Evaporative Emission Control - MIL ON DTC's Stored
GROUP 16Fuel Supply System
Bulletin Number
16 05 97
Woodcliff Lake, NJ
August 1997
Product Engineering
SUBJECT:
Evaporative Emission Control - On-Board Diagnostic System
MODEL:
E36 - 318i and Z3 with M44 as of 1/97
E36 - 328i and as of 10/95
E36 - M3 as of 3/96
Z3 with M52 as of 10/96
E38 - 7401/iL and 750iL as of 5/97
Situation:
Customer complains that the "Check Engine" lamp is illuminated and one or more of the following faults are set in the Engine Control Module (DME):
M52 Engine:
251 - Tank venting system, minor leak
252 - Tank ventilation
253 - Shut-off valve, activated charcoal filter, jammed shut
OR
254 - Tank venting system, major leak
M44, M62 or M73 Engine:
94 - Tank venting system, major leak
96 - Shut-off valve, activated charcoal filter, jammed shut
OR
97 - Tank venting system, minor leak
For purpose of leak detection the "Check Engine" lamp will only be illuminated if the fault is present during two consecutive "driving cycles".
A "driving cycle" consists of the DME conducting a self test of the following OBD II diagnostic functions once per vehicle operation (engine start-up - drive - engine shutoff):
-- Evaporative system - component functional check
-- Evaporative system leak detection
-- Tank venting/shutoff valve operation
-- Monitoring catalytic converter efficiency
-- Secondary air induction operation
In order to complete a check of these systems the vehicle must be operated in a manner which allows these functions to be fully executed. In most cases any attempt to duplicate the specific driving condition required to fully execute the above listed self test will be unsuccessful therefore it is recommended that the test modules via DIS and/or BMW specific test tools be utilized.
The following troubleshooting information has been obtained from field evaluations, hotline contacts and pink sheets:
1. If a fault pertaining to a major leak (FC 94 or 254) or minor leak (FC 251 or 97) are present:
-- Check if the fuel filler cap is properly installed. If the cap can be easily pulled off, the fault was set as a result of an improperly installed fuel filler cap.
-- Properly install the cap.
-- Printout the fault information
-- Clear the fault
-- Select "Service functions"
-- Select "DME system test"
-- Select "3. Leakage diagnosis, tank venting system"
NOTE:
If the fault does not re-occur with the fuel filler cap properly Installed there Is no need for any further diagnosis.
-- If the fault returns the system should be checked further for leaks by using the Evaporative System Leak Test Tool (P/N 90 88 6 161 150) in conjunction with an A/C leak detector.
NOTE:
The shut-off valve must be activated/powered closed when using the leak test tool. Refer to the instructions given in section 16 00 100 of the Repair Manual.
The following component checks should also be made if no leak is detected using the Leak Test
Tool:
-- Check that fuel filler cap gasket is not damaged.
-- Check operation of purge valve using test modules on DIS.
-- Check/test purge valve using a hand held vacuum pump to assure the valve is able to hold a vacuum.
-- Check that the O-ring used to seal vacuum hose at purge valve is properly seated/installed.
-- Check for possible broken hose fittings in area of expansion tank.
-- Check the operation of the shut-off valve using test modules on DIS.
-- Check that the shut-off valve is properly seated/installed into the charcoal canister.
-- Check routing of hose going to the fuel tank pressure sensor. The hose should not be pinched in anyway, if it is pinched the hose should be rerouted or shortened (see illustrations in step 2).
2. For faults pertaining to the Shut-off Valve check the following:
-- Routing of hose going to the fuel tank pressure sensor. The hose should not be pinched in anyway, if it is pinched the hose should be rerouted or shortened (see illustrations).
Hose to fuel tank pressure sensor pinched/routed incorrectly.
Hose to fuel tank pressure sensor not restricted/routed correctly.
-- Operation of Shut-off Valve, Purge Valve and Fuel Tank Pressure Sensor using test modules on DIS.
-- Remove the shut-off valve from the charcoal canister and look for any obstruction which is not allowing the valve to shut completely.
Warranty Information: For information only.