Hi all,
I’m running an EMU Black V3 on a Porsche 718 Cayman engine (DNYA, 2.0 turbo, MA1.20), converted from direct injection to port injection. Ignition stays on the OEM Bosch single coils, part number 0 986 221 120 (also listed as Porsche 9A7 905 093 00 / BorgWarner-BERU ZSE225). These are smart coils with integrated IGBT driver, 4-pin connector (Coil-on-Plug).
I haven’t been able to find verified dwell time values anywhere — not in the Bosch catalog, not in previous threads here. Has anyone run these coils on an EMU Black (or similar standalone) and can share their dwell table (ms vs battery voltage)?
Also interested in:
Whether you’re running them as “Smart Coil” output type in V3
Any issues at high boost (target 1.2–1.5 bar) with misfires
Thanks in advance!
You can look at the coil primary dwell current ramp with a low amp clamp on an oscilloscope and measure the time to coil saturation if you can’t find this information elsewhere.
This is what Google AI has to say about these coils - FWIW. The dwell looks similar to other coils I have seen.
"For the BorgWarner-BERU ZSE225 ignition coils (commonly used in modern Porsche 9A2 engines like those in the 991.2, 992, and 718), the proper nominal coil dwell time at standard running voltage (14V) is 2.0 to 2.5 milliseconds (ms).
Recommended Dwell Voltage Curve
Because correct ignition coil dwell is highly dependent on system voltage, it should scale across a standard voltage table in an aftermarket ECU (such as MoTeC, Link, or Haltech):
| Battery Voltage |
Suggested Dwell Time |
Purpose / Condition |
| 10V |
4.0 – 5.0 ms |
Engine Cranking (Low Voltage Compensating) |
| 12V |
2.8 – 3.2 ms |
Low Battery / Charging System Strain |
| 14V |
2.0 – 2.5 ms |
Normal Engine Running (Optimal Operating Range) |
| 16V |
1.6 – 1.8 ms |
High Voltage System Control |
Core Safety Guidelines
- Do Not Over-Dwell: Avoid exceeding 3.5 ms at normal operating voltages. Modern VAG and Porsche smart coils have internal electronics that handle precise discharge cycles; pushing excessive dwell times translates directly into excess thermal heat rather than stronger spark energy. As noted by the HP Academy Tuning Guidelines, “If our dwell time is set too high, we’re physically going to put too much heat into the coil and it’s going to end up melting the coil.”.
- High-Boost Adjustments: If you are running high boost levels on a custom tune and experiencing spark blowout, try minimizing your spark plug gap first rather than heavily increasing the dwell time. Alternatively, custom engine maps sometimes use a manifold-pressure-based multiplier to scale the dwell up slightly under peak load, keeping it tightly controlled.
Thanks for taking the time to respond! I’m aware of the AI-generated dwell tables for this coil family — they do seem plausible and in line with similar Bosch smart coils. However, I was hoping for verified values from someone who has actually measured coil saturation on these specific coils (0 986 221 120) with an oscilloscope or has hands-on tuning experience with them on a standalone ECU. If anyone has real-world data, I’d really appreciate it!