This guide provides detailed instructions for B-series engine swaps into Honda Civics and Integras, focusing on the crucial Crank Fluctuation Sensor (CKF) and its implications for OBD1/OBD2 compatibility. We’ll cover engine installation, wiring modifications, and ECU options, specifically addressing the CKF bypass for OBD1 engines in OBD2 cars.
Understanding the CKF Sensor and OBD Compatibility
The CKF sensor, located on the oil pump of USDM OBD2 B-series engines, is critical for engine timing and is monitored by the ECU. OBD1 engines lack this sensor, creating a compatibility issue when swapping an OBD1 engine into an OBD2 chassis. This guide will explain how to overcome this challenge.
Engine Swap Procedures: Civic and Integra
96-98 Civic
- Engine Installation: Ensure correct mounts, linkage, and axles for your specific B-series engine (B16, B18, B20 VTEC). Refer to detailed guides for specific engine and chassis combinations to ensure proper fitment. Using 99-00 Si or JDM EK4/9 engine brackets is recommended for optimal positioning.
- Wiring:
- Reusing Your Existing Harness: You can reuse your existing engine wiring harness (EWH) or a 96-98 EX 5-speed EWH. Modify the harness for VTEC, knock sensor (KS), and Idle Air Control Valve (IACV) if using a non-VTEC harness with a VTEC engine. Diagrams for these modifications can be found online.
- Distributor, Injectors, Alternator, and IAT: Use OBD2 components for plug-and-play compatibility or modify your harness to accept OBD1 parts. Detailed guides and diagrams are available online.
- CKF Bypass: Implement the CKF bypass trick if using a USDM OBD2 ECU with an OBD1 engine. This allows you to avoid costly oil pump upgrades.
99-00 Civic
- Engine Installation: Information for the 96-98 Civic largely applies.
- Wiring: Similar to the 96-98 Civic, but may require changing the distributor plug to a 99-00 Si or 96-98 Civic type. The IACV modification is also necessary for OBD1 engines. Using a 99-00 Si EWH simplifies the process but requires manual wiring for the secondary O2 sensor.
96-01 Integra
- Engine Installation: Reuse existing mounts, brackets, axles, and linkage.
- Wiring: Reuse your existing EWH, following the guidelines for the corresponding Civic year (96-99 Integra follows 96-98 Civic wiring, 00-01 Integra follows 99-00 Civic wiring). Alternatively, use an OBD1 VTEC EWH from a 94-95 Integra GSR, 92-95 Civic Si/EX, or 93-95 DelSol VTEC, ensuring VTPS, VTS, and KS are wired.
ECU Options for all Swaps
- JDM OBD2 ECU: Easiest installation, but has a speed limiter and won’t pass US emissions tests. Does not require a VTPS.
- OBD1 ECU: Requires a conversion harness and VTPS wiring. Offers greater tuning flexibility but won’t pass emissions.
- USDM OBD2 ECU: Allows for emissions compliance with the CKF bypass. Requires wiring in the secondary O2 sensor. Specific ECU choices depend on the chassis and desired features.
Example of modifying OBD2 injector clips to fit OBD1 injectors.
CKF Bypass: A Critical Step for OBD1 Engines in OBD2 Cars.
The CKF bypass trick is crucial for using an OBD1 engine with a USDM OBD2 ECU. It simulates the CKF signal, allowing the engine to run correctly and potentially pass emissions tests. Detailed instructions for this modification are available online.
Comparison of OBD2a and OBD2b engine harnesses highlighting differences.
Conclusion
Swapping a B-series engine into a Honda Civic or Integra requires careful consideration of wiring and ECU compatibility, especially concerning the CKF sensor. By understanding the differences between OBD1 and OBD2 systems and implementing the correct modifications, including the CKF bypass, you can successfully complete your swap and enjoy the performance of a B-series engine. Remember to consult detailed wiring diagrams and guides for your specific application to ensure a safe and reliable conversion. Always verify local emissions regulations before modifying your vehicle.
