Very smooth ride, no problems. Today, drove slow in traffic with a/c on, idled for half hour with a/c. Then check engine light went on, idle surged wandering about 1000 rpm.
Shut car down. Restarted without A/C. Problem disappeared. Everything OK.
What could it be? Old 1990 BMW 325i.
90 325i surging rpm 1000, check engine light, A/C suspect
Moderator: martauto
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str255
- E30 Zone Newbie
- Posts: 3
- Joined: Fri Apr 15, 2016 11:00 pm
- Location: Las Vegas
problem, only happened when running idle for a long time. I think it's the A/C load. Try running at speed with A/C, or not using A/C at idle. 
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Brianmoooore
- E30 Zone Team Member
- Posts: 49359
- Joined: Mon Jan 10, 2005 11:00 pm
Idle speed should increased lightly when aircon is switched on. This is achieved by applying 12 volts from the aircon switch to a small 4(?) pin socket on the engine loom very close to the engine ECU. Check that this plug is connected.
Check that the throttle position switch is working correctly, and switching the ECU to the idle map at idle.
Check for inlet side air leaks.
Check that the throttle position switch is working correctly, and switching the ECU to the idle map at idle.
Check for inlet side air leaks.