Announcement

Collapse
No announcement yet.

Megasquirt sequential injection

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    Megasquirt sequential injection

    Did any of you guys ever looked at implementing sequential injection for fuel efficiency at low rpm? I looked over the diagrams and if you connect a switching circuit that will switch after every time the injector output is triggered, then, sequential injection can be easily achived. Basically, every bank of 2 injectorw will be split in half so only 1 injector fires at a time.

    Could always use the processor itself but then the PCB needs to be changed, I'd rather use an external switching circuit though, still need to think about what to use for a switching circuit.

    #2
    not really sure its needed.... but if you want sequential injection you should be able to do it with megasquirt 2 and the new router board which is coming out soon.

    matt could tell you more about that...
    Escort GTR -- 11.87 @ 117.6 mph -- 320 HP / 325 Ft. Lbs. @ 23 PSI
    ... The first FWD BG with a Toyota E153 transmission conversion in the USA!
    Looking for BP x Toyota E153 adapter plates? PM me or contact me on Facebook: Riel Performance Parts

    Comment


      #3
      damn, quick reply... looks like MSII has everything already, don't even need to do anything by myself (Just finished EE so would have been an easy fun project). Anyways, I'll search more on the topic and look for the MSII schematics...

      Well, it's not needed in terms of performance but it would be good for fuel efficiency, just open 1 injector instead of 2 all the time.

      Comment


        #4
        Originally posted by 323driver View Post
        Did any of you guys ever looked at implementing sequential injection for fuel efficiency at low rpm? I looked over the diagrams and if you connect a switching circuit that will switch after every time the injector output is triggered, then, sequential injection can be easily achived. Basically, every bank of 2 injectorw will be split in half so only 1 injector fires at a time.

        Could always use the processor itself but then the PCB needs to be changed, I'd rather use an external switching circuit though, still need to think about what to use for a switching circuit.
        There's something you're overlooking. You'd want to time the injection (it would be best to) with ignition such that fuel is injected in each cylinder at the same time in the cycle. You'd have to be able to tell MS and your switching circuit on which of the 4 ignition events to start each time you start your car.

        Comment


          #5
          Yep, your absolutely right, need to time ignition with fuel together. However, but the MS is doing that already, we are just splitting the output in 2. Basically, the main problem is to initialise the splitting circuit in the first place and that can be done using ignition inputs (The MS knows which cylinder to fire so we could use that info to use the injector accordingly). Once you figure out what cylinders starts, the rest is simple. I'm not proposing to control the injector pulses, just to direct them to the appropriate cylinder.

          To John: Which Matt, Cramer?

          Comment


            #6
            The MS does not do that unfortunately - it starts firing on the first ignition pulse no matter what cylinder that ignition pulse is for.

            Comment


              #7
              matt fulghum, the moderator on this forum... he built my MS2. he's got one of the router boards for prototype testing i believe.
              Escort GTR -- 11.87 @ 117.6 mph -- 320 HP / 325 Ft. Lbs. @ 23 PSI
              ... The first FWD BG with a Toyota E153 transmission conversion in the USA!
              Looking for BP x Toyota E153 adapter plates? PM me or contact me on Facebook: Riel Performance Parts

              Comment


                #8
                the MS guys did it on one of their previous project ECUs... it's not worth it. There's no real major benefit to just having the injectors fire at exactly when they're supposed to (as fuel takes time to carburate anyway, and that amount of time varies somewhat depending on conditions) and to individually tune each cylinder properly in order to get any benefit from individual injector trim you'd have to spend countless hours on a dyno with individual EGTs and gas analyzers for each cylinder. It'd be a royal pain in the ass.

                The better way to save fuel would be to lighten up on the right foot.
                Ask me about engine management!

                Comment


                  #9
                  My Link lets me run either sequential or batch fire. if you go sequential, it only applies to the first 20% of duty cyle, after that it switches to batch fire anyhow. That said, there is a pretty big difference in driveablility and mpg. That, and in batch mode I couldn't get the thing to pass emissions not no way no how but in sequential it passed with flying colors. I'm looking at an ECU upgrade for the rallycar so I will pay attention to MS2....
                  '90 AWD Protege, full GTR drivetrain swap, ~320 whp daily driver, RIP, and
                  '90 AWD Protege, yet another GTR swap, Open class rallycar with a Toyota GT4 gearbox swap, thus crossing the line between hobby and mental illness. And a Brabus E55 K8, removing all doubt.
                  http://www.wihandyman.com/forum/vbpi...?do=view&g=110
                  http://www.cardomain.com/ride/2599486

                  Comment


                    #10
                    if only one cylinder is compressing, why have more than 1 injector fire? seems to me if the injectors or batch firing normally, you could increase fuel economy on and off the throttle by going sequential. My GP doesn't batch, it's sequential. hell if it was an '04 instead of an '02 it would shut down 3 cylinders to save more fuel.

                    royal pain in the ass if you like paying for wasted fuel.
                    No car! I soldz it. Now I have a truck. I like it, but apparently it has a hard time keeping up with a slightly modified 4WD protege with half the hp. Neat.

                    Comment


                      #11
                      That's what I was thinking. At low rpm below 2500, i.e. traffic and city driving, there is no need to open 2 injectors while only 1 cylinder is firing. It's true that you can't always open it at an open valve and that there is no point in tunning each cylinder but injecting in a cylinder that is expeling the exhaust gases is worthless as well.

                      How does the MS II start our cars, using the disti(cas) and crank position sensor always starting at cylinder 1? I'll be bying the MSII soon but this issue just annoys me.

                      Comment


                        #12
                        cylinder deactivation is interesting as well, not sure if it's safe or efficient on a 4 banger but you got me thinking...Running on 2 cylinders at idle, always switching pairs, interesting... Nah, not gonna work like Matt said
                        Last edited by 323driver; 12-07-2007, 09:47 AM.

                        Comment


                          #13
                          if you got that big a difference in mpg and drivability and couldn't pass emissions on batch fire, then there was a problem with your settings. The stock ECU uses batch fire, and it passes just fine.

                          There's no inherent problem with batch fire. Sequential just gives you a little more control, but it's not worth spending the very limited I/O on.

                          EDIT:
                          Also, running cylinder deactivation on a four cylinder is a bad idea. Ever lose a cylinder while driving? It's not fun.

                          With just two cylinders (or one) that cylinder would still have to produce enough power to keep the engine turning over at relatively high speed, plus you'd have no way to balance the engine, which leads to extra strain on the internals.

                          On a V8, deactivating a bank of cylinders is fine because you still have 4 cylinders going, which is plenty enough to keep it running relatively smoothly. Plus on the cylinder deactivation systems to my knowledge they shut the valves on the cylinders to reduce losses, which you couldn't do on the BP.
                          Last edited by matt_fulghum; 12-07-2007, 09:44 AM.
                          Ask me about engine management!

                          Comment


                            #14
                            Stock ecu passes emissions w/batch fire. On stock injectors. Couldn't manage that feat with injectors twice the flow of stock...maybe a newer ECU has finer resolution to pass emissions doing batch with 550's, but not my old-ish Link.
                            '90 AWD Protege, full GTR drivetrain swap, ~320 whp daily driver, RIP, and
                            '90 AWD Protege, yet another GTR swap, Open class rallycar with a Toyota GT4 gearbox swap, thus crossing the line between hobby and mental illness. And a Brabus E55 K8, removing all doubt.
                            http://www.wihandyman.com/forum/vbpi...?do=view&g=110
                            http://www.cardomain.com/ride/2599486

                            Comment


                              #15
                              Originally posted by Lex View Post
                              The MS does not do that unfortunately - it starts firing on the first ignition pulse no matter what cylinder that ignition pulse is for.
                              I guess this applies to a disty setup as the disty redirects the pulse to the appropriate cylinder. How does the MS work with wasted spark then? The cylinders are fired 2 by 2 but how to know which coil to fire initially? Same for injection, how do we know which bank to fire first?

                              So basically we need to figure out what cylinder is fired and injected first and then you just follow the firing order, 1, 3, 4, 2. The functionality of the brain is not changed though, just routing the signals.

                              Thanks

                              Comment

                              Working...
                              X