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Bosch 42lb Green injectors maxing out around ~10psi?

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    Bosch 42lb Green injectors maxing out around ~10psi?

    Does this sound right? Stock m20, HX35. MS logs are showing >100% duty cycle. I know MS calculates DC off of a variety of factors and isn't necessary accurate. I was always under the impression that those injectors are capable of quite a lot more than that...

    325iX Turdbo RallyX/Beater/Shuttle Vehicle

    #2
    Gasoline, I assume? When you "run out" of duty cycle, do your AFRs start climbing? Is your fuel pressure manifold referenced? As I'm sure you know, it's impossible to have more than 100% duty cycle.

    10psi doesn't mean much, per se. The injectors you have should get you to around 325whp, I would expect. How fast does the car feel?
    '84 318i M10B18 | 93whp/90ftlbs | 147- Safari Beige | MS2E w/ LC, 2-Step

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      #3
      Yes, Gasoline. The AFR's are where they should be, even when the indicated DCs are through the roof. The fuel system is bone stock m20 stuff.

      The car is pretty fast, butt dyno says 280hp or so, maybe a little more? But who knows...

      325iX Turdbo RallyX/Beater/Shuttle Vehicle

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        #4
        Originally posted by Fraser View Post
        Yes, Gasoline. The AFR's are where they should be, even when the indicated DCs are through the roof. The fuel system is bone stock m20 stuff.

        The car is pretty fast, butt dyno says 280hp or so, maybe a little more? But who knows...
        post your msq and a log
        '84 318i M10B18 | 93whp/90ftlbs | 147- Safari Beige | MS2E w/ LC, 2-Step

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          #5
          if your injector constants are not right, the duty cycle will be wrong. If you're seeing duty cycle over 100% then you need to readjust the constants. This will also likely require VE table adjustments.
          Build thread

          Bimmerlabs

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            #6
            Originally posted by nando View Post
            if your injector constants are not right, the duty cycle will be wrong. If you're seeing duty cycle over 100% then you need to readjust the constants. This will also likely require VE table adjustments.
            Forgive my ignorance, but specifically what settings need to be looked at on the constants page?

            I'll post an MSQ and log later this afternoon, I need to grab my computer from the shop to look into this further. Thanks!

            325iX Turdbo RallyX/Beater/Shuttle Vehicle

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              #7
              check your fuel pressure too, maybe something pump or regulator related
              Originally posted by priapism
              My girl don't know shit, but she bakes a mean cupcake.
              Originally posted by shameson
              Usually it's best not to know how much money you have into your e30

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                #8
                if it reads 100dc+ yet it still responds to increasing ve
                then it is not at 100.

                idk the limits of the stock pump or the draw but i do know the stock wiring sucks
                and if u wire the pump from the batt. on a relay it will get you where you need to be.
                if not for this then for future pump needs. stock wiring is shit.
                my 255 was going lean and wiring it this way gave me that extra needed fuel

                10psi on stock hx35 setup i don't think you are maxing them out.

                i am rusty on MS settings but your dead time and fuel requirements are not right.
                Last edited by LowR3V'in; 03-12-2019, 08:30 PM.

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                  #9
                  Thanks for the info- that's not the first time I've heard it's wise to rewire the pump with it's own circuit and relay.

                  Here is a link to the current tune and a couple logs- one is ~12 psi and is busting 100 DC, another is back down to 10psi and still hitting near 90, which I do not believe to be correct. Thanks to whoever is interested in looking at them...

                  https://drive.google.com/open?id=1rI...nkCkbqFZZT2xzv

                  325iX Turdbo RallyX/Beater/Shuttle Vehicle

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                    #10
                    9.8arf @ 11psi it's drowning.

                    Even your targets are 11.5afr that is way too rich for the boost.
                    try 12.5 afr.

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                      #11
                      Originally posted by LowR3V'in View Post
                      9.8arf @ 11psi it's drowning.

                      Even your targets are 11.5afr that is way too rich for the boost.
                      try 12.5 afr.
                      Geez, no kidding. I've been running around at 6-7 psi for so long while I was troubleshooting a spark miss I guess I never noticed those higher boost squares running so rich. Obviously that would explain the duty cycles being so high in those same areas also.

                      I'll work on those tables a bunch over the next few days and see what it looks like.

                      Thanks for your help!

                      325iX Turdbo RallyX/Beater/Shuttle Vehicle

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                        #12
                        Shoot me a datalog with the current .msq, last one said 65% if memory serves me correctly. I owe ya a beer/soda. :p
                        john@m20guru.com
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                        Transaction feedback: Here, here and here. Thanks :D

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                          #13
                          Originally posted by ForcedFirebird View Post
                          Shoot me a datalog with the current .msq, last one said 65% if memory serves me correctly. I owe ya a beer/soda. :p
                          Will do- I love beer! I think my current overfueling issues had to do with hitting KPA values that hadn't been hit before and were thus tuned conservatively (really) rich...

                          I'll send over the most recent log and MSQ and see what you think... I'd like to run 12-14psi regularly which looks like shouldn't be a problem with the current hardware once I get the tune a little more dialed. Other than my stock clutch which is starting to slip like a bastard and needs to be replaced ASAP.

                          Thanks guys!

                          325iX Turdbo RallyX/Beater/Shuttle Vehicle

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                            #14
                            I was going to say.... our altitude and 10psi shouldn't be pushing those injectors! I downsized to 30#'s on my M30 to try and have excellent performance throughout operation for my car up to 160kpa.
                            http://www.Drive4Corners.com

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                              #15
                              Wow, how much power are you running on the 30#s? I would consider going to smaller injectors at some point to get some of my cold start issues cleared up...

                              325iX Turdbo RallyX/Beater/Shuttle Vehicle

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