MEFI Fuel Injection
Engine Coolant Temperature Sensor (ECT)
The ECM uses the ECT signal to calculate engine temperature to determine if the engine is cold, at normal operating temperature or overheating. The MEFI 4 engines have a temperature controlled rev limiter. The purpose of this is to prevent engine damage from running a cold engine at high RPM. This feature will prevent the engine from achieving full RPM until it has reached operating temperature. The approximate limits are as follows: 68 degrees F……4000 rpm. 104 degrees F…..4600 rpm. 140 degrees F+…Full throttle operating range. Note: different engines have different rpm limits, however above approximately 140 degrees F all engines are allowed max rpm. (Unplugging this sensor will default the Scan tool to -39 degrees F, the ECM will be using an non-displayed default value).
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