Vacuum Valve
- Connect Bosch Tester (KDJE 7453) to 2-pole test socket located in front of fuse box for testing fixed pulses of Lambda system. Operate engine at 875 RPM. Disconnect wiring connector from vacuum valve.
- Using voltmeter, check that 12 volts exists between vacuum valve connector and ground. Install connector on vacuum valve. Increase engine speed to 2000 RPM. Release accelerator suddenly.
- Feel vacuum valve to see if operation is felt. Sharp reduction in engine RPM indicates that vacuum valve is working. Check that fixed pulse relation of Lambda system is 60% until system cuts out at 1375F75 RPM.
- If fuel cut-off does not work, check for defective deceleration relay, acceleration enrichment time relay, throttle switch or fuel shut-off valve. See BOSCH CIS (LAMBDA) SYSTEM in the FUEL INJECTION section.
- If incorrect pulse ratio is obtained, check for defective deceleration relay, acceleration enrichment time relay, throttle switch, pulse relation valve or Lambda control unit. See BOSCH CIS (LAMBDA) SYSTEM in the FUEL INJECTION section.
Courtesy of SAAB-SCANIA OF AMERICA, INC.