Applications Honda K20
Draft. Trigger offset has not been confirmed on a running Race Core install. Pins marked TBD are unknown — do not guess them. A wrong decoder or firing order can destroy the engine.
Honda K20 / K24
K-series. 12-1 crank (HONDA_K_CRANK_12_1), 4+1 cam, i-VTEC = VTEC rocker + intake VTC phaser. Coil-on-plug. DBW on later K24.
Recommended: F7 or V4. Four sequential, four COP, VTEC on a high-side or low-side (on/off), VTC on Highside 1 (PWM).
- Cylinders: 4
- Displacement: 1998 (K20) · 2354 (K24) cc
- Firing order: 1-3-4-2
- Orientation: Cylinder 1 timing-chain / gearbox end on a transverse Civic — confirm; Honda stamps the cam cover.
Variants
| Variant | Years | Trigger | Notes |
|---|---|---|---|
| K20A / K20A2 / K20Z | 2001–2011 | 12-1 crank + 4+1 cam | EP3, DC5, FN2. Cable on most. i-VTEC. |
| K24A / K24Z | 2003–2015 | 12-1 + cam, some DBW | CR-V / TSX / later Civic. More torque, same decoder family. |
Recommended pin assignment (Race Core F7)
| Pin | TunerStudio | Function |
|---|---|---|
| B10 | Digital 1 | Crank 12-1 Hall |
| B1 | Digital 2 | Cam 4+1 Hall |
| A3 | Lowside 1 | Injector cylinder 1 |
| A15 | Lowside 2 | Injector cylinder 2 |
| A4 | Lowside 3 | Injector cylinder 3 |
| A16 | Lowside 4 | Injector cylinder 4 |
| A35 | Ign 1 | Cyl 1 logic coil |
| A34 | Ign 2 | Cyl 2 logic coil |
| A22 | Ign 3 | Cyl 3 logic coil |
| A33 | Ign 4 | Cyl 4 logic coil |
| C20 | Analog Temp 3 | CLT |
| C30 | Analog Temp 2 | IAT |
| C13 | Analog Volt 1 | MAP 0–5 V |
| C24 | Analog Volt 2 | TPS 1 |
| C34 | Knock 1 | Knock bank 1 |
| A20 | Lowside 10 | Fuel-pump relay coil |
| A21 | Lowside 12 | Main-relay coil |
| A12 | Lowside 15 | Radiator-fan relay coil |
| A1 | Highside 2 | VTEC solenoid (on/off) |
| A2 | Highside 1 | VTC phaser (PWM) |
| B18 | Battery Sense | Ignition-switched 12 V (5 A fuse) |
| B23 | +12 V MR | Main-relay 12 V into ECU |
| A17 A18 A24 B14 B19 B20 | Power GND | Engine block → battery − |
Trigger
Honda K 12-1 crank, Hall, crank pulley. Cam 4+1. TunerStudio: HONDA_K_CRANK_12_1 and Honda K cam. Not a 12-tooth Toyota crank.
Crank
| 12-1 | Hall, Digital 1, 12 V, pull-up on. |
Cam
| 4+1 | Digital 2. Needed for VTC and sequential. |
TunerStudio
| Setting | Value |
|---|---|
| Trigger / wheel type | Honda K 12-1 + Honda K cam 4+1 |
| Use only rising edge | VR: typically yes on MAX992x. Hall: as logged. |
| Invert primary | No — swap VR wires first |
| Firing order | 1-3-4-2 |
Offset: Light on cylinder 1. Honda damper marks are on the pulley — confirm TDC with a piston stop once if the pulley has been swapped.
- A K24 trigger in a K20 bay is the same decoder. Displacement and VTEC enable RPM change.
Injection
High-Z, sequential four. ~240–310 cc OEM.
| Fuel | Return on most K20. Keep it. |
Ignition
COP logic Ign 1–4. Dwell 2.0–2.5 ms.
Idle
Cable + 2-wire IAC on EP3/DC5. DBW on some K24. Identify the throttle.
First start
- Load the matching variant configuration in TunerStudio before the harness is live — injectors and coils stay disconnected until the decoder is confirmed.
- Fuel pump fuse out. Coils unplugged or spark outputs disabled. Crank. Open Diagnostics → composite / high-speed logger.
- Confirm crank teeth are even, the missing-tooth (or named pattern) is a single clean gap, and cam is one pulse per two crank revolutions for sequential four-stroke.
- RPM during cranking should sit in the 150–350 rpm band. 0 rpm or 12,000 rpm means the decoder is lost — polarity or wheel type, not offset.
- Lock timing to a fixed 10° (idle control off). Timing light on cylinder 1. Change trigger offset until the damper agrees with 10°.
- Recheck at ~3,000 rpm. If timing walks with RPM, it is VR polarity, a delayed Hall, or the wrong decoder — not offset.
- Enable spark. Confirm a healthy burn (timing light or plug colour) with fuel still disabled.
- Enable fuel. Prime, then crank. Catch the first idle on a rich-safe VE, then lean toward stoich at idle.
- Only then enable closed-loop idle, VVT, boost and traction. A base map is a starting point, not a dyno tune.
A base map is a starting point, not a dyno tune.