Idle Air Control Valve gone bad?

[dfwhockey17]

I recently threw a CEL and just had it scanned, came up misfires on all cylinders due to a bad Idle Air Check Valve. After letting the car idle rough for a few minutes the CEL started flashing, however after revving the motor the CEL went back to solid. Now, I can drive it and keep the light from flashing by putting the car into neutral and keeping the revs above 1k while stopped as to just not let the car idle. I believe the valve is stuck shut and I am getting too much fuel at idle causing the misfiring. All that being said, does anyone have a part number or know a place to order one from? I am getting ready to do a number if things on the car including the timing belt, fuel filter, steering rack among other things and this is just one more thing to add to the never ending list of fixes...the car is an '04 1.8tq tip with 79k on the clock. Thanks in advance!

-Trent

[old guy]

Hi Trent. I am not aware of an "idle air check valve" on your car. My guess is that you are experience a small vacuum leak from a cracked/split hose somewhere. You will get a flashing CEL when the idle gets really rough. The ECU is monitoring the dwell time between the the individual firing events via the knock sensors and when the events become irregular enough you get the flashing CEL. By holding the revs a little higher you manage to smooth out the RPM's enough to stop the flashing but the light will stay on solid until the ECU doesn't see the causative event for several cycles. Check all your hoses and check valves for a leak somewhere. You may have to pressurize the intake track to find it (boost leak test). The addition of "false air" will mess up your A/F ratio and cause the misfire. Sounds like a small leak since the issue is only at idle.

Good luck!

[dfwhockey17]

Thanks Old Guy, I will check all the hoses/valves and see if anything is loose or broken. What are the most common ones to fail if there are some more prone to failure than the others?

[dfwhockey17]

Well after using the tennis ball method to search for vacuum leaks I found a few cracked/broken fittings that led to my rough idle and misfiring. Thanks to Old Guy for suggesting where to look after the initial scan from the shop diagnosed a bad "idle air check valve" and misfiring on all four cylinders...

The broken pieces (9) and (2) were ordered from genuinevwaudi parts along with numbers (3)(5) and (13) for less than half of what the local dealers wanted...
By the time I get these pieces the timing belt kit I ordered should be here and I can finally tackle that job as well as put in the new steering rack and change out all the fluids. I have a feeling my car and I are going to become real close over the next few weekends...Once again thanks for the help Old Guy!

[FutureStage1]

What is the tennis ball method? Sorry I'm a noob and I'm experiencing the same symptoms in my car.