MS3 + MS3X + BMW M50

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dave.a.cote
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MS3 + MS3X + BMW M50

Post by dave.a.cote »

Just want to check to make sure I am doing everything correctly. I want to run full sequential COP on my non-vanos BMW M50 engine. I tried to do everything in the stock ecu case but I ended up a little too tall so I will have to make a custom lid.

The engine I am using will have:
Stock BMW M50 COP's
60-2 crank trigger wheel with VR sensor
1 tooth cam wheel with VR sensor
3-wire PWM IAC
Firing order is 1-5-3-6-2-4

I am using the ignition outputs A through F on the MS3X going to 6 330 ohm resistors and then to the left pin on 6 coil drivers sold by glens garage. The middle pin goes to the harness and the right pin goes to ground. I currently have this as ground on the MS3X but after some more reading it looks like it should go to ground on the engine.

I have the pots for both the crank and cam sensors turned counterclockwise.

I used some of Goathumpers megasquirt-M50 instructions but tried to update them for the MS3/X setup. The first number is the pin on the BMW harness followed by a description. The last number is where it goes on the V3 mainboard or MS3X expansion board.

I am not sure if I have FIDLE and IDLE the correct way or backwards - can I switch them in the software?

BMW M50 88-PIN
1 - FUEL PUMP RELAY - V3 #37
2 - FIDLE - V3 #30
3 - FUEL INJECTOR 1 - A - MS3X #19
4 - FUEL INJECTOR 3 - C - MS3X #13
5 - FUEL INJECTOR 2 - E - MS3X #7
6 - GND - V3 AND MS3X
12 - TPS - V3 #22
23 - COIL 2 - SPARK E
24 - COIL 3 - SPARK C
25 - COIL 1 - SPARK A
28 - GND - V3 AND MS3X
29 - IDLE - MS3X #9
31 - FUEL INJECTOR 5 - B - MS3X #16
32 - FUEL INJECTOR 6 - D - MS3X #10
33 - FUEL INJECTOR 4 - F - MS3X #4
34 - GND - V3 AND MS3X
37 - GND - V3 AND MS3X
50 - COIL 4 - SPARK F
51 - COIL 6 - SPARK D
52 - COIL 5 - SPARK B
59 - TPS 5V - V3 #26
67 - CRANK VR SENSOR - V3 #24
68 - CAM VR SENSOR - MS3X #32
70 - OXYGEN SENSOR - V3 #23
71 - SENSOR GROUND - V3 #2
74 - TACH OUT - MS3X #26
77 - INTAKE AIR TEMP - V3 #20
78 - COOLANT TEMP - V3 #21

Can someone in the know please give me any tips before I start installing this setup?
hassmaschine
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Re: MS3 + MS3X + BMW M50

Post by hassmaschine »

nice work. I've been working on my own setup, that will go into an E30. I want to use the M50 harness to run full sequential on an M20. Here's what I've got so far..
http://www.megasquirt.325ix.com/MS_to_M ... 3.3.1.html

still need to double check it for errors and clear up a few things.
dave.a.cote
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Re: MS3 + MS3X + BMW M50

Post by dave.a.cote »

Hey that looks pretty familiar. I just flipped through it quickly and see a few differences - you must be using a M50TU harness, right? That would account for differences between coil/injector positions as well as hall instead of VR sensors.

Do you know what kind of output the VSS from the cluster has?

Mine is going in an e30 also - non-vanos 2.9 with dual intake cams, 11:1 compression plus the regular bolt ons.
hassmaschine
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Re: MS3 + MS3X + BMW M50

Post by hassmaschine »

dave.a.cote wrote:Hey that looks pretty familiar. I just flipped through it quickly and see a few differences - you must be using a M50TU harness, right? That would account for differences between coil/injector positions as well as hall instead of VR sensors.

Do you know what kind of output the VSS from the cluster has?

Mine is going in an e30 also - non-vanos 2.9 with dual intake cams, 11:1 compression plus the regular bolt ons.
yeah, I used the ETM from a vanos M50 to develop my chart. I'll have to compare with your chart to see what differences there are, I'm not sure yet which harness to use.

should be a 5v square wave. it's already conditioned by the cluster to send to the OBC and ECU, so it shouldn't need anything else, just plug it into a spare input and call it a day. :)

the interesting thing is I'm sort of doing an M50 swap, as far as electronics are concerned. It just didn't make sense to try to add 5 spark outputs and 4 injector outputs to the motronic 1.3 harness, when M50 harnesses are $100 and have all that stuff already. I want to build the MS3 ECU from scratch anyway, then I can sell my MS2 and modified harness together.
bmbelo
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Re: MS3 + MS3X + BMW M50

Post by bmbelo »

I have a similar setup going into a M50TU. Had problem with those same instructions from Goathumper...my problem was I had a SIEMENS M40 ECU, which means different pinout. The rest sounds good.

Nice work!
Those who can do, those who can't talk about it. - Colin Chapman
dave.a.cote
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Re: MS3 + MS3X + BMW M50

Post by dave.a.cote »

I am using a non-vanos harness. After flipping though a couple other threads I think I might change my idle setup to use two outputs on the 3x instead of 1 on the 3x and one on the mainboard.
howelll
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Re: MS3 + MS3X + BMW M50

Post by howelll »

hello, im new here. i am building a ms3/ms3x for a m52 to go in my e30. i was wondering how you build your 3wire pwm circuit. Do you install Q2 and Q4 on the mainboard, or is the circuit built on the ms3x board?
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Re: MS3 + MS3X + BMW M50

Post by jsmcortina »

howelll wrote:hello, im new here. i am building a ms3/ms3x for a m52 to go in my e30. i was wondering how you build your 3wire pwm circuit. Do you install Q2 and Q4 on the mainboard, or is the circuit built on the ms3x board?
For 3 wire idle you can use two outputs on the MS3X. The mainboard components aren't needed, but you might as well install them for completeness (i.e. install them as standard - don't do the 'mods' with a TIP122 etc.)

James
I can repair or upgrade Megasquirts in UK. http://www.jamesmurrayengineering.co.uk

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hassmaschine
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Re: MS3 + MS3X + BMW M50

Post by hassmaschine »

dave.a.cote wrote:I am using a non-vanos harness. After flipping though a couple other threads I think I might change my idle setup to use two outputs on the 3x instead of 1 on the 3x and one on the mainboard.
I think it makes the most sense to do it this way.. The only reason I wouldn't is if you needed all of those other MS3x PWM outputs for other functions. I wasn't at first, but this way I can completely eliminate the GG idle board I'm using now and significantly clean up my wiring.

BTW I've also created a C101 to X20 chart for a '90 E30 and 93-95 E36, and have uploaded my full excel spreadsheet as well:
http://www.megasquirt.325ix.com/MS_to_M ... 20X20.html
http://www.megasquirt.325ix.com/MS_to_M ... c%203x.xls
hassmaschine
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Re: MS3 + MS3X + BMW M50

Post by hassmaschine »

bmbelo wrote:I have a similar setup going into a M50TU. Had problem with those same instructions from Goathumper...my problem was I had a SIEMENS M40 ECU, which means different pinout. The rest sounds good.

Nice work!
if it's 88 pin it shouldn't matter what ECU you use, since you're using only the connector from the ECU and gutting all the electronics.
dave.a.cote
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Re: MS3 + MS3X + BMW M50

Post by dave.a.cote »

So I finally have the engine sitting in the car and was trying to check some wiring and now have myself completely confused.

I don't know what the deal is with the 2n2222a and the 1n4001 as shown here - what are they for?

http://www.megasquirt.325ix.com/MS_to_M ... rcuit.html

I thought that pin 54 on the m50 harness would be switched 12v power and so I connected it to pin 28 on MS3.

When I switch on the key however, I get 0 volts on pin 54 of the m50 harness. Can you help out?
hassmaschine
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Re: MS3 + MS3X + BMW M50

Post by hassmaschine »

they trigger the main relay

see:
http://www.megasquirt.325ix.com/MS_to_M ... rcuit.html

you can't power the harness your way, since the key sends a signal to the ECU, and the ECU turns on the relay.
dave.a.cote
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Re: MS3 + MS3X + BMW M50

Post by dave.a.cote »

I'll give it a shot - I guess I'm mostly confused as to why this diode/transistor combo is necessary. Why doesn't the key turn on the relay?
hassmaschine
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Re: MS3 + MS3X + BMW M50

Post by hassmaschine »

dave.a.cote wrote:I'll give it a shot - I guess I'm mostly confused as to why this diode/transistor combo is necessary. Why doesn't the key turn on the relay?
because it keeps high current from going through the ignition switch. It's basically a copy of the circuit used in the factory ECU. the ECU has a constant 12v (high current from the battery), a switched 12v from the ingition switch (low current), and a connection to trip the main relay.

just do it, BMW did it that way for good reason. :D

I understand the confusion, I didn't get it either. Actually the original instructions made little sense to me, so I reverse engineered them to better understand exactly what it was doing. maybe I'll do a real diagram (the original diagram sucks) and some pics for better clarity.
hassmaschine
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Re: MS3 + MS3X + BMW M50

Post by hassmaschine »

oh, you're using an M50NV harness right? check the pins, they probably changed. When I'm done I want to go back and do a chart for the NV engine.
dave.a.cote
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Re: MS3 + MS3X + BMW M50

Post by dave.a.cote »

I think that part of the harness is the same between the NV and vanos setups.

http://forums.bimmerforums.com/forum/sh ... p?t=879273

I am still using pins 26, 27 and 56 to connect the components but I think that there is a bit of info missing - I will go off of your instructions.
hassmaschine
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Re: MS3 + MS3X + BMW M50

Post by hassmaschine »

if you beat me to it, let me know how it works. I'm sort of dead in the water until I get my harness.
dave.a.cote
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Re: MS3 + MS3X + BMW M50

Post by dave.a.cote »

It worked! Thanks for the help - now I have to figure out my sensor calibrations and timings ect. before I can try and start it.
hassmaschine
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Re: MS3 + MS3X + BMW M50

Post by hassmaschine »

nice! good to hear. I've got 3 setups to build that circuit for.
David. A
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Re: MS3 + MS3X + BMW M50

Post by David. A »

dave.a.cote wrote: I am using the ignition outputs A through F on the MS3X going to 6 330 ohm resistors and then to the left pin on 6 coil drivers sold by glens garage.

With MS3x there is no need to wire the 330 ohm resistors.

David
Car: BMW 318Ti 1995 1.8 M42 Engine.
Megasquirt 3.0 + MS3x board Code 1.3

4cyl Cop Ignition,crank+cam wheels based on vr sensors.
Ignition: full sequential
Fuel: full sequential
Bosch 3 wire pwm idle valve
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