M142 and Ignitor Suggestion for BMW B38 Engine

[Senta]

Hi,

I'm currently working on a BMW B38B15A engine and I wish to control it with MoTeC M142 ECU. I do understand that MoTeC M142 does not come with a high amp ignitor so I'm thinking to get one for the engine. The problem is I have no clue which ignitor module I should look for.

The OEM ignition coil has 3 pins on it, the resistance measured at first and third pin is about 0.4~0.5 ohm. Nothing on first to second or third to second pin.

The possible BMW Part no is
12138678438 or 12138647463

Any advice and suggestions would be greatly appreciated!

Regards
Steven

[Stephen Dean]

From what I can find about those coils, and by them having a three wire connector, they have a built in ignitor, meaning that they do not need an external module.

[Senta]

Hi SDean,

Thanks for the informative reply.

In the M1 ECU hardware tech note, the max current of the low side ignition output is 3.5A(2A for RMS current). May I know what is the maximum ISDM (Source-Drain current pulsed) of the low side ignition output?

[AdamW]

If you are measuring 0.5ohm between two pins that would suggest they are non-amplified coils in my experience. With many BMW 3 pin non-amplified coils the third pin is the secondary (HV winding) ground. You could confirm this by measuring if there is resistance to the HT output post.

[Senta]

If you are measuring 0.5ohm between two pins that would suggest they are non-amplified coils in my experience. With many BMW 3 pin non-amplified coils the third pin is the secondary (HV winding) ground. You could confirm this by measuring if there is resistance to the HT output post.

Hi Adam,

I'm getting 20M ohm from 2nd pin (negative terminal from meter) to HT output post (positive terminal from meter). Nothing shows up when I switch the polarity of the meter terminal. I suspect there is a build-in diode in between this two-point.

[GE Race Tune]

Sounds a LOT like the BMW S1000RR coil

3 Pin,

1, Trigger
2, GND
3, B+

I am a big fan of the IGN4 module due to its size, price and ease of installation.. Had previously used a Bosch 4 channel ignitor, its bulky, takes more time to wire (I/O on both sides of it) and its not as sealed as the Deutsch connectors of the IGN4.. Plus the IGN4 is cheaper from Motec than what the 4 channel Bosch sells for