shawnmd

I have a 2003 Civic in which the idle is surging up and own from 750 to 2000 rpm. It also through a code about the PCV valve and Idle air control valve (IACV)(Codes -P0113, P0505 idle air control, P0505 PCV air leakage, P1519 IACV circuit failure and P1457 EVAP control system leak).

I removed the IACV and cleaned it tonight but when I removed the collant lines, I didn't get a drop of coolant spill out- it was dry. The car does have a small coolant leak, could this be causing an air lock and coolant not getting through the IACV? Could that cause issues with idle?
If not, what could all these codes indicate, or are they all separate issues? Do they all point to a vacuum leak?

ezone

The 1457 is a separate issue, most likely. Evap canister system leakage detected. Many different things can cause this code, you can't just replace any old part to fix it. Diag is necessary to get it right.

The P0505 is related to the high idle speed, the PCM can't control it. Maybe the IAC is stuck wide open.
HINT:



Ok, I know this isn't your throttle body. Pull the lid off the air filter box, look in yours and you should see a large hole like that pic. Get the idle surging, then cover the hole with your finger. If the surging quits and the engine idles down, then the IAC is probably stuck open (or unplugged?)


Vacuum leaks can make them surge like that too.

(A rotary type IAC valve does not depend on coolant temperature to control cold fast idle speed. The PCM does that. But the coolant leak still needs fixed.)






The P1519, make sure the IAC valve is plugged in. Circuit failure is an electrical failure; usually wiring, sometimes a bad component (electrically).

P0113 is the IAT sensor, make sure it is plugged in.


Codes can be set when stuff was unplugged with the key turned on or the engine running. Some people like to unplug stuff while the engine is running, that leads to more codes than it should have.

I might suggest clearing the codes, then recheck codes and see what comes back first. Then chase that one.
Rinse and repeat until all codes are addressed.
May take a few drives to reset the evap code.

shawnmd

Thanks ezone. I blocked off what I thought was the IACV port and immediately the car started idling fine. So does this mean it is stuck open and needs to be replaced?

ezone

If it is not setting the P1519 code now, then the IAC is probably stuck wide open.

Try letting it idle and surge, and beat on the metal shell of the IAC with a screwdriver handle or tiny hammer (don't break it!) See if the idle tries to come down as you knock on it.

This usually works when they are physically stuck, but not always.

HTH

tlee808

For this example where IACV seems to be stuck open and you cover port, did you try to remove the electrical connection for the IACV. If you did remove it and and the idle dropped then I would assume it was not stuck open. However it would not make much sense since covering the IACV should have the same effect as unplugging the IACV.