IAC question

[T4Rscott]

Hi to all,

I recently did my valve cover gaskets and all of the intake gaskets.

Now I have the dreaded high idle. I made sure the TB and IAC are clean. All of the vacuum hoses have been tested for leaks. I also disconnected the battery to reset the ECU. When cold, it starts as normal. After it is warm, it will come to rest at about 975 rpms, according to my OBDII scanner. If I shut it off, then immediately start it, it will go to about 780, then slowly climb back to the 975ish rpms.

Should I wait a little longer to see if the ECU will re-learn the parameters, or should I source a new IAC? Also, I noticed on the end opposite the plug, there’s a metal plate with two screws. Is it possible to adjust the travel on the valve itself?

I appreciate any and all input!

Thanks,
Scott

 

[Vooryjoni]

I also have an idle issue but mine is idling too low and stalling. How did you manage to clean the IAC? I was quoted at $700 for an OEM IAC plus labor at the dealer.

 

[pluton]

Did you check that the throttle butterfly closes all the way? The reason I ask is because you can buy the entire throttle body, including (last I checked) IAC valve and throttle position sensor for between $500 and $600. That's what I replaced on mine (the butterfly wouldn't close all the way) when I had an even higher idle than you have: It was running about 1200 RPM when fully warmed up.

 

[T4Rscott]

I also have an idle issue but mine is idling too low and stalling. How did you manage to clean the IAC? I was quoted at $700 for an OEM IAC plus labor at the dealer.

It unbolts from the bottom of the throttle body. I then used throttle body cleaner.

 

[T4Rscott]

Did you check that the throttle butterfly closes all the way? The reason I ask is because you can buy the entire throttle body, including (last I checked) IAC valve and throttle position sensor for between $500 and $600. That's what I replaced on mine (the butterfly wouldn't close all the way) when I had an even higher idle than you have: It was running about 1200 RPM when fully warmed up.

It looks as though it’s closed all the way. I suspect it’s the IAC because the part that closes doesn’t have the tightness it used to. I can’t imagine the throttle body going bad.

 

[LittleCaesar]

Pull it off, clean it and the throttle body well and reassemble. Be careful of those brass screws. Make sure to have a new gasket on hand.

 

[baja1]

without even removing it just pop off the coil exposing the armature it'll look like a black knob. rotate it back and forth and should turn freely, it will now act like a idle control. after setting the idle I dabbed a little epoxy on it to keep it in place and I honestly couldn't detect the difference. leave the removed coil plugged in and it won't throw a code!

 

[T4Rscott]

without even removing it just pop off the coil exposing the armature it'll look like a black knob. rotate it back and forth and should turn freely, it will now act like a idle control. after setting the idle I dabbed a little epoxy on it to keep it in place and I honestly couldn't detect the difference. leave the removed coil plugged in and it won't throw a code!

Not sure I want to do that when I can buy a new one for 60. When you say remove the armature, you mean the part the harness plugs into? What keeps the engine at the correct idle?

 

[jacked_72]

97 6cyl P0505 comes on immediately

I'm posting in this thread because I don't have permissions to start a new thread.

I have a 97 4Runner with the 6 cylinder. It started idling low and threw a P0505 (Idle control circuit) code. Idle was 500 rpm and frequently would stall out when cold. I've replaced the IAC, checked all hoses, replaced the TPS, cleaned the MAF and still get the P0505 almost immediately after clearing the light. I got a used TB from Ebay and it runs the vehicle and a higher idle (around 1100) and it will drop the idle below 900 with the AC on. All the IACs ohm out OK per the FSM. If I goose the throttle, the idle initially drops but then creeps back up. There are no other codes beyond the P0505.

I figure the used IAC from ebay is dirty (I didn't clean it like my old one) and I'm guessing that is why it idles higher. The thing that is baffling me is the code immediately setting. I have battery voltage to the middle pin of the IAC connector, so it is getting voltage. I've not checked the voltage at the ECM for the other two wires in the connector. P0505 is supposed to be a two trip code, so the fact that it comes back immediately after clearing is pointing me to a broken wire or ECU fault.

I'm looking for input. I've run through everything the FSM says it could be, but if anyone has run into this before I'd be interested in hearing any potential solutions.