Fuel - Erratic Rough Idle at High Ambient Temperatures

Bulletin Number:
13 06 82 (632)

Date:
September, 1982

Group: 13
Fuel Supply and Adjustment

Subject:
ERRATIC ROUGH IDLE

Models:
1982 528e, 633CSi, 733i

An erratic rough idle may be encountered during high ambient temperatures. This condition is do to an excessive rate of fuel vapor accumulation in the evaporative control system.

When the rough idle occurs, remove the purge line between the charcoal cannister and purge valve. If the idle smooths out, perform the following modification which will cause the purge valve to close off the purge line anytime the throttle is returned to idle.


PROCEDURE

1. Using a 3M quick connector, splice one end of a jumper wire (approximately 24" long) to the brown/blue wire of the throttle butterfly switch connector plug. This will require slicing open the grey harness wrap of the throttle butterfly switch connector wiring approximately 3" - 4" from the plug.




2. Splice a male/female inline (air conditioning) diode, P/N 61 31 1 358 268, into the jumper wire using male/female spade connectors as shown in the illustration.


IMPORTANT:
MAKE SURE THE DIODE IS INSTALLED IN THE CORRECT DIRECTION. (See illustration.)







3. Splice the remaining end of the jumper wire into the green/brown wire of the purge valve relay plug which is clipped to the side of the fuse box. (See Images.)


IMPORTANT:
THE PURGE VALVE RELAY MAY NOT BE INSTALLED IN THE SAME POSITION ON ALL VEHICLES. VERIFY THE CORRECT RELAY BEFORE SPLICING INTO THE WIRING.

4. When completed, position the jumper wire away from hot or sharp objects using several wire ties.


IMPORTANT:
RECALIBRATION OF THE THROTTLE SET SCREW AS OUTLINED IN TECHNICAL REFERENCE BULLETIN 11 O2 82 (2008), PAGE 3, MUST BE PERFORMED ON ALL 528e MODELS.