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Speeduino build for M20B25

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    #16
    Thanks a bunch! Looking forward to this project. I just started buying parts for my build. They'll probably come in month or so.

    Am also pretty interested in launch control/flat shifting. Although not entirely sure what are the benefits but will probably look into it later on. I heard you could use the brake switch for it.

    Apart from that, am actually quite interested in the capabilities of the HC-06 bluetooth module.

    I have never tuned a car before (will have to get myself educated more on that later as well. Could you share more details about this timing light please? I thought there is a Crankshaft Position Sensor (CPS) that will be converted to something the Arduino can read by using the VR Conditioner and this would tell timing?

    No worries, you've helped plenty!

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      #17
      Originally posted by ecnerettee View Post
      Thanks a bunch! Looking forward to this project. I just started buying parts for my build. They'll probably come in month or so.

      Am also pretty interested in launch control/flat shifting. Although not entirely sure what are the benefits but will probably look into it later on. I heard you could use the brake switch for it.

      Apart from that, am actually quite interested in the capabilities of the HC-06 bluetooth module.

      I have never tuned a car before (will have to get myself educated more on that later as well. Could you share more details about this timing light please? I thought there is a Crankshaft Position Sensor (CPS) that will be converted to something the Arduino can read by using the VR Conditioner and this would tell timing?

      No worries, you've helped plenty!
      For flat shift/launch control the clutch switch is used. Haven't had a chance to play around with it on my car because I never added a clutch switch when I swapped it from auto to manual.

      The timing light is needed to set your trigger angle properly. This is how the ECU knows the position of your engine. For example if my trigger angle is off 30 degrees. Everything in my ignition table will be off by that much. So you typically want to set the trigger angle right at TDC so that your ignition table is accurate. You use a timing light to see if the setting you configured in your ECU is accurate to actual TDC.

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        #18
        I actually just wired in my clutch switch with my megasquirt build, as well as got most of the pieces into place for traction control, launch control and flat shifting as well. It will be a little while before I actually test it though, lots of other items on the list at the moment.

        If your car had/has cruise control, and is manual, there should be a clutch switch.

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          #19
          Originally posted by JehTehsus View Post
          I actually just wired in my clutch switch with my megasquirt build, as well as got most of the pieces into place for traction control, launch control and flat shifting as well. It will be a little while before I actually test it though, lots of other items on the list at the moment.
          How did you use the clutch switch for MegaSquirt?

          As you said, any manual transition car with cruise control has a switch on the clutch pedal. Unfortunately, the circuit is grounded when the pedal is up and the circuit is open when the pedal is pressed (the opposite of how MegaSquirt needs it). I'm looking into the following options:
          • Switch to a single pole dual throw (SPDT) switch: cruise control gets grounded until I press the clutch, then MegaSquirt gets grounded. I bought a switch, but it seems too small and I don't like it.
          • Add a second switch that closes the circuit when the pedal is pressed
          • something else?
          sigpic
          1987 - 325i Convertible Delphin Auto [SOLD], 325i Convertible Delphin Manual [SOLD]
          1989 - 325i Convertible Bronzit m30b35 swapped [SCRAPPED], 325i Sedan Alpine Auto[DD]
          1991 - 325i Coupe Laguna Manual [Project], 535i Sedan Alpine [SCRAPPED]

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            #20
            Originally posted by McGyver View Post
            How did you use the clutch switch for MegaSquirt?

            As you said, any manual transition car with cruise control has a switch on the clutch pedal. Unfortunately, the circuit is grounded when the pedal is up and the circuit is open when the pedal is pressed (the opposite of how MegaSquirt needs it). I'm looking into the following options:
            • Switch to a single pole dual throw (SPDT) switch: cruise control gets grounded until I press the clutch, then MegaSquirt gets grounded. I bought a switch, but it seems too small and I don't like it.
            • Add a second switch that closes the circuit when the pedal is pressed
            • something else?
            I don't think the MS cares, does it? I have not actually configured it yet but I can see the I/O switching. Worst case I should be able to invert it with a loop. (I am running an MS3 ultimate).

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              #21
              Overthinking.

              MS simply has an open to closed, or closed to open parameters. The type of switch is irrelevant. When doing launch/traction, the ECU simply needs to know the condition specified, and act upon it. In the end, it is user-defined.
              john@m20guru.com
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              Transaction feedback: Here, here and here. Thanks :D

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                #22
                Originally posted by ForcedFirebird View Post
                Overthinking.

                MS simply has an open to closed, or closed to open parameters. The type of switch is irrelevant. When doing launch/traction, the ECU simply needs to know the condition specified, and act upon it. In the end, it is user-defined.
                Yeah, I figured it shouldn't matter. What does matter, from my understanding, is where the switch is 'tripped' relative to clutch position (and it being adjustable). The factory switch is adjustable. What I don't like is that the bracket holding it seems rather 'floppy'... for example, my switch wasn't working, took a look at it and realized the bracket was bent and it was sitting way back, bent it back and now it seems fine. Not really what I want for a setup beyond basic validation/screwing around, so I will need to fix that.

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                  #23
                  Originally posted by ForcedFirebird View Post
                  Overthinking.

                  MS simply has an open to closed, or closed to open parameters. The type of switch is irrelevant. When doing launch/traction, the ECU simply needs to know the condition specified, and act upon it. In the end, it is user-defined.
                  Ok, so you're saying that I use my stock clutch switch, which is grounded with the clutch engaged and open with the clutch pedal pushed. Then I set it in MegaSquirt to say, "turn on Launch control when you see an open circuit, turn it off when you see ground".

                  That's so simple. I overthink stuff way too often.




                  Attached Files
                  sigpic
                  1987 - 325i Convertible Delphin Auto [SOLD], 325i Convertible Delphin Manual [SOLD]
                  1989 - 325i Convertible Bronzit m30b35 swapped [SCRAPPED], 325i Sedan Alpine Auto[DD]
                  1991 - 325i Coupe Laguna Manual [Project], 535i Sedan Alpine [SCRAPPED]

                  Comment


                    #24
                    One thing I found with two-step on my car is that the stock clutch switch is not well suited for it. If you have the clutch depressed AT ALL, even a little bit, the switch will activate. What I found is that unless I took my foot fully off the clutch pedal between shifts, I was frequently activating two-step when I didn't want it active, just by applying the slightest pressure to the pedal. During autocross, when it's not really practical to take your foot off the pedal (because you are shifting very often), it was a pain in the ass.

                    For track use and flat foot shifting, that might work fine.

                    For autocross and two-step, you probably want a bottom mounted switch that will only be active when you really want it to be; clutch fully depressed to the floor.

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                      #25
                      Updated the original post with more details on idle control and trigger angle now that I have a timing light. Got wasted spark working and 60lb injectors running, so going to add details soon. Slowly putting together a turbo kit, so hopefully by summer I'll have boost control working. Car was running fine and I actually took it for a drive. Autotune seemed to dial the AFR in pretty well but with stock injectors, but I was seeing VE table values ~145 at 4400rpm 100kpa which seems really high. I think the reason for that was because I had my injector settings wrong. Upgraded to Simens Deka 60lb injectors so we will see how that goes.

                      Ran into a really interesting issue when setting up wasted spark. With the stock cap/rotor using the timing light trigger angle was 50, and the car ran fine. When I moved over to wasted spark I had issues cranking the car over, it would just backfire when cranking. Pulled the timing light back out and tried to verify my trigger angle again and it changed from 50 to 276. Not sure what caused this change or why the trigger angle is different from the stock cap/rotor setup, anyone have any ideas? I used the same timing light, and checked both cap/rotor and wasted spark trigger angle on the same day.

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                        #26
                        Finally got the car turboed, and started working on getting it tuned. First time I decide to get into boost my crank position sensor decided to fail, which was a pretty scary experience on the road. As I was doing a pull the car felt like it cut out and then backfired super loud. You can see what happened in the logs.
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                        The crank position sensor would short out when I wiggled the wire, and the resistance was ~930 ohms which is out of spec which I think is 530 ohms. I had a spare CPS laying around so went ahead and swapped it, not sure how soon this one will fail, it's definitely not the oem metal one. It read 540 ohm and the car cranked. Does anyone have suggestions for a replacement brand just incase? Seems like the OEM sensor is ~$170 which seems pricy.

                        Also is it normal to have some sync loss when first cranking the car? Here is an example log from the car cranking.
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                        I plan to wire up oil and fuel pressure sensor, and a boost controller this weekend. Once I get everything working I'll update the thread.

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                          #27
                          OEM is the only reliable way to go. The M42's OEM one is well north of $200, so $170 is not too bad overall. It'll last another 3 decades anyway. Hopefully the head gasket was not damaged when the ECU lost sync with crank position. I suspect that my engine's HG was done-in when I had a similar issue (the sensor was OK, but the rubber ring holding the toothed wheel to the hub came apart). It took ~4 months for the HG fully blow after the backfire incident I had, but it never quite ran right during that time, so keep an eye on coolant levels and listen for any "excessive" exhaust noises. You're probably fine though, so hopefully it was just raw fuel in the exhaust getting lit up.

                          What are your overall impressions of how the car runs on Speeduino, particularly idle and throttle tip-in?

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                            #28
                            Originally posted by bmwman91 View Post
                            OEM is the only reliable way to go. The M42's OEM one is well north of $200, so $170 is not too bad overall. It'll last another 3 decades anyway. Hopefully the head gasket was not damaged when the ECU lost sync with crank position. I suspect that my engine's HG was done-in when I had a similar issue (the sensor was OK, but the rubber ring holding the toothed wheel to the hub came apart). It took ~4 months for the HG fully blow after the backfire incident I had, but it never quite ran right during that time, so keep an eye on coolant levels and listen for any "excessive" exhaust noises. You're probably fine though, so hopefully it was just raw fuel in the exhaust getting lit up.

                            What are your overall impressions of how the car runs on Speeduino, particularly idle and throttle tip-in?
                            Headgasket is fresh with ARP studs holding it down, so hopefully didn't do too much damage. Idle is great, throttle tip in needs work, but I don't have acceleration enrichment dialed in or know what I'm doing with it. Here is what my acceleration enrichment looks like in settings.
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                            I'll run with this spare CPS I have for as long as it works, and if it fails I'll get the OEM one. Updated the settings in my ignition table to not have negative timing if it was to lose sync again. Here is my ignition table currently, does any of this look too aggressive? I'll be making a set of knock cans soon so I can listen for knock.
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                              #29
                              Got the fuel pressure sensor and boost controller installed and wired this weekend, still waiting for my adapter for the oil pressure sensor. Wiring was pretty straightforward for both.

                              The boost controller I'm using is a MAC 3 port 35A-AAA-DDBA-1BA. Looks like this and only has two wires. One of the wires went to a switched 12v, and the other one goes to the pin on the ECU that is labeled boost.
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                              I have it plumbed to my wastegate like the image below.
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                              For the fuel pressure sensor I used the holes that are under the arduino on the ecu and soldered wires in for the 5v, ground, and a6. Put a 2.2k resistor between the a6 pin and the signal wire. Not posting pictures because it looks pretty bad so I'll probably redo it sometime.
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                              Trying to used the closed loop and running into issues. Here are my settings.
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                                #30
                                The issue I'm having is overboost, I end up hitting my boost cut, maybe this table is looking for boost targets only and not the map targets? So instead of 136kpa I should have 36kpa, need to test that out. Looking at the logs it looks like when I hit 136 the duty cycle stays at 40 (I actually had 40 as the max in my settings at the time of this log). Looks like fuel pressure kind of bounces around. I'm wondering if this is because of my sensor reading weird or the fuel pressure is actually doing that.
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                                Random thing not relating to the ECU. It seems like after turboing the car my oil cap is leaking oil, I have valve cover vented to atmosphere so not sure why it's leaking. Took a bike innertube and made a gasket for it, hopefully that helps.
                                Last edited by sk8; 03-23-2021, 09:50 AM.

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