my motor idles up and down at idle, yet it runs fine other wise. all vaccum hoses are connected. the motor is a b16 that i had swapped in. some times though when it does idle steady it revs at 2000 rpm's.. someone told me to check my ecu and what the lights are doing but i dont know where to look for that.

 

Throttle positiong sensor needs to be adjusted. Mine did the same thing. and also, if it just reves high...like 2000rpm...check the fast idel swithch (im not sure of the name) under the TB. make sure the plunger hasn't unscrewed all the way. hope that helps.

 

^^^ what he said...TPS is misbehaving.

 

if you dont have a check engine light on it is not your iac valve. if you have a hissing sound from your intake pull your intake hose and cover the top hole on the inside left of your throttle body. if your idle steadies out it is your FIT valve or Fast Idle Thermo valve. it mounts under your throttle body and contains a small thermostat that, based on water temperature will cause a small vaccum leak to raise the idle for warm up. I had the same problem and it was because the plastic ring that centers the thermostat had come loose. you can take off the back plate and adjust the ring, but if that doesnt work, it is not a cheap part to buy new. good luck. Oh yeah, if there is an air bubble in the FIT valve it could cause the idle to stay higher than normal but I am not sure that it would cause it to fluctuate. Even so, you could try to bleed your water system.

 

Yep. Same thing happened to my friend in his hatchy. I wouldn't fix it if I were you. Chicks dig it. Just tell them you have a cam.

 

Might also happen if you have a leak in your intake manifold gasket.

 

dont think its the TPS. This is a sensor that yousouldnt have to usually ever adjust. Now if its come out or unscrewed thats one thing. But if the original paint is still matched up dont mess with it. The problem is osmehting else and you would just be covering it up . Usually this is tune up related. PCV, fuel filter, and maybe plugs. This should fix the problem. Check to see if you are drawing positive vacume on he intake hole on the valve cover and likewise the opposite on the pcv side. USually if your arnt drawing vacume out of the PCV thats one of the causes. The manifold is searching for pressure and cant find it cause the PCV is clogged.

Try these things before going and adjusting factory settings.