I recently replaced by IAC valve due to an engine code and online suggestions. Now that it has been replaced with a new part, it starts surging once it has warmed up. Any suggestions?

 

use carb cleaner to check for a vacuum leak, especially around the IACV. are the vac lines all plugged in properly? did you clean the egr and passages? still throwing codes?

remove the intake air duct, warm the engine up, use your finger to cover the IACV port inside the throat of the throttle body. does the surging stop? if so the IACV could be stuck partially open.

 

currently. I cleaned the original unit and put it back in. So far it is not surging and no engine codes as of yet. I will try your suggestions when the new replacement comes in.

Thanks

 

Wait a minute! If you replaced the IACV it has cooling lines running to it, right? If so, you should bleed the entire cooling system to get rid of air that you introduced into the cooling system when you replaced the part.

 

I have replaced the IACV and bled the air out of the cooling system. It is still surging, I was told to check the fast idle valve, however i am not sure where to find that on the 2.3 vtec engine.

 

Also, no vacuum leaks

 

The F23 does not have separate IAC and FIT valves. They are combined into one valve, known as the rotary air control valve. I am going to assume that you have been working on this valve.

After you cleaned and installed the RAC valve and bled the cooling system did you rest the ECU and do the idle rest/learn procedure. This will allow the ECU to adjust to the cleaned RAC valve and adjust it accordingly. If the RAC was clogged over time the ECU will adjust the valve opening dependent on the response from the PGM-FI sensors. Once you cleaned out the valve it may be opening the valve the same amount and allowing more air, causing the idle fluctuation.

 

Tried the reset and still no dice.

 

OK so to get this straight. you are currently running the original rotary air control valve (IAC) located on the back side of the intake manifold, You just removed it, cleaned it and put it back on?

What was the specific OBD (engine) code and issue that pointed you toward the RAC (IAC) needing attention?

 

P0505, I replaced the IAC valve when the new one came in. The old one ran fine for a day after cleaning then started surging again and threw the code P0505 idle air control. I also checked for a vacuum leak with non found. I have also bled the coolant to remove any air pockets. I also tried the ECM relearning option...all to no avail.

 

P0505 is a circuit failure error. Therefor cleaning it or replacing it may not solve your issue. Where you have a new one, it seems that your problem is with the wire harness or connector. You will need to test the power and ground wires to the RAC valve to see if there are any shorts. As well ensure that the connector is well sealed, the pins are tight and free of dirt and corrosion.