idle up and down?

[vancem3m3]

my b18 idles up and down anyone know why?

[.blank cd]

IACV

[.blank cd]

Cold weather, probably fast idle thermo valve

[AnTi-PooN]

TPS

[SDBCIVIC]

mine too.

when i had my d series i turboed it and i had the idle problem with larger injectors but when i adjusted the fuel with the vafc it smoothed out?????

now i have a b18 ls swap 94 in my si hatch and it idles too low then sometimes not always idles up and down! i was told that the throttle position sensor goes bad on them and will cause this but have not spent the 80 bux on trying this. i was also told that any tps would work but havent found any proof of this either so someone must know!

i have heard of alot of people having this issue but noone knows how they fixed it or wont tell!

[SDBCIVIC]

see is it iacv or tps?

[JDMef88]

same thing happened to my on my y8, if you turn your car off, take off neg bat term, and adjust the screw on your throttle body to the left it cuts your idle all the way down and it made my cel go away and my up and down idle...thats my 2 cents...

[EvasiveEF9]

Check your CEL, and check your vacuum hoses...

[vancem3m3]

theres no cel and if i had a vac leak i would have a boost leak also it doesnt do it bad just a little when the heat is on

[scttydb411]

is this on the new motor?

[2ndGen.Teg]

EGR valve mabye?

[blackshine007]

Most of the time when a Honda idles like that, it's more than likely the O2 sensor has failed. The first to do is to take a needle and backprobe it into the wire. Take a multimeter (I have a snap on vantage pro for graphing purposes) and while still plugged in, watch the voltage. A good working O2 sensor still plugged in is gonna try to produce any where from .300 to .700 due to the computer doing the rich/lean switch (basicly for emissions) and you have to be certain that it's switching in that manner to make sure it's not stuck reading too rich or too lean. Another thing you can try is the bench test. Unscrew it and with heat put a bottle of butane on it and be sure to move it around the tip in a circular manner or your destroy it as it will surely burn a hole through the insulator. The O2 sensor should produce when fully hot 1.27 volts and when you take the heat away from it it should drop like a rock. Anything under that and it's no good. Try that and see if it works.

[1flysi]

Does it do it when the motor is hot or cold?