Eldorado Touring V8-4.6L VIN 9 (1998)
Varying octane levels in gasoline can cause detonation in high performance engines. Detonation is sometimes called spark knock. Spark knock
causes the pistons and rings to vibrate and rattle producing the spark knocking sound.
DESCRIPTION
To control spark knock a Knock Sensor (KS) is used. This system is designed to retard spark timing to reduce spark knock in the engine. This
allows the engine to use maximum spark advance to improve driveability and to improve fuel economy.
The Knock Sensor system has two major components:
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The KS module.
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The Knock Sensor.
OPERATION
The knock sensor is mounted into the engine block under the intake manifold. The knock sensor produces an AC voltage which increases with the
severity of the knock. This signal voltage inputs to the Powertrain Control Module (PCM). The PCM then adjusts the Ignition Control (IC) to
reduce spark knocking.
EGR Pintle Position Sensor
EGR PINTLE POSITION SENSOR
The PCM monitors the EGR valve pintle position input to ensure that the valve responds properly to commands from the PCM and to detect a
fault if the pintle position sensor and control circuits are open or shorted. If the PCM detects a pintle position signal voltage outside the normal
range of the pintle position sensor, or a signal voltage than is not within a tolerance considered acceptable for proper EGR system operation, the
PCM will set a DTC.
EVAP Fuel Tank Pressure Sensor
DESCRIPTION
The EVAP Fuel Tank Pressure Sensor is mounted to the Modular Fuel Sender assembly.
OPERATION
The EVAP Pressure sensor is a sensor that changes resistance based upon fuel tank pressure (or vacuum). A vacuum is considered negative pressure.
The PCM provides a 5 volt reference and ground. The EVAP Pressure sensor signal varies between ground and 5 volts as fuel tank pressure varies. As
pressure decreases (negative pressure, or vacuum), voltage increases. As pressure increases, voltage decreases (positive pressure, low voltage). The PCM
uses the EVAP Pressure sensor values as an indicator of EVAP system efficiency.
Vehicle Speed Sensor (VSS)
Vehicle Speed Sensor
DESCRIPTION
The Vehicle Speed Sensor (VSS) is a pulse generator mounted in the transaxle. A toothed reluctor ring rotates near a magnetic pickup which
produces a varying voltage signal in the pickup coil. This voltage signal varies in proportion to vehicle speed and is sent to the PCM, where it is
converted to MPH.
