Idle problem after replacing IACV and FITV

I’m having a warm idle problem when the car is warmed up. It jumps from 750 to 1500rpm. When the car is cold on startup the idle jumps to 2000 rpm then to 1500 and lower as car warms up. Soon as car is warmed the idle starts bouncing.

  • Replaced IACV with a clean one. When unplugging the IACV the car idles but of course throws a CEL.
  • Replaced FITV with a good one.
  • When I take intake off, air is being sucked into top throttle body hole but barely any from FITV hole when warm.
  • Putting fingers on both holes in throttle body makes car idle to normal and not dying.
  • All the vacaums are right. But I should go recheck all of them soon as I get up tomorrow.
  • Wondering if the TPS isn’t right. When I unplug TPS connection the car idles, but pretty high though.

Note: I just replaced the clutch and moved around some wires while replacing the clutch, but everything is plugged back in. Also, I have water in the radiator when I drained the radiator while replacing the clutch. Could water in the system cause the issue? Do I need to put coolant and bleed it to fix the idle problem (water in radiator is temp as I was draining and flushing the coolant)?

Also, I’m thinking of getting a new O-ring gasket for the IACV and FITV to see if it’s that.

What could be the problem? I’m pretty stumped and never been this stumped before with an idle problem.

make sure the fitv and iac where replaced correctly and all hoses are are in the same place…runn the car and bleed the coolant for air…leave the bleeder open till you see consistent fluid coming out , then check your radiator level top it off and and let that bleed for a lil and then put the cap back on…if u didnt touch the tps you shudnt have a problem with that sensor… make sure your throttle plate is at the correct opening.i hope this helps good luck

Matt,

  • Very unlikely that your TPS would have anything to do with it unless it’s completely random and unrelated.
  • Running straight water is just fine, it will not cause idle issues. “Coolant” is more important for preventing freezing and preventing corrosion or build up. It can help cooling when compared to water but that should not be thought of as it’s purpose.

First thing I would do is reset the ECU and make sure there is no air in the cooling system, burp the system multiple times if needed. If the idle is normal when it’s cold, then your FITV should be OK. The sole purpose of the FITV is to provide more air to the engine when it’s cold to keep idle up and keep the engine from stalling. Sounds like that’s working just fine. Once it’s warm the IACV takes over. Have you ever adjusted the idle screw before? If it was adjusted previously it may need to be adjusted back. My experience is that the idle adjust screw NEVER needs to be touched. You will pull your hair out trying to find the problem, then adjust the screw to help the problem. But later on you’ll figure out the real problem and need to put the idle adjuster screw back to where it was originally.

It would also be a good idea to replace any o-rings for the FITV and IACV, I doubt they’re the problem, but they’re cheap and if there’s a slight vacuum leak somewhere it could be exacerbating other things.

Fixed it. The vacuum hoses on back of intake manifold were off.

haha and whats the first line i said ???