Mystique Discuss the Mercury Mystique here...

Rough idle

Old 11-12-2004, 01:31 PM
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Join Date: Nov 2004
Location: United States
Posts: 2

Bought '99 Mystique 4 cylinder with 55k. Drove it home 45 miles and it ran like a champ. Stopped for dinner started right up and idled fine.

10 miles to go, put the headlights on, and the smoothness changed like right now. Pulled into my yard and very rough idle. Tried it this morning and it won't idle at all. Starts right up, but just won't idle.

Ive thought of the EGR, but how could it go so fast? I'm sure the headlights are not relevent, but any help anyone could give would be appreciated.

Old 11-15-2004, 01:54 PM
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Join Date: Oct 2004
Location: United States
Posts: 132

Check your charging system. Easy wat\y to do with out a meter is to start the car without any accessories on. Then start turning things on,one by one,to see when fault occurs. Lights,A/C,hazards,rear defrost,radio,etc. put an extra load on the battery,not the alternator. If your alt. or voltage regulator is bad,it will not send enough power back to the battery,therefore,you run a fault. If the alt./reg. are fine ,you should be getting approx. 1.4-1.9 v.d.c. back to the battery. This can be checked with a standard multimeter.


Old 11-15-2004, 03:36 PM
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Join Date: Nov 2004
Location: United States
Posts: 2

Thanks for the reply. I can check that but I don't think it is. Talked to someone at the Mercury Dlr and he said it was the Idle Air Control.

Was fooling with it today. It runs better when you pull the air horn off the motor. So I went and bought a MAF because I had another car do the same thing. I also cleaned the battery cables as they were a mess. Same thing.

It starts up fine. But within minutes, the idle starts loping like a big cam. When you take it out on the road, it's bucking all the time. When I pulled in my driveway, it stalled. But always starts right up.

I checked the vac lines all elect plugs buy nothing helps. I'm going to buy a scanner tomorrow and see what codes are in there............Thanks again..........Albert
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