Link G4X BMW - on BMW M42 4 cylinder

[BMW-Bob]

Hello All,

I am new to Link ECUs.  I've tuned several BMW factory ECUs before switching to Link.

I have the Link G4X BMW, connected to a factory M50 harness (6 cylinder), but running the harness and a M42 (4 cylinder).  I have 2 less injectors, and 2 less ignition coils.  I am using the base map for the 6 cylinder with changes for 4 cylinder firing order.  I have the all of the calibrations done, and the triggers calibrated.  I cannot get this to start.  It will cough and misfire, but not enough power to run on it's own.

1 of the areas I think I might need to go back and check is the trigger calibration.  I have the offset set to 114° and verified it with a timing light.  The M42 cam trigger is different from the M50.  I know from setting the cam timing, the cam trigger pin will pass the sensor at ~30° after TDC2 with the firing order of 1-3-4-2, thus after the trigger 2 is seen, the firing order starts at the beginning TDC1.  I've tried 360° offset also with little change.  Same cough and misfire.

Planning on checking the ignition wires and coils, and I will look at the trigger scope and other inputs tonight to verify everything.  Looking for you replies.  I will have the file and logs coming.

thanks

bobk

[Adamw]

If you are sure the timing light shows the correct timing with the offset at 114 then either that or 360 earlier at -246 is correct. 

However, I just done a quick search for "M42" on the forum and the first map from a running M42 I found has the offset at -114, so I would be suspicious your 114 is not correct. 

 

Would need to see the trigger scope to confirm what sync mode you need.  Does your engine have dumb coils? 

[BMW-Bob]

Hello Adamw,

thank you for the reply.  -114° is where I have the offset.  Sorry typo, I forgot the '-' negative sign.

I did find the problem last night.  When I was testing the ignition, I found the #2, 3, and 4 were not wired correctly.  Lesson learned, do not trust factory manuals!    BMW M50 have direct fire coil on plug.  Pre-1994 BMW M42 used the same coils, but the coils were remote mounted and had plug wires.  1994+ M42 changed to a 4in1 integrate coil pack, part number 12131247281, and used plug wires.  These are all 'dumb' coils.  I grafted the M42 4in1 coil harness into the M50 engine harness.  That's were I made the mistake.

I corrected the wiring mistake.  Now the ignition tests show the correct plugs firing.  Engine still coughed and missed.  I changed the ignition offset from -114° to 246° and it fired right up!

Had to do some BIG changes in the master fuel.  It was VERY rich.  I'm running bigger injectors.  Need to do some work on the idle control and it won't rev past ~2500 it goes lean... but it is running and I can start tuning.

I'm excited and eager to learn and tune with LINK.  Hoping for big gains, more control, and a better running engine!