Honda idle relearn procedure?

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Patman

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Last week I got a new battery for my wife's 2000 Civic (with auto trans), and ever since then the idle has been very low. The same thing happened a couple of years ago when her battery died and we had to boost it. I remember it took a very long time for the idle to return to normal (many weeks!)

So I'm wondering if there is some sort of idle relearning procedure when you put in a new battery? It's idling so low it seems like it's going to stall, and it's very rough.
 
Sounds right to me.

Disconnecting the battery resets the ECU and some cars experience a drop in idle RPMs until the ECU re-learns the settings. This usally takes a few days, not weeks.
 
Well...when you removed the battery you reset the ECU, so it should be relearning the idle settings. 5 start-drive cycles is usually all you need.

Try a few starts and let it idle for a couple minutes. Don't touch the gas or brake during the procedure, and make sure all the accessories are off.
 
I'm not a Honda guy, but based on general knowledge, I assume it has some sort of throttle position sensor. If it's adjusted to an incorrect value, the car will idle wrong until it learns enough to overcome the issue. And the learning cycle usually requires 5 full cold to hot cycles, anything else may not really count as a cycle.
 
Not a Honda expert, but the idle learning process on some after market computers requires running the air conditioner as well for a few minutes as well as accessories that load the motor eg radio, lights etc.
 
How low?

My bros 94 civic ex auto idles just above 500rpm maybe closer to 550. has never stalled yet, and is very quiet and smooth at that low of an idle.
 
It is hard to read the tach exactly but it looks to be about 200rpm lower than before.

The problem is that this battery was put in a week ago, so the car has done a lot of hot/cold cycles since then and it still idles low and rough.

I'm going to try changing the plug wires today to see if that helps the roughness at least, since they are still the OEM wires (with 58k on them)

I tried idling the car last night for about 3-4min, and cycled through from park to reverse to neutral to drive and back.

Today I will try idling it again, but without touching the brake or gas, and I'll put the AC on as suggested too.

Is there a way to somehow manually raise the idle a little bit?
 
quote:

Originally posted by Patman:
Is there a way to somehow manually raise the idle a little bit?

Yes, there's a procedure in the shop manual, but I don't have it for that car/engine. But generally, there should be a idle adjusting screw on the throttle body. Turn it 1/4 turn at a time.

But you might want to check a few other things before you do that. Check to see if there's any DTCs set. Checking the ignition wires is a good idea. Check the brake pedal position switch circuit. Let me know how you make out.
 
427 knows hondas so listen to him.

I suspect a over used fuel filter Pat.
 
I changed the plug wires yesterday, plus let it idle a lot more (which I normally don't do!) and it's a lot better now. But the problem is that when the idle is even a tiny bit lower, there is something under the dash which vibrates, something is loose, so it gives off this low growl which is annoying.

The fuel filter has never been done Terry, so that is something that we'll have to get done early next year for sure. When they are doing that I'll get them to check the codes too.

I realized one thing which makes me not want to raise the idle manually though. I don't like how high it idles when cold, so if I raise it manually that will just get even worse!
 
quote:

Originally posted by Patman:
I changed the plug wires yesterday, plus let it idle a lot more (which I normally don't do!) and it's a lot better now. But the problem is that when the idle is even a tiny bit lower, there is something under the dash which vibrates, something is loose, so it gives off this low growl which is annoying.

The fuel filter has never been done Terry, so that is something that we'll have to get done early next year for sure. When they are doing that I'll get them to check the codes too.

I realized one thing which makes me not want to raise the idle manually though. I don't like how high it idles when cold, so if I raise it manually that will just get even worse!


hmm. how does it idle when cold? On my bros civic, when you start the engine when its cold, it starts right up, goes to about 1500rpm, and then slowly comes down as the fast idle/idle air control valve sees the engine warming up. Not rough at all. Is your rough when starting the engine cold?
 
Her engine is not rough at all on a cold start. It fires up right away but what I don't like is how it spikes up to 2000 rpm, holds there for about 5 seconds, then comes down to only about 1600 for a while, then it holds at 1500 for a few more minutes too. It just seems far too high for my liking. My car only holds at 1000 rpm right after a cold start.

I think her idle is now where it was before, but whatever is rattling under the dash or the hood is the most annoying part right now. If it weren't so darn cold (about -5F right now) I would check the battery hold-down to make sure there is nothing loose.
 
my 1990 suzuki sidekick roars up to 2500 for a few seconds, then kicks down to 2000 and stays like that for awhile... Its quite weird, and Im almost positive its not right since it makes the shifts very tricky.

Patman, my SS (ls1) never really cold idles above 1100-1200 in the coldest weather!
 
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