19
FUEL SYSTEM
Basic ignition timing
Ignition timing compensation
MEMS provides the optimum ignition timing for the
relevant engine speed and load. The speed and
position of the engine is detected by the crankshaft
sensor which is bolted to, and projects through the
engine adapter plate.
Coolant temperature sensor
When the ECM receives a low engine temperature
signal from the coolant sensor, it provides optimum
driveability and emissions by advancing or retarding
the ignition timing.
The sensor incorporates an armature which runs
adjacent to a reluctor insert in the flywheel, the insert
consisting of 34 poles spaced at 10 °intervals, with
two missing poles 180 °apart to identify the T.D.C.
positions.
Knock sensor
The knock sensor is a capacitive device mounted in
the cylinder block between nos. 2 and 3 cylinders
below the inlet manifold. The sensor monitors noise
and vibration in the engine and passes this
information to the ECM which is able to identify the
characteristics of the knocking and make the
necessary corrections to the ignition timing of
individual cylinders.
The sensor ’reads’ these poles to provide a constant
up-date of engine speed and crankshaft position to
the ECM
The load signal is provided by the manifold absolute
pressure sensor mounted inside the ECM casing
which detects manifold pressure via a hose connected
to the manifold chamber. The sensor converts
pressure variations into graduated electrical signals
which can be read by the ECM
Idle speed control
When the throttle pedal is released and the engine is
at idle, the ECM uses the fast response of ignition
timing to assist idle speed control.
When loads are placed on, or removed from the
engine the ECM senses the change in engine speed
and in conjuction with the opening of the throttle disc
by the stepper motor, advances or retards the ignition
timing to maintain the specified idle speed. When load
is removed from the engine and the stepper motor
returns to it’s original position, the ignition timing
returns to the idle setting.
NOTE: Due to the sensitivity of this system
the ignition timing will be constantly
changing at idle speed.
2
DESCRIPTION AND OPERATION
| Categories | Land Rover Discovery, Range Rover |
|---|---|
| Tags | Land Rover |
| Model Year | 1995 |
| Download File |
|
| Document Type | Workshop Manual |
| Language | English |
| Product Name | Discovery |
| Product Brand | Land Rover |
| Document File Type | |
| Publisher | landrover.com |
| Wikipedia's Page | http://en.wikipedia.org/wiki/Land_Rover |
| Copyright | Attribution Non-commercial |
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