Injected Twin Cam High Temperature Idle
Fuel injected Twin Cam engines use a four phase heat management system to reduce engine temperature under extreme conditions. A rider with a very hot engine may notice the affects of this four phase heat management system and incorrectly assume an idle problem exists.
Phase 1: When the engine temperature sensor signals that the cylinder head has reached approximately 266° F (130° C) the ECM will gradually reduce engine idle speed until the engine temperature drops or the engine reaches 900 RPM.
Phase 2: If engine temperature reaches 293° F (145° C), the ECM will gradually reduce engine idle speed until the engine temperature drops or the engine reaches 800 RPM.
Phase 3: If the engine temperature reaches 322° F (161° C), the ECM richens the air/fuel ratio to provide additional cooling and advances the spark timing 10°.
Phase 4: If the engine temperature reaches 331° F (166° C), fuel injector pulses (2 of 8) are randomly interrupted. The air drawn in and expelled helps cool the engine further. Since there is no combustion it would be perceived as a misfire. This fourth stage will only happen when the motorcycle is stationary.
If necessary, engine idle speed will be increased during all Phases to maintain proper battery voltage.