Injector Timing And Duration; Ignition Timing Control; Knock Sensor; Manifold Absolute Pressure (Map) Sensor - Honda S2000 Service Manual

Iniector Timing and Duration
The ECM contains the memory for basic discharge
duration at various engine speeds and manifold
pressures. The basic discharge duration, after being
read oul from the memory, is further modified by
signals sent from various sensors to obtain the final
discharge duration.
By monitoring long term fueltrim, the ECM detects long
term malfunctions in the fuel system, and will set a DTC
if the malfunction occurs during two consecutive trips.
lgnition Timing Control
T h e E C M c o n t a i n s t h e m e m o r y f o r b a s i c i g n i t i o n t i m i n g
at various engine speeds and manifold air flow rates. lt
also adjusts the timing according to engine coolant
remperarure.
Knock Sensor
The knock control system adjusts the ignition timing to
m i n i m i z e k n o c k .
PIEZO CERAMIC
OIAPHRAGM
TERMINAL
Manitold Absolute Pressure IMAPI Senso]
The MAP sensor converts manifold absolute pressure
i n t o e l e c t r i c a l s i o n a l s t o t h e E C M .
SENSOR UNIT
Primary and Secondary Heated Oxygen Sensors
{HO2Sl
The heated oxygen sensors detect the oxygen content
in the exhaust gas, then sends a signal to the ECM
which varies the duration of injeclion accordingly. To
stabilize its output, the sensors have an internal heater.
The primary sensor is installed in the exhaust pipe. The
secondary sensor is installed in the TWC.
HEATER
By controlling the airlfuel ratio with sensors, the
deterioration of the primary sensor can be evaluated by
its feedback period. When the feedback period exceeds
a c e r t a i n v a l u e d u r i n g s t a b l e d r i v i n g c o n d i t i o n s , t h e
sensor is considered deteriorated and the ECM sets a
DTC.
Starting Control
When the engine is started, the ECM provides a rich
mixture by increasing injector duration.
(cont'd)
11-23