G4x COP conversion not starting

[UnknownMiscreant]

Hi,

I'm hoping someone might be able to spot something I've missed on this one.

Over the weekend I tried to do a COP conversion on my Mini R53 with a G4x plugin. Headline it refused to start.

I used BMW B58 coils (12v, GND and switched primary) which I setup on Ignition 1-4. Ign3 and 4 had external IGBTs for igniters exactly the same as the internal igniters on the v1.3 MiniLink board, STGB10NB40LZT4 IGBTs with 680r and 10K resistors on the gate (680r ECU to gate and 10k gate to GND.) I grounded the coils to the cylinder head and the external igniters to the engine loom/ECU ground point next to the fuse box.

For switched 12v I depinned the coil pack wire from the engine loom connector on the fusebox and stuck a new crimp in. I also depinned the ECU connector for the coil wiring.

All coils produced spark and were assigned to the correct cylinders. Ignition tests all produced spark on the correct cylinders.

It was definitely getting fuel. Very easy to smell on the plugs when I pulled them.

I tried trigger scope and that looked correct. No trigger errors were logged until it stopped cranking.

I put it back to the OE wasted spark coil and it started right up as per normal.

I wired everything up on a spare cylinder head on my desk and everything worked as I'd expect. Strong spark and the coils were hitting current limit on my bench supply at the ECU calculated 4.4ms dwell @10.8V while cranking. Wiring is 18AWG and about 54mOhm total primary wiring resistance (4wire kelvin measurement) so around 0.43v wiring loss at 8A. 

Map and a brief log attached. Dwell settings came from calculations someone did off a B58 ECU (actually for running the coils on an N54)

Trigger setup is all OEM. Theres no timing marks on the engine so I'm running the provided trigger calibrations.

Thanks

B58 COP.pclx B58 not startingPC Datalog - 2022-08-20 9;32;21 pm.llgx

[Confused]

If it was previously wasted spark, you might need to change your Trigger Offset by 360 degrees - you may now be trying to fire on the exhaust stroke.

[UnknownMiscreant]

2 minutes ago, Confused said:

If it was previously wasted spark, you might need to change your Trigger Offset by 360 degrees - you may now be trying to fire on the exhaust stroke.

That is basically the only thing left I can think of.

I'll throw COP back on it and try that when I next have some time.

[Adamw]

Yeah everything looks ok ecu wise and your wiring sounds good.  I would say most likely trigger offset is 360 out.  

[UnknownMiscreant]

10 hours ago, Adamw said:

Yeah everything looks ok ecu wise and your wiring sounds good.  I would say most likely trigger offset is 360 out.  

20 hours ago, Confused said:

If it was previously wasted spark, you might need to change your Trigger Offset by 360 degrees - you may now be trying to fire on the exhaust stroke.

Thanks guys. Sadly no luck still.

I put COP back on it this evening and tried 94 (link provided), 266 and -266 timing offsets. Best I got was backfiring while cranking.

Ignition tests all produced a good spark on the correct cylinders.

Has anyone got any further ideas? All good if not I'll stick with the OE wasted spark setup.

[Adamw]

If it runs on wasted spark with the offset at 94, then it can only be 94 or -266.  So when you say spark on the correct cylinders, do you mean ign test 1 gives a spark on cyl 1, ign 2 test gives a spark on cyl 2 etc?  

Do you have the coils pined as below?

[UnknownMiscreant]

4 minutes ago, Adamw said:

If it runs on wasted spark with the offset at 94, then it can only be 94 or -266.  So when you say spark on the correct cylinders, do you mean ign test 1 gives a spark on cyl 1, ign 2 test gives a spark on cyl 2 etc?  

Do you have the coils pined as below?

Correct. Ign test 1 gives spark on 1 etc. 

Is that diagram looking at the connector or the coil?

I went off the BMW wiring diagrams, with pin 1 as 12v, pin 2 GND, pin3 IGBT.

[Adamw]

Yes that is looking into the connection on the coil.  I suspect 3 wire coils would work either way around anyhow since the 3rd pin probably means the secondary ground is not connected to the primary 12V as it is in most 2 wire coils.  But if yours are wired different to this it wouldnt hurt to swap as a test.  That pic is out of the Facet catalog so I have good confidence in it.  

[UnknownMiscreant]

35 minutes ago, Adamw said:

Yes that is looking into the connection on the coil.  I suspect 3 wire coils would work either way around anyhow since the 3rd pin probably means the secondary ground is not connected to the primary 12V as it is in most 2 wire coils.  But if yours are wired different to this it wouldnt hurt to swap as a test.  That pic is out of the Facet catalog so I have good confidence in it.  

Okay, so I have + and - swapped then. I'll switch and give it a try.

35 minutes ago, Adamw said:

Yes that is looking into the connection on the coil.  I suspect 3 wire coils would work either way around anyhow since the 3rd pin probably means the secondary ground is not connected to the primary 12V as it is in most 2 wire coils.  But if yours are wired different to this it wouldnt hurt to swap as a test.  That pic is out of the Facet catalog so I have good confidence in it.  

Still no luck. I'd say 94 deg timing offset is correct. -266 results in backfiring while cranking.

It doesn't even try to run with the COP coils with wasted spark selected in PClink. Bit of a dumb test, but I have had it running on 2 cylinders on the stock EMS2k ECU back when I managed to break an HT lead. It idled pretty well but sputtered and just about stalled out as soon as you put any throttle on

[Adamw]

11 hours ago, UnknownMiscreant said:

It doesn't even try to run with the COP coils with wasted spark selected in PClink. Bit of a dumb test, but I have had it running on 2 cylinders on the stock EMS2k ECU back when I managed to break an HT lead. It idled pretty well but sputtered and just about stalled out as soon as you put any throttle on

Yeah I would have expected it to nearly run like that.  It sounds like it has a very weak spark or something.  I have seen similar for example dumb coils without an ignitor wired direct to the ecu low current output.  The coils will spark fine with ignition test when outside of the cyl, but when inside the combustion chamber under cyl pressure they no longer spark.  Have you tried a timing light on on plug when cranking?

 

[UnknownMiscreant]

6 hours ago, Adamw said:

Yeah I would have expected it to nearly run like that.  It sounds like it has a very weak spark or something.  I have seen similar for example dumb coils without an ignitor wired direct to the ecu low current output.  The coils will spark fine with ignition test when outside of the cyl, but when inside the combustion chamber under cyl pressure they no longer spark.  Have you tried a timing light on on plug when cranking?

Thanks, I certainly think that is a correct assessment. I did try crank the dwell to 8ms and noticed no change. I do have a timing light but its a jank affair I made a while ago for playing with a dizzy on an old V8. Although theres no timing marks on the R53 which makes things a little tricky. I could throw a scope on the wires between the coils and IGBTs. My scope is sensitive enough to get around 0.2-0.5A resolution off a 20-30mOhm cable.

I have some eldor R8 coils on another car I'll have a go with this weekend. Any recommendations for hooking those up to ignition drives 1&2 with the inbuilt IGBTs? External pullup and rising edge spark is probably the easiest route out but that'll shoot me in the foot for 3&4. I initially went with a dumb coil as it makes life a little easier given the inbuilt igniters. Could always run COP with wasted spark as a test given the low current needed to switch the R8 coil igniters. 

[UnknownMiscreant]

6 hours ago, UnknownMiscreant said:

Any recommendations for hooking those up to ignition drives 1&2 with the inbuilt IGBTs? External pullup and rising edge spark is probably the easiest route out but that'll shoot me in the foot for 3&4. I initially went with a dumb coil as it makes life a little easier given the inbuilt igniters. Could always run COP with wasted spark as a test given the low current needed to switch the R8 coil igniters. 

P channel FET and a couple of pullups do the trick.

[UnknownMiscreant]

Figured I'd update this having got to the bottom of things after spending a day playing with R8 coils. I'm running a p-channel FET on Ign1&2 to invert the outputs for the built in igniters.

The problem stemmed from incorrect pin assignment on the MiniLink v1.3 board. Ign1 and 2 are swapped. Ign1 runs cylinders 2&3, ign2: 1&4. This got compensated for in the timing calibration which meant timing went out the window running direct spark.

[Adamw]

You originally said this though?:

On 8/22/2022 at 11:02 PM, UnknownMiscreant said:

All coils produced spark and were assigned to the correct cylinders. Ignition tests all produced spark on the correct cylinders.

 

[UnknownMiscreant]

47 minutes ago, Adamw said:

You originally said this though?:

It is still true. 

Ignition test with both my direct spark setups always produced spark on the correct cylinders. Up until now I never tested the OE coil or wiring as it ran perfectly so I assumed everything was fine.

I tried running the R8 coils in wasted spark mode. Figured it should be Ign1 controlling coils 1&4 and Ign2 controlling 2&3. When that too refused to run I took more of a look at the OE wiring, and found pins 3&4 on the MiniLink ECU (ign drives 1 and 2) are swapped. When I swapped the R8 coils to trigger the same as the OE coil it started right up.

It runs direct spark perfectly with a timing offset of -86deg. 180deg behind the link provided offset of 94deg.

Thanks for your help on this one.

[Adamw]

Ah ok, I get you now, offset was off by 180, but we only suggested trying +/-360 before.  

[UnknownMiscreant]

4 hours ago, Adamw said:

Ah ok, I get you now, offset was off by 180, but we only suggested trying +/-360 before.  

Ya. 360deg seemed alot more likely given the symptoms.

Might be kind to stick something in the known issues for MiniLink. The wiring diagram for OE coils is below (wire colors are abbreviated German.) This matched the OE wiring on my car.

I've stuck the MiniLink pinout below too.