# Rough Idle with lights on



## Grambo427 (Jan 24, 2013)

So it's been awhile since I last visited the forum but some research has got me worried. The car has recently picked up a rough idle after it comes to temperature and is most notable with the headlights and or fog lights on. No CEL nor warning message. I was thinking it was the alternator but some digging has me worried about broken valve spring/valvetrain parts. Any one have a similar experience?


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## Grambo427 (Jan 24, 2013)

update: popped the valve covers off to check for broken springs. I didn't see any obvious signs of failure, just some oil puddling on the last to valves (rear most, driver side) but i think that has to do with the floor in the garage. Could there be something i'm missing or should look for in particular?


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## svede1212 (Nov 1, 2005)

Oil puddles there because the engine is tipped a little plus acceleration.  I'd check your battery voltage with a meter at idle and see what you have. Harbor Freight has digital ones for $5-10 if you don't have or can borrow one.


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## Grambo427 (Jan 24, 2013)

Thanks svede!!! I'm planning on checking that this weekend. Battery is yellow top optima and it's just over a year old. I'm thinking the alternator is giving up (least I hope that's the cause). I'll post back with any info.


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## svede1212 (Nov 1, 2005)

FWIW I've had two Optimas (redtops) on my GTO and they both crapped out on me. I will never get one of those again. The second one even leaked which they aren't supposed to do.


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## Grambo427 (Jan 24, 2013)

So got some updates on this. And sorry for the vague description of symptoms. The rough idle is actually revving to idle and dying down (like it's choking off), then coming back up. At one point at 80 mph in 6th I hit the window switch and the engine burped. Voltage at battery with the car off was right at 12-12.1 V. Had the alternator and battery tested and both passed. Haven't been able to get the car to repeat the symptoms to video. Alternator does whine just a hair when load is first applied (headlights turned on) but doesn't continue. Also noticed that the backlight for my window switches and headlight switch stays on even when the headlights are off. Is this normal? Kinda stumped so far and don't want to buy a new battery and alternator unless absolutely necessary. 

Thanks
G


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## Grambo427 (Jan 24, 2013)

Voltage with car on at idle was 13.8.


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