Idle Air Control Valves - Not all Equal!

Recently I was chasing an engine idle problem with my 2002 Focus ZX3. You can read all about it here:

This car comes with the 2.0L "Blacktop" DOHC Zetec 16v engine.

During my adventures trying to diagnose and fix my idle problem, I ended up replacing the Idle Air Control valve 3 times. Before the last IAC went into the car, I took pictures of all the IAC valves I had used and I would like to share those pictures with you now.

First an overview, from left to right: Ford Factory equipment, Oreilly/BWD, Delphi

*Note: the BWD part (center) has a gasket just like the Delphi. You can't see it very well in this image as it was affixed to the mating surface with permatex to facilitate installation. The Ford factory part uses the double o-ring pictured.

Now let's get to the interesting stuff.

First a detail shot of the inside of the Ford original equipment part:

Now it is difficult to make out in that picture, but you can see the valve plunger cup through the orifice on the right and nothing in the left orifice.

Now for the Oreilly/BWD part:

You can see the same plunger cup in the right orifice, but you can also see the plunger shaft extends into the left orifice and there is a spring on the shaft extension. The factory part does not have this shaft extension or the spring.

And finally the Delphi part:

Sorry that this one is flipped the opposite direction, but you can see the plunger cup like the factory IAC, and NO shaft extension or spring, again like the factory part.
You might also notice that the casting marks are identical to the factory Ford part (with the exception of the batch number mark).

One final comparison shot:

From Left to Right: Oreilly/BWD, Ford Factory, Delphi

Details to note in this picture: The casting and solenoid cylinder on the Delphi part is IDENTICAL to the Ford Factory part, the BWD part has a slightly different casting and the solenoid cylinder is slightly longer.

Now, the crux of this is that my car never ran quite right with the Oreilly/BWD part installed, but as soon as I installed the Delphi part, it ran Flawlessly, just as it had with the factory ford part.

Additionally, I had a chance to look at an IAC valve from Napa autoparts, and it is the EXACT same part as the Oreilly/BWD, it just comes in a Napa box. Same price, same casting/housing, same shaft extension with spring.

Price Breakdown:
Motorcraft Brand (part CX1775): $125 (
Oreilly/BWD/Napa: $78 (O'Reilly Auto Parts)
Delphi (part CV10102): $60 (

Final verdict? From this experience and past experiences with this car, I've learned that it is very temperamental when it comes to replacement parts, you have to get the right part. Just because something is close, or just because an auto parts store says it will work, doesn't mean it will work properly.

For anyone who has a Mk1 Focus with the 2.0L DOHC "blacktop" Zetec and needs to replace their Idle Air Control valve, I would recommend buying either the Motorcraft part or the Delphi. I would avoid a Napa/Oreilly/BWD part completely!

Interesting. My wagon has a BWD part and even with a tune I still occasionally have idle issues. Mainly after driving it hard. Perhaps I should look into swapping it out. Too bad I already spent the money😭

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