User Manual - Page 35

For 2002 NISSAN MAXIMA.

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System Description
NFEC0015S02
SEF742M
The ignition timing is controlled by the ECM to maintain the best air-fuel ratio for every running condition of
the engine. The ignition timing data is stored in the ECM. This data forms the map shown.
The ECM receives information such as the injection pulse width and camshaft position sensor signal. Com-
puting this information, ignition signals are transmitted to the power transistor.
e.g., N: 1,800 rpm, Tp: 1.50 msec
A °BTDC
During the following conditions, the ignition timing is revised by the ECM according to the other data stored
in the ECM.
I At starting
I During warm-up
I At idle
I At low battery voltage
I During acceleration
The knock sensor retard system is designed only for emergencies. The basic ignition timing is programmed
within the anti-knocking zone, if recommended fuel is used under dry conditions. The retard system does not
operate under normal driving conditions. If engine knocking occurs, the knock sensor monitors the condition.
The signal is transmitted to the ECM. The ECM retards the ignition timing to eliminate the knocking condition.
Air Conditioning Cut Control
DESCRIPTION
NFEC0016
Input/Output Signal Chart
NFEC0016S01
Sensor Input Signal to ECM ECM function Actuator
Air conditioner switch Air conditioner “ON” signal
Air conditioner cut
control
Air conditioner relay
Throttle position sensor Throttle valve opening angle
Crankshaft position sensor (POS) Engine speed
Engine coolant temperature sensor Engine coolant temperature
Ignition switch Start signal
Vehicle speed (From combination meter) Vehicle speed
Refrigerant pressure sensor Refrigerant pressure
Power steering pressure sensor Power steering operation
System Description
NFEC0016S02
This system improves engine operation when the air conditioner is used.
Under the following conditions, the air conditioner is turned off.
I When the accelerator pedal is fully depressed.
I When cranking the engine.
I At high engine speeds.
I When the engine coolant temperature becomes excessively high.
I When operating power steering during low engine speed or low vehicle speed.
GI
MA
EM
LC
FE
CL
MT
AT
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
ENGINE AND EMISSION BASIC CONTROL SYSTEM DESCRIPTION
Electronic Ignition (EI) System (Cont’d)
EC-35
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