What the "ZZ coil" is
We'll call it the ZZ coil for short. It's an inductive coil with an igniter built into the body, and it sits right on top of the spark plug. Toyota used this design across a lot of engines from the late 1990s onward. It's best known from the Yaris 1NZ and the Corolla 1ZZ and 2ZZ, which is why it's cheap and easy to find in wrecking yards. Most Toyotas from that era used the same basic coil with different plug angles and tube lengths, so check the tube length suits your head before you buy.
Haltech doesn't sell this coil. But because the igniter is inside, a Haltech ECU's ignition outputs can trigger it without a separate ignition module.
Haltech Elite settings
| Setting | Value | Why |
|---|---|---|
| Ignition Mode | Direct Fire | One coil per cylinder, each fired on its own |
| Ignition Edge | Falling | The coil fires as the trigger signal drops |
| Ignition Dwell Mode | Constant Charge | Charge time is set by the dwell table, not a duty percentage |
Getting the edge wrong is the classic mistake with any smart coil: the coil charges when it should be resting, gets hot, and the spark lands at the wrong time. Double-check it before cranking. For dwell, start from a conservative table and confirm the coils stay cool. If you'd like our suggested ZZ dwell table, ask us. The dwell time article explains how dwell tables work.
Wiring and power supply
Each coil needs switched 12V, a ground and its own ignition output from the ECU. Pay attention to the power feed. A ZZ coil can pull up to about 8A. At high RPM and high power, that adds up quickly, and a single conventional 30A relay feeding every coil may not keep up. It isn't common, but on big builds it can be worth giving each pair of coils its own fuse and relay.
Wire size matters too. Thin supply wiring drops voltage under load, and a coil that's short on voltage makes a weaker spark, which often shows up first as a high-RPM misfire under boost.
If a ZZ coil setup misfires only at high load and RPM, measure coil supply voltage while it happens before you blame the coils. See how relays work for sizing the supply.
Comparing options? See the IGN-1A and LS2 coil guides, or internal igniter or not.
