Porsche 924 Workshop Manual page 175

25
Fuel Mixture
924
CHECKING FREQUENCY VALVE FOR OXYGEN SENSOR CONTROL
1. Detach wire connectors.
2. Connect ohmmeter on frequency valve.
Coil resistance : 2 to 3 ohms.
3. Replace frequency valve if necessary.
REMOV ING AND INSTALLING FREQUENCY VALVE
Removing
1. Loosen fuel return line on solenoid and bracket for
frequency valve.
2. Loosen coupling nut (arrow) on frequency valve,
while counterholding on hexagon of fuel feed line.
I nsta lli ng
Frequency valve plug must face up, i.e. toward engine
cover, when installed.
25. 34
Checking Frequency Valve for Oxygen Sensor Control
Removing and Installing Frequency Valve
Printed in Germany