When starting the engine with outside temperature pretty cold (< 0 deg F), the idle speed will drop down then up to normal speed; it will do it one or two times only. All becomes normal after that. This will happen within the ~ first minute after the engine is started. THANKS
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1998 Honda Accord Question: idle speed drops a couple of times when temperature < 0 deg F
Answer #1patrick mannion from Greg Solow's Engine Room, February 14, 2009, 13:36Master
Attached to the intake manifold at the top rear of the manifold (nearest the firewall) is an idle air control motor(IAC). The IAC can boost the idle speed 150 to 300 RPM when power steering is turned, electrical loads are turned on or the engine idle speed dips below specification. With a warmed up engine the idle speed with no loads on should be 750 RPM. I would remove the air induction boot/duct to the throttle housing. With the ignition key off open the throttle butterfly all the way, spray Chemtool around the throttle butterfly and clean with a soft tooth brush until the area is clean of carbon build up. Reattach the induction boot, If the idle speed needs to be raised there is a screw next to the map sensor that can be turned to raise the idle speed but adjusting this is a last resort and only adjusted if everything else is OK otherwise you are masking another problem. Do not turn the screw that at the throttle linkage to raise the idle speed. Cleaning the throttle butterfly area normally improves things if the ignition is OK and the engine is mechanicallly sound.