i have a 96 honda civic coupe standard. it idles fine in neutral but as soon as on 1996 Honda Civic

you start to drive it revs from high to low constantly until you get going like 40 plus but when you slow down it will start reving high to low constantly unless in neutral again. any ideas? diagnostic code said idle sensor but already replaced that

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2 answers 3 comments
idle sensor??? no such sensor. anyway, most common reson for the erratic idle on honda is low coolant allowing the coolant sensor to come out of water. fill it up and see if there is any difference.

well i believe it was called idle air control valve. i also believe it has plenty of coolant because after running it the coolant overfill has coolant bubbling in it but ill check. like i said its only when i'm in low gears. it idles high to low consistently. But thank you for your advice. do you think it could be the throttle position sensor. I'm open to ideas. thanks again
Coolant level is important and causes idle sped fluctuation and surging. Throttle position fault should set a code but it would cause a flat spot on initial acceleration and would affect fuel cut off, vacuum leaks at the intake manifold gasket would affect idle quality and emissions (high hydro carbons). Its been a while since I worked on one with that problem but there is wax element for cold fast idle control,you take off the air boot at the throttle housing and put your finger over an air by pass chamber in the throttle housing with the engine warm if the idle improves the element is bad. Find a shop that specialize n Honda/Acura cars they will recognize the problem and know how to fix it. There is a company that independent auto repair shops get their information from, this same information is available inexpensively for people that work on their own cars.. The information is year make and model specific, covering repair procedures, torque specifications, fluid capacities and specifications, service bulletins, component locations, wiring diagrams ect.... Alldata is very easy to navigate http://bit.ly/AllData_Repair_Manuals_Online
hi Pat

thanks pat very helpful