Fuel - Idle Speed Varies/Deviates From Specifications
88BMW01GROUP 13 Fuel System
Bulletin Number 13 03 88 (1589) Page 1 of 4
Montvale, NJ February 1988 Technical Dept.
SUBJECT: Idle Speed Fluctuation/Idle Speed Complaints
MODELS: 318i, 325e, 528e with VDO Idle Control System
Complaint: Idle speed fluctuates; idle speed deviates from specifications.
Cause: Adjustable metal idle control valve (ICV) requires adjustment.
Correction: Adjust the idle control valve using the following special equipment and procedure:
Procedure: Note: This procedure is intended as an aid in maintenance and repair, and is used only in conjunction with other labor operations.
Connect the idle control valve (ICV) current probe in series with the idle control valve and the ICV plug as shown.
Set up Fluke multimeter to read milliamps by placing the positive (red) lead in the jack marked "MA" and select the 2000 milliamp range.
3181/A
^ Connect multimeter to ICV current probe.
^ Connect BMW Service Tester and Digital Mixture Measurement unit.
^ Start engine (oil temperature should be a minimum of 140~F/C60~C).
^ Switch off air conditioning and all other electrical consumers.
^ Check current of the idle control valve with digital ammeter at the specified rpm as shown on BMW Service Tester. The current should be:
318i: 460 +/- 5mA at 850 +/- 50 rpm
318iA: 460 +/- 5mA at 750 +/- 50 rpm
If the mA and rpm readings are different from above, adjust idle control valve as follows:
1. Turn the adjustment screw on the side of the idle control valve clockwise (completely closed).
2. Slowly open the adjustment screw by turning counter-clockwise until 460 mA and the nominal rpm is reached.
NOTE: Do not turn screw too fast as you can easily overshoot the proper adjustment point.
^ Run Engine Test step 10 and assure CO (Voltage) adjustment is within specifications as per Technical Reference Information Bulletin 00 01 83 (2012).
If necessary adjust CO, then readjust milliamps and rpm to be within the above mentioned specification.
^ Disconnect BMW Service Tester and digital ammeter.
325e, 528e
^ Connect multimeter to ICV current probe.
^ Connect the BMW Service Tester and exhaust probes.
^ Start engine (oil temperature should be a minimum of 140~F/60~C).
^ Switch off air conditioning and all other electrical consumers.
^ Check current of the idle control valve with digital ammeter at the specified rpm as shown on BMW Service Tester. The current should be:
480 +/- 5mA at 700 +/- 50 rpm
^ If the mA and rpm readings are different from above, adjust idle control valve as follows:
1. Turn the adjustment screw on the side of the idle control valve clockwise (completely closed).
2. Slowly open the adjustment screw by turning counter-clockwise until 480 mA and the nominal rpm is reached.
NOTE: Do not turn screw too fast as you can easily overshoot the proper adjustment point.
^ Run Engine Test step 10 and assure CO adjustment is within specifications.
If necessary adjust CO and then readjust milliamps and rpm to be within the above mentioned specifications.
^ Disconnect BMW Service Tester and digital ammeter.
Idle Control System Troubleshooting
If, after following the adjustment procedure the idle speed continues to deviate from the specification, system troubleshooting should be undertaken.
1. Using the BMW Constant Current Generator determine whether the fault is with the idle control valve or the System.
2. With the current generator connected, the Idle Speed should return to specifications. If not, the valve is faulty and should be replaced.
3. If the engine does idle normally, the system is faulty and further troubleshooting should be performed using the idle control system diagnostics found in Group 13 of the Repair Manual.