I have a 1984 Nissan 4X4 that just started idling high once the temp dropped below freezing. It has high miles but regular maintenance. Manua, carbureted engine. I noticed that once it is VERY warmed up (like driving for at least 30 mins straight) is will return to normal. Any help would be appreciated.
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Re: High idle in cold weather
This is normal for a car of this age carburetor type motors have a automatic choke this is activating when you start your car as it is so cold i would not worries about it it is designed to make it easier to start your car when it is cold my car dose the same thing hope this helps ricko
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If it was doing it when cold I'd say definitely, but your problem is when warm right? Maybe throttle position sensor? The ICV is pretty expensive ($85 and up). Just to take it our of the equation maybe clean it. I've never done mine, but Googling it, it doesn't look overly hard. Hopefully you have a garage or better weather than I'm having today!!. Good luck. Hey, when you figure it out come back and let us know what it was.
You don't say what make of car but it's about the same for all. Your problem is the choke adjustment. The choke raises the idle when the car is cold and after warm up drops to normal. You are doing the chokes job when you hold the pedal down, once its warmed up the choke no longer functions till cold again. So check the choke and the high idle speed adjustment. Simple fix. Hope this helps mike
It likely has EFI (electronic fuel injection) and an idle air control valve that regulate idle speed. They can get gummed and fail to have a fast idle when cold, or get stuck the other way, and have a too fast idle all the or regularly take its time slowing down after you take your foot off the gas. An engine temp sensor can also cause a lingering high idle if it reports the engine as still being cold after warm up.
check the MAP sensor (manifold absolute pressure). The ECM (car computer) uses that to keep idle at minimum 750 RPM. It's normal for it to run high when cold. These small 4 banger motors typically run hot, and they won't run right IF they're NOT running hot, ergo the idle is usually high when it is cold so as to cause it to warm up quicker. If the RPM's drop below 750, suspect the MAP sensor, &/or ECM.
First check the error codes. they can be a lifesaver. Physically look under the hood for cracked or leaky vaccuum hoses. High idling often indicates a vaccuum leak somewhere. look at the vaccuum elbows on both the right and left side of the engine just about midway down the engine from front to back on the plenum- that's the big, black flat assy that channels the air as it goes into the engine. Once again the codes can tell us alot.
I have a 2001 Nissan Altima and mine did the same thing. We replaced the intake gasket. It costs around $5.50, but it requires several different kinds of tools. We spent over $100 in special sockets, etc. But once you replace that gasket, it will idle better.
Hondas are famous for this, my accord does it. This is normal UNLESS it still idles high after normal running temp. has occured. Watch your temp. gauge when it reaches normal temp tap the gas a little bit if the idle drops then it is fine