to me on iATN was unprofessional. Especially considering the time and effort I took to give you what you asked for.

                    I don't know what else to say.

                    Rags

                    Comment

                    • Trindaddy
                      Senior Member
                      • Jan 2010
                      • 339

                      #11
                      Fortunately Matt, you are not the only one that gets to decide what is "unprofessional":

                      Letting your fellow IATN critic belittle a contributor who is trying to help is unprofessional.
                      Standing by when you could help someone in need is unprofessional.
                      Plainly stating on one site that i'm right then going on another and saying the opposite is unprofessional.
                      Turning this around to read that i am 'bashing an entire network of people" is rediculous and unprofessional.
                      Preaching to me, another IATN sponser, about what YOU think is unprofessional, is unprofessional.
                      Marginalizing the whole reason i did all this is because YOU think i'm mad at Scott is a joke, and unprofessional.
                      Telling everyone that you "didn't notice Scott and i were having this problem" when you were posting on the same thread is ludricrous and ...unprofessional.
                      Acting like i'm enjoying this when i've tried so hard to "harden my skin" with you guys and be part of the IATN forums is unprofessional.
                      Constantly casting judgement and snide remarks to MANY people on IATN, then criticizing me for standing my ground is unprofessional.

                      Say whatever you want Matt, never stopped you before.

                      I regret having to display this to my peers on this site. It is not my nature and i am NOT enjoying this, I've simply had enough. I've posted the threads. Please read them and you will see I politely and professionally tried to help someone and got trashed for it because of insulting remarks, big egos and the inability to say "i'm wrong".

                      Neil

                      Comment

                      • sbreland73
                        Senior Member
                        • Jan 2009
                        • 1076

                        #12
                        WOW, I have heard stories of this sort taking place on that site. I have also been told that there is not the "confirmation" of a "fix" over there like there is on Identifix. I am not a member of iatn, so I don't know, just what I've been told, but it has been described to me as a forum, where Techs say what they want, and if you don't know better, you could be misled. This thread would seem to confirm such statements. I hope you all can work it out.
                        S. Breland

                        Comment

                        • scottgroen
                          SDE Member
                          • Nov 2006
                          • 14

                          #13
                          Originally posted by Trindaddy
                          I pay for IATN like everyone else and I, like everyone else, deserve to be treated with respect.

                          Neil
                          THIS is a very popular misconception you young guys seem to have- RESPECT is earned, not purchased. I know it would be easier that way, but life sucks.

                          Comment

                          • Matt_Ragsdale
                            Member
                            • Jul 2008
                            • 46

                            #14
                            Look. You sent me an email that asked me to look at the exchange between Scott and you. I did that. So I addressed the original post where Scott responded to you. I gave you my input like you asked.

                            I don't know what else you want from me. You told me you did not want me to take sides, and I did not. I just did as you asked. Nothing more.

                            Yet that is not enough. You are acting like a child who is arguing with another child and playing the he said she said game.

                            I think you really need to step back, take a few deep breaths and realize that the argument with Scott is not that important.

                            For anyone that wants to read that what I say here is a fact, here is the link to the post I put up right after I read his email asking me for my input:


                            [...trimmed text...]I'd say you are probably wrong. Even if the MAF really was underreporting airflow and cleaning it fixed it, it likely didn't cause low fuel economy figures on the display.


                            So even though I was asked for my input and I gave it, and asked not to take sides and didn't, he comes out throwing stones at me and iATN claiming that nobody stood up for him to give him ammo he was right. He is a liar. I told him he was right, but that's not good enough. Even though he asked me not to take sides he wanted me or someone else to chastise Scott, even though I am not sure others are really clear what the childish little argument was about.

                            Good lord.

                            Rags

                            Comment

                            • Matt_Ragsdale
                              Member
                              • Jul 2008
                              • 46

                              #15
                              Originally posted by sbreland73
                              WOW, I have heard stories of this sort taking place on that site. I have also been told that there is not the "confirmation" of a "fix" over there like there is on Identifix. I am not a member of iatn, so I don't know, just what I've been told, but it has been described to me as a forum, where Techs say what they want, and if you don't know better, you could be misled. This thread would seem to confirm such statements. I hope you all can work it out.
                              iATN is far better than Identifix and better than the forums here for certain things.

                              He had a disagreement with a guy over there, and I am not even sure the two were arguing about the same thing. Most times folks don't even bother reading an argument between two people, especially when they BOTH end up being a bit childish. Stepping in the middle just gets mud on you, as Neil has shown here. Against my better judgment I stepped in and did as he asked, and look what it got me. Now I have just as much mud on me as those two...and all I did was offer help. It's been my experience that any forum can be that way.

                              Some folks just need thicker skin, I suppose. I am often left wondering if they dwell on things in their real lives as much as they do things on the internet. If they do, I wonder how they function. One certainly can't be a successful technician without thick skin...you get chewed up and spit out rather quickly.

                              Rags

                              Comment

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