Additional Enrichment

Some models use a standard thermo time switch and cold start valve to provide cold start enrichment. Other models use a combination of the following devices or systems to enrich the mixture.

During cold engine cranking, a signal from the starter relay is sent to the ECU to enrich the fuel mixture. A thermo timer controls enrichment cycle time after starting.

Fuel enrichment during warm-up is controlled by the DPR. When cold, the signal from the coolant temperature sensor allows more current to be supplied to the pressure regulator. This will provide greater fuel enrichment.