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JT's M20 Build Thread

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    Not much of an update; stuck working on the chicken coop all weekend. I did pull the car out of the shop and roll it on down the (fairly steep and long) hill. Brakes felt great...yet to see how it is while actually driving but I now have no concern they will stop the vehicle without insane pedal force.


      How did the brakes go ?
      89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...

      new build thread


        Originally posted by digger View Post
        How did the brakes go ?
        I wish I could answer this... just rolled the car back into the shop late last week. Long story short, just switched jobs (actually remotely working for an american company now, yay for getting paid in USD! Lots of hoops to jump through though, setting up a company and everything else is a pain in the ass the first time around).

        All I can say is that brakes feel totally fine at ~20km/h speeds moving down a 50ft hill, and seem great very functional moving the car around the property unpowered, which is pretty useless information, but does mean I didn't totally fuck up the numbers. Much easier to use than the factory boosted brakes without the booster, but definitely a little more work than the brakes with the booster (mostly because you have to hold it, the booster doesn't do all the work for you at low force levels). Pedal travel sitting still and putting a fair bit of force on them does not seem excessive, but it remains to be seen if that translates to stopping the car comfortably from speed or not.

        Most of the work on the car is done at this point, I am just trying to locate a decent option for a transmission jack so I can pull the trans again and put in the pilot bearing I forgot... Otherwise there is a little finagling to do to fit the exhaust, need a couple more fittings for my fuel system adventures, dropping in the rad... then just finishing off the wiring harness, but I think that will be no more than a weekend plus an afternoon or two, most of the hard work (i.e. mapping the I/O) is done and it is hopefully just connectors at this point. This is all while making sure the lady stays happy.

        I also have some more 'want to do's' to tackle, which I may or may not take a stab at before startup. This includes a rust hole in my passenger floor, probably right where the drain is.

        Speaking of wiring, if anyone is interested here is my current plan of attack with the MS3 pro in terms of what I am doing with the connector signals...

        Long story short plan is for single turbo, possibly water/meth injection. Those signals are reserved here. I have also made a reservation just in case I want to run twin blowers but I seriously doubt I will, I am leaning towards twin scroll with possibly a recirculating/bypass valve setup.
        I am also aiming to have full 4 wheel traction control, so I am going to either replace ABS sensors with hall sensors or use a VR to hall converter to get 4 wheel VSS.
        There are bosch PTS sensors on oil, coolant and fuel. If I do instrument and log brakes it will be through a separate system, as those have no relevance to engine control.
        With the instrumentation and control setup below I should also be able to do launch control, we will see how that turns out.

        White Connector:
        MS3 Pin MS3 Function Connected To Notes
        1 High current out 1 RESERVED
        (Boost Control Solenoid)
        Control signal for boost regulation SS relay.
        2 High current out 2 RESERVED

        (Optional second solenoid)
        Unlikely - only if running TT.
        3 Injector out J Oil Pressure C101 Pin 5 (Brn/grn), ground switched oil pressure light in cluster. Ground is oil pressure OK.
        4 Injector out I Check Engine Light C101 Pin 12, check light.
        5 High current out 3 RESERVED

        (Meth/water pump output)
        Control for water injection pump relay. May end up unused, depending on detonation likelihood under E85.
        6 CKP+ Crank Position Hall CPS also uses 5V+ VREF 1
        7 Knock In 2 N/C
        8 5V+ VREF out 1 Power for Some Sensors Used only for CKP and CMP sensors.
        9 TPS in TPS Input TPS also needs 5V+ VREF 1
        10 MAT in IAT sensor signal side
        11 CLT in PTS (Clt), Temp. May need to change internal pullup from 2.49k to 4.9k.
        12 Analog In 6 Launch Control Adjustment Input Used to adjust launch control setpoint.
        13 Power ground Ground Block
        14 PWM / Idle Out 1 IAC valve Open side of bosch IAC valve
        15 CKP- N/C No connection - do NOT ground
        16 Logic ground * Ground Block
        17 Analog In 7 Ambient air temp Ambient air temperature sensor.

        Note: May also move to pre-IC charge pipe once turbo is setup.
        18 Sensor return CKP and CMP Ground wire for CKP and CMP only, should help keep any hall switching noise off other sensors.
        19 Analog in 1 PTS (Clt) Press.
        20 Analog in 2 PTS (Oil) Temp. 4.9K pullup to 5V+
        21 Analog in 3 PTS (Oil) Press.
        22 Analog In 4 PTS (Fuel) Temp.. 4.9K pullup to 5V+
        23 Analog In 5 PTS (Fuel) Press..
        24 Tach out C101 Pin 9 (black) Inst. Clust. Tachometer
        25 O2 in WBC LC2 Analog #1 Wideband O2 needs to be setup
        26 CMP+ Cam Position Hall CMP also uses 5V+ VREF 1
        27 CMP- N/C No connection - do NOT ground
        28 Fuel pump relay out Fuel Pump Relay Ground side of FPR.
        29 PWM out 2 IAC valve Close side of bosch IAC valve
        30 PWM out 3 RESERVED

        (Meth/water valve control)
        High frequency control for water injection valve. May be unused.
        31 Knock in 1 Knock Sensor
        32 Digital switched in 1 Flex Fuel Sensor Flex fuel sensor output
        33 CAN L N/C Possibly route through C101 for future IC changes.
        34 CAN H N/C
        35 12V+ switched power in Main relay out C101 P7 actually drives the main relay, which drives this. (Relay needs rewiring)
        Grey Connector
        MS3 Pin MS3 Function Connected To Purpose
        1 Injector out A Cyl. 1 Injector
        2 Injector out B Cyl. 5 Injector
        3 Ground Ground Block
        4 Injector out C Cyl. 3 Injector
        5 Ground Ground Block
        6 Injector out D Cyl. 6 Injector
        7 Ground Ground Block
        8 Injector out E Cyl. 2 Injector
        9 Ground Ground Block
        10 Injector out F Cyl. 4 Injector
        11 Injector out G Fan Relay Control Used to control electric fan.
        12 Injector out H O2 Relay Control Allows for keeping wideband on when needed, such as during idle tuning. Normally will operate with the same logic as the FPR control.
        13 Spark out G N/C
        14 Spark out E Coil Pack Ign. Cyl. 2
        15 Spark out C Coil Pack Ign. Cyl. 3
        16 Spark out H N/C
        17 Digital frequency in 2 Unused (VR mode)
        18 Ground Ground Block
        19 Digital switched 12V in Main relay out
        20 Digital switched in 2 RESERVED

        (4W traction control)
        21 Digital frequency in 3 RESERVED

        (4W traction control)
        22 Digital Frequency in 3 VR+
        23 Digital Frequency In 3 VR-
        24 Spark out F Coil Pack Ign. Cyl. 4
        25 Spark out B Coil Pack Ign. Cyl. 5
        26 Spark out D Coil Pack Ign. Cyl. 6
        27 Spark out A Coil Pack Ign. Cyl. 1
        28 Digital frequency in 1 E30 cluster speed/
        wheel speed for TC
        * If not filtered - if so pickup directly off differential VR sensor
        29 Digital switched in 3 RESERVED

        (4W traction control)
        30 Stepper IAC out 1B
        31 Stepper IAC out 1A
        32 Stepper IAC out 2A
        33 Stepper IAC out 2B
        34 Digital Frequency in 1 VR+
        35 Digital Frequency in 1 VR-
        Black Connector
        MS3 Pin MS3 Function Connected To Purpose
        1 PWM out 5
        2 PWM out 4
        3 Digital out 2 Traction Control Light
        4 Digital out 1 Shift Light
        5 Digital I/O 4
        6 Digital I/O 2 Clutch Switch Clutch pedal engaged switch
        7 Analog in 8 Traction Control Setting Use for analog traction control adjustment.
        8 5V+ VREF out 2
        9 Fuel only coil negative unused (?)
        10 Digital switched in 5
        11 Digital switched in 4 LC enable switch
        12 Digital I/O 5 RESERVED

        (Meth/water reservoir level warning switch)
        Fluid level warning sensor for water reservoir. May be unused.
        13 Digital I/O 3
        14 Digital I/O 1
        15 5V+ VREF out 2
        16 Fuel only battery 12V+ Fuel Pump Power Switched by FP relay.
        17 Sensor return Ground for all PTS sensors, TPS and IAT CLT, Fuel, Oil and eventually brake sensors will all share this ground.
        18 Sensor return Ground for Knock sensor
        19 Sensor return Ground for all other engine aux. This includes E85 sensor, any other low current signal grounds.
        20 Sensor return
        21 Sensor return
        22 5V+ VREF out 1 Used for TPS, all PTS sensors.
        23 Keep alive power 12V+ Terminal


          Managed to knock off one of my items tonight, and that was getting the fuel rail properly mounted. The Nuke fuel rail is substantially larger than the factory one - it is roughly 0.7" internal diameter, and while I didn't bother measuring it against the factory rail, suffice to say it is much bigger.

          I went through a few different attempts to get it to seat properly - first two tries I was avoiding modifying the manifold, and long story short I could not get it to work, the angle of the injectors was just wrong.

          Tonight I pulled the manifold and cut/ground down the fuel rail mounting points until they were essentially flush with the weird crosshatching on the manifold. This had two advantages - it let me angle the rail correctly (or at least as close to correct as I can figure. The injectors may even be a little bit further angled, I don't have the best reference material. If that is the case it is easy enough to shim with some washers, and maybe if I feel like burning extra money at the dyno I could try a couple slightly different angles and see if it makes any meaningful difference.

          Anyway, here is some eyecandy:

          Aluminium shavings EVERYWHERE, naturally. Cleaned everything out as best I could, obviously, even with the covers some still got in.

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          I also had to adjust the rail so it would clear the Bosch PTS. Bit of a chonky bastard compared to the factory temperature sensor. Anyway, it barely fits with room for the connector now.

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          Vacuum lines are also pretty much all in place. The vac station pics up off the throttle body with the 6-AN fitting, and the two 4AN lines on the bottom run off to the MAP sensor and FPR respectively.

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          I would like to get the majority of the coolant hoses loosely in place tomorrow, along with the return fuel line, and hopefully locate my other Y fitting which has mysteriously disappeared so I can completely wrap up the fuel system (in the engine bay). At that point I can basically go to town wiring, although I do still need a few bits from Digikey which I will get in early next week.

          Note that I will be replacing the radiator with something more suitable relatively soon in the future; I just want to nail down an intercooler so I can make sure the two of them play together nicely in the available space. There is a 2000 CFM SPAL hiding behind the radiator rather poorly mounted at the moment, which I am controlling electronically via the MS.

          I also need to get a factory valve cover vacuum hose - bend is a bit tight for the hose I have that fits over the breather. I will likely cut it off after it exits the manifold area and wrap it in a separate hose that I can route to the catch can, unless anyone has any better suggestions.


            Put in a solid couple of days on the wiring this weekend. Managed to accomplish the following:
            • Relay wiring changes to power the Megasquirt. Also decided to power the fuel injectors from the FP relay, as recommended per the MS documentation, which is a bit different from the factory setup where, to my understanding, they are powered off the main relay.
            • MS powers up when the key is on. Very nice to have this functioning so that you can easily sanity check sensors as you wire them in.
            • Intake air temp is wired. Needs calibration (I have already got the necessary docs from ID, so I just need to get around to generating the MS INF file for the sensor), but a heat gun blowing hot air into the throttle body shows very definite movement in the upward direction.
            • ICV is wired. Quick test of trying to blow through the valve indicates the MS open and closed positions are setup correctly, although I have not actually verified PWM range (i.e. is valve only opening to 50% or 100% when the MS thinks it is at 100%?)
            • TPS is wired. Also adjusted throttle set screw so that there is ~0.003" of clearance between the plate when the throttle is closed. Is this the correct clearance? I was also reading 0.015" somewhere. I am also seeing a range of 1-708 ADC counts, not roughly 1023. I haven't actually done the math WRT the resistance range of the TPS, does this seem correct or is it potentially a problematic TPS?
            • C101 connector is fully wired and integrated into the harness. Interesting tidbit that I did not realize - C101 on the early models doesn't include the tach signal pin, this comes off a separate connector that runs under the dash. Which I specifically remember thinking was some aftermarket garbage piece (when I was pulling factory ECM) that somebody had installed for some reason when they wired in the aftermarket radio.
            • Injectors are all wired. Have not actually ran through and manually tested/listened for clicks yet though.
            • The Bosch PTS sensor for the coolant is wired and crudely tested (it needs calibration as well, I have not created the custom calibration file for it yet). The NTC does respond as would be expected to touch though, and if I blow on the sensor I can get the pressure reading to jump up a small amount.
            • Factory connector for the instrument cluster temperature sensor is in the harness and ready to be plugged in. Keep forgetting to bring the sensor from the house to the shop, but I am not really too concerned about getting it working.
            • Flex fuel sensor is wired. There is not fuel in the lines (in fact, I have not actually connected the return to the hardline yet), but it reads 0-1% ethanol content and temperature readings look realistic. A heat gun on very low in the vicinity for a couple minutes moved the temp up 5 degrees, which I confirmed came back down after a bit.
            • Starter and alternator. I did not actually test the starter yet, I have not put any clutch fluid in and I would rather not turn anything over (other than by hand) until I get the trans out and install the pilot bearing I forgot.
            This all leaves a decent amount still to do (the above really did take me basically 2 full days of work, thankfully the lady is being understanding)"
            • Bosch PTS on the fuel filter.
            • Bosch PTS on the oil tee (capped for now, but will eventually feed the blower) where the old oil pressure switch was.
            • SPAL fan wiring.
            • Wideband O2.
            • All six coilpacks (trigger, grounds, power and plug wiring).
            • Crank and cam position sensors.
            • Tach.
            • Knock sensor.
            • All the other little goodies, like wheel speed sensors and interior bits such as the clutch switch. These I will wait on though, big focus is core engine control stuff at the moment, then getting trans sorted. Plus I need to figure out connectors and an adapter place for the hall sensors I am planning on using, plus there is some testing to be done to determine if they will work with the factory ABS reluctor rings or not (dimensions are close, but not in the 'ideal' range, so it remains to be seen if it is good enough).
            Where I left things for the night:

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            You can see the coolant PTS sensor on the shock tower.

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            Here it is installed, and some of the injectors.

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            Pins for the Bosch connectors (same style for injectors and for the PTS). While I am quite happy with how these turned out, they are slooooow to do with the wrong tools and a soldering iron.

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            One more shot of the shiny goodness.

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