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When my car is completely warmed up and at idle, the RPMs fall to a steady 700rpm, the headlights dim, the dash lights dim, and if I have the HVAC on, the speed slows. I'm pretty sure this only happens at night with the headlights on but I can't remember. I just recently brought my car down here to FL with me and I'm trying to fix the little problems.

I replaced the alternator last year with a reman'd from Advance Auto. I had this problem before the alternator swap. I just replaced the battery with a new Wal-Mart battery a week ago and that did not fix the problem either.

I searched a bit and found a thread where a few people commented saying they have a similar problem but it was a failing alternator and/or large stereo system. The alternator is a fresh reman'd and I just have a Panasonic head unit.

If this isn't a "problem" then I won't really concern myself with it but it would be nice if it were fixed. A quick rev to 1000rpm brings everything back to normal but it quickly drops back down to 700rpm. I have considered playing with the idle screw to try to bring the idle to 1000rpm but according to my Haynes manual, it should not be that high.
 

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Upgrade or at least change your engine ground wires. That makes one hell of a difference. Especially for the colder climates.
 

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mine does it all the time too.... if im at a red light at night my volts will drop down to like 10.5 or 11 and then when I rev it up a lil bit it will go back to almost 13 or 14 it is kinda stuipd but i think it is a common problem
 

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Mine does that too, although at this time of year its the heater and the rear defroster on instead of A/C. I've found the headlights to be among the worst at sucking power. If you turn 'em off, does the fan pick its speed back up?

I have a newer battery and I put in a new alternator last year. Its reasons like this I wished I had tried the 90amp Accord alternator instead of the stock 70amp Prelude alternator. I've heard of people shaving their alternator wheels to make them rev faster at the lower RPMs but I would be somewhat worried about my voltage regulator over time. It's just something I've learned to deal with mostly. I may try the ground wire upgrade this year, maybe that will help a little bit, but a beefier alternator is the only thing I think will work for me in the end.
 

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Well I'm glad (sort of) to see I'm not the only one. I wish I had done the Accord alternator upgrade as well but I was pressed for time because it was winter and I didn't have my Camaro to drive around because it was in storage. Now I live in FL so cold weather isn't a big deal but I think I will do the ground wire upgrade when I pick up some wire and have some free time. It seems pretty easy and I can see how crappy the original wires are.

Anyone have a spool of wire and want to sell enough for the upgrade? I really don't want a 25 ft. spool to use just a couple feet.
 

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you can buy it at Lowe's or the d-pot, or like i do just get negative battery ground wires from other cars at the junkyard, OEM quality and super big wire

but as for the problem, its common, old wire and whatnot, if its really an issue you could rise the idle a hair if you really wanted, but otherwise i'd just leave it, you don't need your headlights when you're stopped anyways...
 

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its a pretty common problem, and really isnt anything to be concerned about. you can bump the idle up to 750-800 if you really want to, but i wouldnt go any higher than that.
it can be caused by a bad quality battery or alternator or by bad grounds.
but even when everything is 100% perfect, it still often will do it.
the main cause of it is simply the alternator spinning too slowly by just a hair. which to me is a good thing, because it means honda did their research in finding the proper alternator speeds to offer the best function with the least resistance against being a power robber at higher rpms.
 

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Glad it's not just me. New battery, new alt, new grounds, and still dims at idle. The most annoying to me is the windshield wipers go sooo slow when idling and chatter a bit :p
 

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My 88 S did that. Ground wire upgrade helped a lot and almost resolved the problem. I put a new 650 CCA for a GMC Canyon 5-cyl. Haven't had the problem since.

Mostly, it's normal to have a little dim with all accessories turned on.
 

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go to your local stereo shop and pick up some 4awg wire you can also go to walmart and pick up a 4awg amp wiring kit if you dont want to spend the money on good wire. the scoshe wiring that walmart sells will make good enough wiring for ground but dont use it for stereos!
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its a common problem, like it was said earlier, the volts just drop when your coming to a stop or have your foot on the brakes at a light. its not a big deal.
 

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Someone had a group buy or something not that long ago for some pretty ground wires that were an upgrade you could grab, might even have choice of colors. I wanna say it was like $25 for the set, might be worth a quick search.

That was butterthegreat, however the GB never happened. It is so cheap to make your own wires anyway. Just go to Home Depot or Lowes, buy some copper wire which is coated and just some connectors. $15 tops.
 

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i replaced my ground wires and added a couple, it really helped out, even the windows roll up and down faster. my lights still dim at idle a little, its not as bad though.
 
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