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Old 01-31-2013, 01:43 AM   #1
Capt. Obvious!
Focus Jr. Enthusiast
Join Date: Jan 2013
Fan#: 108055
Location: Where ever Uncle Sam says, Not Listed
What I Drive: 04 ZX3 S/C, 87 VW cabby, 98 Opel

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Pulling my hair out! Battery? alternator? Grounds?

When I turn my headlights on at idle, it bogs the engine down and kills it. I has been doing this for a couple weeks now.

First it did it a couple times till, it killed the battery enough that the car wouldn't start. Charged the battery up, drove it around a little bit, started it a couple times let it idle for a while, had the battery tested and they said it was fine, readings were all within spec for that battery. Drove it for about an hour and a half. Drove just fine, although the radio kept going off. I noticed that when I get to a stop light, sometimes it would idle really low and rough. Got home drove it a couple times on short trips and then the lights started killing it again. At this point I decided it must be the alternator. Charged the battery, changed the alternator, tested the voltage with the car running (14.?v) drives fine (still rough at idle occasionally), for about two days. Dies with headlights again last night. Battery is too weak to start the car, so I checked the voltage, it was low (11.9v) So I checked the voltage at various points to see if I had a bad ground, nothing really stood out.

I tested the following points with the engine off (11.9v wont start it) and all the accesories off.

Accross the + and - terminal of the Batt (11.9v)
+ terminal to cylinder head (11.9v)
+ terminal to various chassis points (11.9v)
+ terminal to alternator housing (11.9v)

I'm considering getting a new battery today, maybe the battery tester was wrong. Any other advice before I go blow $100 on a battery I may not need, two days before I leave for vacation???

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