Contour Enthusiasts Group Archives Forums Modifications Zetec Maintenance oddities at idle

I just noticed today that if i turn on the rear defrost while i am at a redlight my car seems to idle a little ruff and sounds like it is suddenly under more of a load. Is this normal.

not usre if it is good or not, I have noticed the idle go up on my car when i turn the rear defroster on


but then again I get the head lights dimming when I put the clutch in to stop, and I hear a idle difference, not rough, when closing the windows so it might be fine

Both you all have similar problems ie; your rear defrost/power windows and headlights coming on and making your engines idle differently/lower. While the Zetec 2.0 liter is a great motor, at idle it's probably only making a couple horsepower. When you turn on a large electrical drain item like rear defrosts, etc it puts a drain on the electrical system and the alternator pulls the engine rpms down a little. I would definitely check the condition of your battery or see if maybe your battery has the correct amperage rating for your car. But it's nothing to worry about, it's fairly normal. Hope this helps, Ken

I believe that if all is working correctly, the idle should come up a bit when the rear defroster, lights, etc are
turned on. The computer should be adjusting the idle to compensate for the alternator drag.
At least mine does.