Honda LEAD 110 2009 Service Manual page 41

TECHNICAL FEATURES
FUEL ENRICHMENT FOR COLD ENGINE
ENGINE RUNNING CONDITION WHEN IT IS STILL COLD:
Fuel does not vaporize well in a cold engine and air-fuel ratio becomes very lean, causing unstable idle.
COLD ENGINE WITH CARBURETOR (WITH SE THERMAL VALVE):
When engine is cold, proper air/fuel ratio and fast idle speed are maintained by means of SE thermal valve, which intro-
duces additional fuel/air from starter port, supplementing the fuel from idle port.
FUEL CONTROL CIRCUIT
START UP CIRCUIT
IDLE CIRCUIT
COLD ENGINE WITH PGM-FI:
When engine is cold, ECM regulates the amount of fuel by lengthening the opening duration of injector, in accordance with output voltage
from ECT sensor, depending on engine condition, while controlling IACV which introduces additional air in order to maintain fast idle
speed.
2-4
IDLE PORT
STARTER PORT
BASIC DISCHARGE
DURATION
CORRECTED
(ADDED)
DISCHARGE
DURATION
FOR COLD
ENGINE
SE THERMAL VALVE
CARBURETOR
INJECTOR
PGM-FI THROTTLE BODY
IACV