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MegaSquirt and Ignition rev limiters.

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  • MegaSquirt and Ignition rev limiters.

    How does Megasquirt (particularly MS2) respond to MSD (or any other make) rev limiters? What kind of behavior would I expect if the limiter is set at 3000rpm and the pedal is mashed to the floor? As long as the appropriate VE box is set right all is well? Does it not like being limited that way? Or it simply doesn't care, the rpm's are what ever the rpms are? Just wondering.
    Escaped on a technicality.

  • #2

    Re: MegaSquirt and Ignition rev limiters.

    Re: MegaSquirt and Ignition rev limiters.

    It shouldn't have any effect if it's wired up correctly.

    Comment


    • #3

      Re: MegaSquirt and Ignition rev limiters.

      Re: MegaSquirt and Ignition rev limiters.

      Thanks Matt.
      Escaped on a technicality.

      Comment


      • #4

        Re: MegaSquirt and Ignition rev limiters.

        Re: MegaSquirt and Ignition rev limiters.

        I just remembered one potential issue - don't have anything that can change the VE table based on O2 feedback, like AutoTune or Automatic Mixture Control, active when you hit the rev limiter. Other than that, the best way to look at it is if you have it wired up in a way where the car's tach works, the MS will work too.

        Comment


        • #5

          Re: MegaSquirt and Ignition rev limiters.

          Re: MegaSquirt and Ignition rev limiters.

          Thanks again Matt.
          Escaped on a technicality.

          Comment


          • #6

            Re: MegaSquirt and Ignition rev limiters.

            Re: MegaSquirt and Ignition rev limiters.

            are you running an MSD box? if so, I'd disable it's rev limiting function and use just the MS for this. It has a better algorithm for spark cut...

            or are you having issues with a pseudo rev limiter? it happens! lots lately. lol
            www.realtuners.com - catch the RealTuners Radio Podcast on Youtube, Facebook, iTunes, and anywhere else podcasts are distributed!

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            • #7

              Re: MegaSquirt and Ignition rev limiters.

              Re: MegaSquirt and Ignition rev limiters.

              I haven't decided if I'm going to keep it on the car or not once I have the MS2 controlling spark. The thing of it is that the MSD box I have has the 2-step limiter, so way down the road I could hook the limiter up to the clutch pedal switch and when at the line lay the gas to the floor with the clutch in and let the lower limiter hold the rpm until I release the clutch. Just thinking right now. Odds are the MSD box might end up on the T-bird to give a good tach signal to the MS1 (though the one it was getting wasn't bad when it was working...).
              Escaped on a technicality.

              Comment


              • #8

                Re: MegaSquirt and Ignition rev limiters.

                Re: MegaSquirt and Ignition rev limiters.

                I haven't decided if I'm going to keep it on the car or not once I have the MS2 controlling spark. The thing of it is that the MSD box I have has the 2-step limiter, so way down the road I could hook the limiter up to the clutch pedal switch and when at the line lay the gas to the floor with the clutch in and let the lower limiter hold the rpm until I release the clutch. Just thinking right now. Odds are the MSD box might end up on the T-bird to give a good tach signal to the MS1 (though the one it was getting wasn't bad when it was working...).
                MS2e has a launch rev limiter, doesn't it???

                Although I like the MSD boxes on an application like yours, it's nice to have a hot CDI spark on a distributor where charge time is limited... and the multi-spark discharge does a good job making up for the short duration of that spark at low RPMs.
                www.realtuners.com - catch the RealTuners Radio Podcast on Youtube, Facebook, iTunes, and anywhere else podcasts are distributed!

                Comment


                • #9

                  Re: MegaSquirt and Ignition rev limiters.

                  Re: MegaSquirt and Ignition rev limiters.

                  Take care to shield the two from each other, they don't always play nice. We had to remove the DIS 2 from our car in order to remove some electronic noise.

                  Comment


                  • #10

                    Re: MegaSquirt and Ignition rev limiters.

                    Re: MegaSquirt and Ignition rev limiters.

                    If your on a run, and have spray hooked up, it goes into the over rev limiter it will lift the head, because it does not kill the spray just the fuel or ign. :'( This I know, even if its noise making it think its in over rev. at a lower rpm
                    2007 SBN/A Drag Week Winner & First only SBN/A Car in the 9's Till 2012
                    First to run in the .90s .80s and .70's in SBN/A
                    2012 SSBN/A Drag Week Winner First in the 9.60's/ 9.67 @ 139 1.42 60'
                    2013 SSBN/A Drag Week, Lets quit sand bagging, and let it rip!

                    Comment


                    • #11

                      Re: MegaSquirt and Ignition rev limiters.

                      Re: MegaSquirt and Ignition rev limiters.

                      If your on a run, and have spray hooked up, it goes into the over rev limiter it will lift the head, because it does not kill the spray just the fuel or ign. :'( This I know, even if its noise making it think its in over rev. at a lower rpm
                      correction, if you have a "noise" problem - ours was a loose ground for the ignition - you might lift a head because you are launching spark events way out of time.

                      If you are spraying and hit any kind of rev limiter, or go out of your set RPM window, the nitrous and extra fuel are shut off.

                      -Scott
                      www.realtuners.com - catch the RealTuners Radio Podcast on Youtube, Facebook, iTunes, and anywhere else podcasts are distributed!

                      Comment


                      • #12

                        Re: MegaSquirt and Ignition rev limiters.

                        Re: MegaSquirt and Ignition rev limiters.

                        on this we disagree, the two step kicks in and the intake is still full of spray (your not shutting it off) just not used, shuts the fuel off at the runner but this allows even more volume of spray to enter from the plenum then the fuel turns on and spark, boom
                        2007 SBN/A Drag Week Winner & First only SBN/A Car in the 9's Till 2012
                        First to run in the .90s .80s and .70's in SBN/A
                        2012 SSBN/A Drag Week Winner First in the 9.60's/ 9.67 @ 139 1.42 60'
                        2013 SSBN/A Drag Week, Lets quit sand bagging, and let it rip!

                        Comment


                        • #13

                          Re: MegaSquirt and Ignition rev limiters.

                          Re: MegaSquirt and Ignition rev limiters.

                          on this we disagree, the two step kicks in and the intake is still full of spray (your not shutting it off) just not used, shuts the fuel off at the runner but this allows even more volume of spray to enter from the plenum then the fuel turns on and spark, boom
                          nope, there's a taper shutoff for the fuel specifically for that purpose. It doens't chop the nitrous fuel so it avoids a lean spike, emptying the intake manifold of nitrous...

                          Your issue had *zero* to do with any kind of rev limiter. You had spark events happening randomly - 80 BTDC, etc. that's what lifted a head. There's no issue with the logic in the software or hardware, at all , as it's been R&D'd to the point of exhaustion. And used by thousands of people.
                          www.realtuners.com - catch the RealTuners Radio Podcast on Youtube, Facebook, iTunes, and anywhere else podcasts are distributed!

                          Comment


                          • #14

                            Re: MegaSquirt and Ignition rev limiters.

                            Re: MegaSquirt and Ignition rev limiters.

                            If you say so, but I will stay N/A ,so I wont be worring about it any more ;D
                            2007 SBN/A Drag Week Winner & First only SBN/A Car in the 9's Till 2012
                            First to run in the .90s .80s and .70's in SBN/A
                            2012 SSBN/A Drag Week Winner First in the 9.60's/ 9.67 @ 139 1.42 60'
                            2013 SSBN/A Drag Week, Lets quit sand bagging, and let it rip!

                            Comment


                            • #15

                              Re: MegaSquirt and Ignition rev limiters.

                              Re: MegaSquirt and Ignition rev limiters.

                              - 80 BTDC, etc
                              :o ???

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