 Figure 1:MPC (L-Jetronic) Pressure Sensor |
Question: How can I tell if my electronic
fuel injection pressure sensor is working ok? Answer: The 914 pressure sensor found on the MPC injected cars (1.7L and 2.0L) is often prone to failure (shown Figure 1). One method of testing the pressure sensor is to see if it will pull vacuum. Place a vacuum on the input of the sensor either with a gauge, or you can use your mouth. The pressure sensor should pretty much be able to hold a vacuum continuously. If the vacuum leaks out, then most likely, the pressure sensor needs replacement. With a faulty pressure sensor, the car will run very rich at idle, if at all. The pressure sensor senses engine vacuum. When the sensor fails, the engine will think that it is running at high rpm, and requires more fuel to be injected into the injectors. This will make the car run very rich at idle, and may even dilute your engine oil with gasoline. When the sensor is operating properly, the diaphragm within the sensor is displaced when the engine vacuum is high (at idle). This displacement tells the FI computer to run lean. When the engine runs at high RPM, the pressure sensor has very little vacuum on it, and thus tells the FI computer to run richer. |
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