Rough low idle when cold, then after a minute good idle??? - Honda Civic Forum

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Rough low idle when cold, then after a minute good idle???

 

 
 
 
Old 12-21-2009
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Rough low idle when cold, then after a minute good idle???

Ok im new to hondas especially modded hondas. This 1 has a jdm b18c. Its a 99 civic. Also has headers(1 has a hole), adjustable cam gears, Aem fuel rail
weapon R intake, old skool skunk 2 IM. Anyways the car idles rough when cold for a minute or 2. Then after a few minutes it runs smooth and is fine. The owner told me its because its modded and all hondas run rough when cold until they warm up. He said you are supposed to let it warm up for a few minutes or press the throttle a bit till it warms up. Is this normal? Like i said im new to this, but it sounds odd. Ive been around plenty of hondas and none of them idled rough when cold unless there was a problem. I havent bought the car yet but won it on ebay. Im supposed to go see it. The ebay ad said it ran smooth with no problems other than the valves needed adjusting. Can someone shed some light and help me out. I dont want to buy a piece of junk.
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Old 12-21-2009
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Re: Rough low idle when cold, then after a minute good idle???

try to clean the idle air valve, which is near the throttle body and has two coolant hoses running into it. that controls how the car idles when the gas is not being pressed. im pretty sure that will fix it. the b18c is a type-r integra motor and may require premium fuel as well. has the car been tuned with the new mods?
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Old 12-21-2009
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Re: Rough low idle when cold, then after a minute good idle???

Im really not sure if it has been tuned. He told me it always runs rough when cold for a minute or 2 then its smooth. He said that was how modded hondas run so i dont know. Im looking at buying it. Actually already won it on ebay but i didnt know it idled so rough. If its just idle control valve thats no big deal, but im worried it might be head gasket leaking slightly or overreved engine. He says it runs smooth after the first minute of warming up. I need to ask him what fuel he is running. He also mentioned the header has a hole in it.
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Old 12-21-2009
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Re: Rough low idle when cold, then after a minute good idle???

here is a video he sent me of it idling and starting

Last edited by boostnm3; 12-21-2009 at 12:00 PM. Reason: Video
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Old 12-21-2009
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Re: Rough low idle when cold, then after a minute good idle???

hole in the header could cause issues, i would get that fixed and clean the idle valve. but doesnt sound like a serious issue. theres no way to know til you get it tho and look at fluids and other stuff. its possible it runs rough for the first few mins due to small coolant leak from the headgasket into the cylinders, which has to be burned off before the car will run normal.
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Old 12-21-2009
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Re: Rough low idle when cold, then after a minute good idle???

thanks for the response man. he said it drives great other than that first minute of low idle. the header does have a hold in it that needs to be welded shut. Im hoping its nothing serious because the car is clean
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Old 12-21-2009
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Re: Rough low idle when cold, then after a minute good idle???

yeah they are strong motors, im sure its not gonna have big issues.
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Old 12-22-2009
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Re: Rough low idle when cold, then after a minute good idle???

ok here are few more vids he sent me to show me how it runs when warm and cold.

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Old 12-22-2009
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Re: Rough low idle when cold, then after a minute good idle???

Here it is warmed up

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Old 12-22-2009
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Re: Rough low idle when cold, then after a minute good idle???

Every car will run rough when its cold and u first crunk it on... But fix that header leak first.
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