Idle Speed - Reduces When Lights Are Turned On

[Phil205 1 1 Cars]

Is it normal that the idle speed drops by 10-20 % when the lights are turned on ?

 

I have to keep the idle speed about 1200 rpm (with lights off) to prevent stalling when the lights are turned on.

 

The car had a new battery recently. The measured volts does drop a bit under load.

 

Is this drop in idle speed normal or is the alternator not putting out enough current ?

 

Or should I look elsewhere for a the problem ?

 

[Anthony 1,002]

A small drop in idle speed is normal, as the Jetronic management cars have no way of compensating for additional load on the engine.

 

However, if you're having to raise the idle to 1200rpm to stop it cutting out when you've some electrical load applied, then that's not right.

 

Usually this is down to poor setup in my experience. Start with the idle mixture and ignition advance, together with cleaning out the throttle body and breathers, and go from there.

[ian010778 21]

I had more or less the same with my 1.6

 

As Anthony said, after a good cleaning and setup it is now fine. The major difference came when I altered the ignition timing though but any blocked breathers, air leaks and general dirt in the throttle body/under the idle speed screw will hurt the idle.