Honda K20Z4 - Cranking issue

Hello everybody,

Just starting to run a HONDA K20 Z4 engine with EMUBLACK V3.

Struggling to start on cranking … Scope seems odd, but once the engine is fired, everything run well.

I am new to ECUMASTER, and I don’t really understand the cranking scope (if anyone has a written explanation).

Here the map.

BECT_EMUB_HONDA_K20_Z4_SP98_20260203_V49.emub3 (65.4 KB)

Here is the latest scope, and data of the engine cranking.

scope_202623_1939.emubscp31.emubscp3 (624 Bytes)

20260203_1958.emublog32.emublog3 (1.7 MB)

20260203_1917.emublog3 (588.0 KB)

Also the log from the old start when engine is idling (I was working on injection time)first_real_start_20260125.emublog3 (6.9 MB)

problem_Ign_change_from20to6.emublog3 (2.5 MB)

(Already read that a K20 is “hard” to start, but didn’t found a proper solution for my case).

And I did not tried on V2 software, is it a solution ?

Thank you all ! :smile:

UPDATE

If someone has already been struggling with cranking RPM signal loss …

Can’t find, wiring’s fine. 12 teeth + 1 / TDC Angle ok and first tooth ok also.

Kinda lost :shaking_face:

I think you have several issues here and your starting issues looks to be related to fuel because if we judge by lambda its lean during cranking and the engine needs way more fuel especialy on cold.

  1. Fuel table, on Idle your VE should be around 40-50% assuming the engine data was filled in correctly including the fuel injector size and dead times.
  2. The Injector phase start from a 380 degree value and then tune from there.
  3. If the above will not help enough start adding cranking fuel for the clt temp you are in.

Not sure but did you synchronized your mechanical timing with EMU trigger angle ?

100 thanks for your answer, and you are right, my starting issue is more related to fueling.

But, my main concern is about cranking trigger resolution. I checked the trigger with ign angle lock during the first start (when it was actually starting).

I started with 12+1 teeth, Teeth num 10 and 40° angle. Then, after check and calculation, it was teeth num 7 and 102° angle.

Agree that the cranking fueling is not perfect. Inj dead time took from wizard (+/- correct).

What I don’t understand is why the RPM goes from 600 (ready to idle) to 0 and so on the sync is lost … Wiring seems fine.
Not sure about the trigger setup (Pull Up, filter etc), but tried multiple mix

“What I don’t understand is why the RPM goes from 600 (ready to idle) to 0 and so on the sync is lost … Wiring seems fine.”

  • Hall sensors require a pull up, try different pull up values
  • The 102 trigger angle looks suspicious because in the ECUmaster requirements for this value it states that it should be round 60 +/- 10 degree
1 Like

When the RPM drops to 0, you can sometimes see the “Unexpected missing tooth” error.

This error can be generated by any incorrect signal on the crank or cam.
It could be missing, or there may be an additional edge on the crank or cam generated by noise.

Is this OEM trigger setup, or aftermarket?
Are both sensors 3-pin Hall effect?

Try setting the maximum filter for both crank and cam.

1 Like

Thank you for your explanation !

trigger wheel is OEM from K20, so 12+1

Hall effect for the 3 sensors (crk, cam in & cam ex). Shielded to écu power gnd. 12V supply

ok Will try max filter. Do you recommend using internal PullUp 1K ? Also read that using rising might help for resolution : true ?

Hall sensors require pull up resistor.
Pull up 1k or 820R is ok.

I don’t know what you mean by resolution.
But changing the edge can help with correct decoding.

Remember that any change in the trigger can affect the actual ignition angle, so when you finalize the trigger settings, you should perform a final check with a timing light.

1 Like

Lot better with high filter !!! And also the rising edge help before going with high filter level.

Will see tomorrow with higher cranking fuel values because engine likes the amount of brake cleaner we put before DBW !!!

Keep you informed. :crossed_fingers:

So, thanks to Marek & Alex, the cranking losing has been resolved by the high level filter + rising edge.

Honda K20 trigger is now correctly mapped (first tooth & first trigger angle).
The biggest problem was a wrong wheel triggering (I suppose).

Now that the trigger has been checked with stroboscopic, it starts good.

But still having (sometimes) sync lost on the trigger status signal on log
Here attached.

20260207_1731.emublog3 (3.9 MB)

BECT_EMUB_HONDA_K20_Z4_SP98_20260207_V86.emub3 (194.7 KB)

Will continue to run, and perfect also the cranking & starting fueling and so on.