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Q:

idle surge up and down especially with headlights on on 1990 Honda CRX

Rookie cbe0621eac06868b3efe0d8d1d3611e23c60d3114864ea2ec19a68cfbd3eebab
battery checks 12.45v before engine start...after engine start battery checks 14.19v... if you rev motor up just alittle battery voltage starts dropping slowly down to 12.50v....when engine is warm and with headlights on idle surges up and down if headlights turned off surge stops. please help
(1) Answer
Your voltage readings indicate that the alternator is not working correctly on your 1990 Honda CRX. A low voltage condition when the headlights are turned on could be the cause of your idle surge. Please check connections and proper inputs to your alternator before assuming it is faulty.