Evaporative Emissions System: Testing and Inspection

Fig. 16 Evaporative Control System:

BMW has made many modifications to the evaporative control system. Check all applicable TSB's for latest EEC system update.
Check all vapor hoses for cracking, restrictions and good connections. It is important, that the fuel cap is in good condition and does not leak.
This engine is equipped with a thermostat valve and a vacuum controlled EEC purge valve (no wires to valve). They can be checked as follows:

- Check thermostat valve for correct operation. Valve (located on the thermostat housing) must be closed if coolant temperature is less than 33 ± 3°C (91 ± 5°F). It must be open if coolant temperature is above 46 ± 3°C (109 ± 5°F).
- If thermo-valve does not operate as described, replace and retest with new valve.
- Disconnect vacuum purge valve (located above valve cover, in intake bellows).
- Blow air through valve. Valve should be closed. If valve is stuck open, replace and retest with new valve.
- Remove small vacuum line at purge valve. Connect a vacuum pump to the purge valve and apply vacuum. Purge valve should open. If valve does not open, replace and retest with new valve.
- Disconnect vacuum pump and reinstall purge valve and vacuum line.