Engine Controls - Check Engine Lamp/Misfire Faults
Group 12Engine Electrical
Bulletin Number
12 05 97
Woodcliff Lake, NJ
April 1997
Product Engineering
SUBJECT:
M62 Misfire faults
MODEL:
E31 - 840iA (11/95-10/96)
E38 - 740i/iLA (12/95-10/96)
E39 - 540i/iA (3/96-10/96)
Complaint:
Customer Complaint that the "Check Engine" Lamp is illuminated and:
^ Fault Codes 50, 51, 52, 53, 54, 55, 56 or 57 are set in the Engine Control Module (DME)
Cause:
A misfire fault(s) will set if:
^ the total misfire count of one or more cylinder(s) exceeds a predetermined value of misfires per 1000 engine revolutions.
The check engine light will be illuminated:
^ if a particular misfire fault is set for the second time after exceeding a predetermined value of misfires per 1000 engine revolutions.
^ immediately if the total count exceeds a predetermined value of misfires per 200 engine revolutions.
The DME obtains its cylinder reference information from the Crankshaft Position Sensor. If the signal is implausible an erroneous reference mark can be obtained by the DME which will result in a misfire fault being set.
Possible causes of cylinder misfire faults (items identified by * indicate actual field findings):
^ Vehicle ran low or out of fuel
^ Poor fuel quality (ex. water in fuel, customer uses an additive, etc.)
^ Low/high fuel pressure
^ *Ignition coil
^ Fouled spark plug(s)
^ Restricted / contaminated fuel injector(s)
^ Crankshaft position sensor
^ Poor combustion due to low compression or high leakage
^ *Blocked/restricted Catalyst
Correction:
An enhanced misfire detection/determination algorithm has been developed and integrated into the latest programming software package. The latest programming software was introduced into production as of 10/96.
If there is a component/hardware failure (reproducible fault) a modified DME program will not fix the problem.
Whenever possible it is important to try and operate the vehicle under the same conditions at which the fault occurred.
1. If fault is reproducible:
^ Check the items listed above as a possible cause.
2. Vehicles produced (12/95-9/96) should be reprogrammed using MODIC programming software P9.0 or higher, if it has not already been updated.
Procedure:
Whenever possible it is important to try and operate the vehicle under the same conditions at which the fault occurred.
Example: Misfire fault occurred at 2000 RPM
Test/Evaluate: Operate the vehicle at 2000 RPM under various load conditions to determine if fault will reset.
1. If fault is reproducible:
^ Check secondary voltage pattern
^ Check for damaged/restricted catalyst by lightly taping catalyst and listening for a rattle.
^ Check items listed above as possible cause
^ Reprogram DME, based on production date, once the fault has been repaired.
2. If the fault is no longer reproducible and the production date of the vehicle is 12/95 - 9/96 the DME should be reprogrammed using MODIC programming software P9.0 or higher, if it has not already been updated.
Vehicles produced prior to 10/96 that have not been updated will have one of the numbers displayed as the part number for a "Programmed control unit":
If one of these numbers is displayed the control module should be reprogrammed as indicated in S.I. 12 05 96 dated July 1996.
Warranty Information:
Parts and labor will be reimbursable under the terms of the applicable BMW Emissions Warranty.
Defect Code: 10 32 00 42 00
Labor Operation: 12 14 710
Labor Allowance: 6 FRU (E31)
6 FRU (E38)
7 FRU (E39)
Labor Operation: 12 00 009 Troubleshooting-Test/Evaluate
Labor Allowance: 10 FRU