so ive been having this idle issue since i picked up the car 11/11. car is a 98 civic hatch used to be b16 now gsr. car runs fine when i come to a stop the idle stays at 2 and once the car is completely stopped it goes down to 6-900. sometimes it will just stay at 2k if i turn it off then back on the idle is fine. no cel. mods are bc springs and ret skunk 2 manifold and 70mm tb tri y headers straight piping.

 

check the codes first and foremost. always

 

clean the fast idle valve, below the throttle body. theres a diy on here somewhere

 

check for a vacuum leak, especially if you have after market throttle body and intake manifold check the gasket between the 2 might be leaking, if not idle air control valve should be the next issue

 

Have to agree. Had same problem on my 93 'teg. Was told by many people that the surging idle or revving up and down was the i.a.c.v. or the t.p.s. After checking my whole intake, turned out the plunger/screw inside the fast idle thermo valve had come unscrewed... completely. Simply screw it back in (all the way) then back it one or two turns, and re-install.

When unscrewed too far, the valve inside the FITV cannot close the throttle bypass (aids in cold start-up...keeps rpsm up for first minute) and too much air continues to flow around the butterfly after warm-up causing perpetual cold start idle speed. When the plunger comes completely unscrewed in the FITV, the engine will surge and cut rpms at idle. If you're driving a honda or acura, usually this means that untill you fix it, every jock at a traffic light who pulls up to you will think you're trying to race. Annoying.

 

he probably doesn't have a fitv.
checking codes will give direction for a symptom that has several possibilities. if no codes, i'd check for vac leaks using starter fluid

 

My bad. Def could be vacuum leak. Should not have a FITV.

 

i dont have a fitv no codes either ive checked for leaks using stater fluid nada. its not a flacuate idle it just does it sometimes when it does stays stuck at 2k i just turn it off and back on and its ok for a good while or the rest of my trip

 

tried checking/cleaning the iacv? also, have you tried adjusting idle?

 

i cleaned it once before ill give it another try. the idle is good when it comes down or i turn the car off then back on

 

try seeing where the idle sits with the iacv disconnected, as if you were adjusting.

 

check the throttle cable, I know my friend was having that problem with his and it ended up being the throttle cable.