What is a cold start injector on a 1986 Honda CRX?

Answer 1

The cold start injector does what the name implies. When you first turn the key to start (on a cold engine) the CSI gives the engine a richer mixture by injecting fuel into the intake manifold while the starter is engaged so it starts faster/easier. How long the cold start injector runs depends on the temperature. (Usually only a few seconds). There isn't a cold-start injector on your car. The cold-start injector, aka the "fifth injector," is a relic of the Bosch K-Jetronic fuel injection system. This was designed in the 1960s and is essentially mechanical. On the K-Jetronic, when the Cylinder Head Temperature sensor detected the engine was below a certain operating temp, it would inject fuel into the throttle body. Think of it as a fancy choke. Cold-start injectors have one huge problem in today's emissions-paranoid climate: all that extra fuel generates extra pollution. That will not do. Honda uses a cold-advance solenoid valve in 1986 cars. There is a cable connecting it to the FI computer, and a vacuum hose connecting it to the distributor. (For all you guys who ever wondered why there are TWO hoses going into the vacuum advance on a Honda distributor when most cars only have one...well, this is why.) When the engine is below operating temperature, the cold-advance solenoid draws vacuum on the distributor, which advances the timing and makes the engine run faster without all the smog a cold-start injector would cause.