Effect on Ignition

PURPOSE
Coolant sensor input is a variable factored into IGNITION ECM timing calculations. Optimum timing differs with engine temperature fluctuations as it does with engine speed and throttle position.

OPERATION
The coolant sensor is a thermistor device whose resistance varies with engine temperature. The ECM is programmed to recognize these resistance changes as temperature fluctuations. Resistance/temperature relationship is as follows:

TEMP (°F / °C) OHMS

50 / 10 4.4K
68 / 20 2.5K
86 / 30 1.6K
104 / 40 1.2K
122 / 50 840
140 / 60 630
158 / 70 470
176 / 80 320
194 / 90 210

Coolant Temperature Sensor:

LOCATION
Mounted in right thermostat housing.