F20C (AP1) Engine
Information on the Honda F20C engine as found in the AP1 S2000
General Information
| Cylinders | 4 |
| Displacement | F20C 1997 cc / 121.9 ci F22C1 2157cc / 131.6 ci |
| Firing Order | 1,3,4,2 |
Model Variants
There are a number of variants of the F20C engine.
JDM F20C
11.7:1 comp, 9000rpm limit
USDM UEDM and AUDM F20C
AUDM and EUDM All year models
Compression dropped to 11.0:1, MY06-on adds DBW
F22C1
USDM MY04-on
JDM MY06-on
2157cc displacement through longer stroke, 11.1:1 comp, 8200rpm limit, MY06-on adds DBW.
Common Models
Found only in the S2000
Sensor Information
Crank/Cam Sensor
This engines uses a Crank Position Sensor and a Cam Position Sensor. The crank trigger wheel has 12x equally spaced teeth, and the cam trigger has 3x teeth spaced 90-deg apart (effectively a 4-1) on teh back of both cams. Reluctor sensors are used for all.
Crank Trigger Wheel
Cam Trigger
Trigger Configuration
There are reports of more than one TDF Offset Angle value that aligns the ignition timing. On the unmodified test car we had at Haltech this value was correct at 709 and this is shown in the image below. Reports that a value of 33 from a Euro car and also 20 is required to align some vehicles.
A correction table is required to keep the ignition timing correct with different RPM.
Crank Sensor
A Hall Reluctor crank position sensor is used. This is located near the timing cover.
Reluctor Wiring
| Pin | Description | Haltech Connection (Trigger 4-core) |
| 1 | Reluctor - | Trigger - Green |
| 2 | Reluctor + | Trigger + Yellow |
3 | --- | --- |
Cam Sensor
Reluctor cam sensors are used. These are located on the back of the cylinder head. Either one can be used however it will change the TDC Offset
Sensor 1
| Pin | Description | Haltech Connection (Home 4-core) |
| 1 Red | Reluctor - | Green |
| 2 Green | Reluctor + | Yellow |
Sensor 2
| Pin | Description | Haltech Connection (Home 4-core) |
| 1 Black | Reluctor - | Green |
| 2 Yellow | Reluctor + | Yellow |
Ignition System
The KF20C engine uses Direct Fire with an ignition coil per spark plug. The coils have an internal igniter module and are wired directly to the ECU. Settings are Constant Charge with a Falling edge. Selecting incorrect settings will damage the coil and possibly the ECU.
| Pin | Description | Haltech Connection |
| 1 | ECU Signal | Ignition Output |
| 2 | Ground to Cylinder Head | --- |
| 3 | 12V+ Switched | --- |
Dwell
DBW Throttle System
From 2006 this engine uses a single Drive By Wire throttle body. The throttle is controlled by a separate module and not directly from the ECU. The Haltech Elite 1500 or 2500 can directly read from the APP and control the throttle body.
DBW Throttle Wiring
Position Sensors
| Pin | Description | Haltech Connection |
| 1 (Red/Black) | TPS1 | AVI-2 (Orange/Black) |
| 2 (Blue) | 5V+ | 5V+ (Orange) |
| 3 (Red) | TPS2 | AVI-3 (Orange/Red) |
| 4 (Green) | Signal Ground | Signal Ground (Black/White) |
Drive Motor
| Pin | Description | Haltech Connection |
| 5 (White Blue) | Motor1 | DBW1 (Brown/Black) |
| 6 (White/Black) | Motor2 | DBW2 (Brown/Red) |
DBW Accelerator Pedal Position Sensors Connection
| Pin | Description | Haltech Connection |
| 1 (Yellow/Blue) | 5V+ | 5V+ Orange |
| 2 (Green) | Signal Ground | Signal Ground (Black/White) |
| 3 (Red/Yellow) | APP Signal 2 | AVI-4 (Orange/Yellow) |
| 4 (Red/Blue) | APP Signal 1 | AVI-5 (Orange/Green) |
| 5 (Yellow/Red) | 5V+ | 5V+ (Orange) |
| 6 (Green/White) | Signal Ground | Signal Ground (Black/White) |
Throttle Position Sensor
This engine uses a cable operated throttle body with a position sensor.
| Pin | Description | Haltech Wiring |
| 1 - Green/Yellow | Ground | Signal Ground (Black/White) |
| 2 - Red/Black | Signal | Spare AVI (AVI-10 White) |
| 3 - Yellow/Blue | 5V Power | 5V (Orange) |
MAP Sensor
This vehicle comes with a MAP sensor. This is located on the throttle body.
| Pin | Description | Haltech Connection |
| 1 (Green/White) | Ground | Signal Ground (Black/White) |
| 2 (Green/Red) | Signal | Spare AVI (AVI-9 Yellow) |
| 3 (Yellow/Red) | 5V | 5V Orange |
Calibration Data
For boosted applications over 70kpa it is possible to use the internal MAP sensor that comes with your ECU. For much higher boost levels an external MAP sensor should be used instead, connected to a spare AVI.
Variable Cams (VTEC)
The F20C engine uses a switched on/off variable lift system (VTEC).
Cam Control Switched
The Cam Control Switched function is used for the VTEC system. It requires only an output that has a high side drive capability. For the Elite ECU range a Stepper Output should be used for this purpose.
Idle Valve
This engine uses a 3-pin (Bypass Air Control) Valve which is duty controlled by the ECU via 1x output. Even though it has 3x wires it should be configured as a 2-wire BAC.
| Pin | Function | Haltech Connection |
| 1 Black | Ground | |
| 2 Yellow/Black | 12V+ Switched Power | 12V+ Switched |
| 3 Black/Red | ECU Duty Signal | Spare Output |
Coolant Temperature
Wiring is not polarity sensitive
| Pin | Haltech Connection |
| 1 | Any Spare AVI* |
| 2 | Signal Ground |
An AVI with a selectable Pullup should be used. If not and external 1k pullup to 5V should be connected.
Air Temp
Wiring is not polarity sensitive.
| Pin | Haltech Connection |
| 1 | Any Spare AVI* |
| 2 | Signal Ground |
An AVI with a selectable Pullup should be used. If not and external 1k pullup to 5V should be connected.
Knock Sensor
The F20C has an older style resonant knock sensor. They are prone to failure both internally, and externally where the plastic green body separates from the metal base. The sensor can be used however they become less reliable in operation the more the engine is modified. It is advised to replace the sensor with a donut style non-resonant sensor.
| Pin | Haltech Connection |
| 1 | Knock Signal |
| 2 | Signal Ground |
O2 Sensors
The F20C comes with Narrow Band sensors.
Adding a Haltech Single-Channel Wideband WB1 Kit (highly recommended)
For correct operation a Haltech WB1 kit is highly recommended for this application, with the provided 4.9 sensors replacing the pre-cat sensors. Sensors use a 22mm socket or spanner to remove and replace.
Vehicle Speed Sensor
This engine uses a Hall Effect Vehicle Speed Sensor.
Hall Effect Speed Sensor
| Pin | Description | Haltech Connection |
| 1 Yellow/Blue | 5V | 5V (Orange) |
| 2 Blue/White | Signal | Spare SPI |
| 3 Brown/Yellow | Ground | Signal Ground (Black/White) |
Injector Data
Flow
The injector flow rate is measured with the injectors held wide open at 100% duty. For fuel systems with a fixed regulator pressure (often returnless systems) that is not referenced to manifold pressure the flow needs to be mapped over Manifold Pressure for accurate tuning.
Injector Flow: 380 cc/min
Dead Time
When an injector is commanded to open for a certain amount of time, the dead time is the amount of time the injector is not actually open during this period. It covers the time to energise the solenoid and begin to open and the time to close as well. There are also transient periods during which the injector is opening and closing where fuel flow is not at full capacity so this lost peak flow period is also taken into account.
OEM ECU Information
Location
ECU Pinout
Base Maps
Base maps have been created for use with the Haltech Elite Adapter Harnesses. Platinum Pro - Maps come with the ECU Manager Software.
Where applicable those maps are attached below.
To use these maps they should be IMPORTED into your ECU. Follow the IMPORTING A BASE MAP guide.
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