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Discussion Starter #1
Hello everyone,

I have a 2007 ZX4 SES. The check engine light came on a few days ago, along with some unusual behavior from the engine. Whenever I turn the key, when the car is cold, the engine immediately revvs up really high, it sounds like I have my foot on the gas, down to the floor.

It goes back to normal when I put it in gear, and drives just fine. It will also go to high idle when I put it in neutral, but only if the engine is cold.

I took it in and had the codes read when I was getting some new tires, but I think the guy at the shop told me the wrong part was bad. He wrote down "Intake Air Control Actuator".

I think he meant Idle Air Control? I couldn't find any trace of "Intake Air Control Actuator" online.

Does this sound like an IAC problem, or could it be something else?
Also, is the IAC hard to replace myself?

Thanks,
 

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Yes, that's the IAC ( idle air control valve ). Not sure what engine you have. But I'm dealing with mine on an '01 with a Zetec engine. It's a huge PITA on mine. Find out what engine you have and go from there.
 

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Captain TMI
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It's the idle air control valve, and as long as it is going down to normal when you put the car in gear, it's probably fine. Do you have a tachometer? If not, then use the electronic odometer trick to see what rpm it is revving to exactly when it's cold. It is normal for the engine to idle high when starting in the cold, and the colder it is, the higher it will go up. Then the idle will drop accordingly over 1 minute. That is to warm the engine up because engines perform more efficiently when warm.

Typically it only revs to about 3k for a few seconds, but hangs out around 2k rpm until warm. Once it's put in gear, it should drop down, and stay down.

Here's the electronic odometer trick:
http://www.focusfanatics.com/howtos/electronicodometer/

You might want to try it some time and count the number of presses, or see what is just before it. The number of presses will be different than listed her on earlier models. Also, right before or after it is the cam position sensor which registers exactly half the engine rpm.

And yes, it's called the idle air control valve on this vehicle, and if anything, it simply needs to be removed and cleaned.
 

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Captain TMI
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OH, BTW, why I say the IAC isn't bad is because the idle acts normal when you are in gear. Another thing you can do, and should be doing as part of routine maintenance, is cleaning the MAF. Before replacing the IAC, I would clean the MAF and reset the A/F ratio like so: The MAF is located on the air intake tube as it goes down into the fender behind the driver's side headlight. 2 torx screws hold it in. It is the only electrical part in the air intake. To unplug it, first slide back the red clip holder, then press on the clip. Then remove it's screws. Don't worry, you can't put it in backwards. Now spray the holes in both sides with spray MAF cleaner. Don't stick the nozzle in the holes or you might damage it. Shake, and give a few minutes in the sun to dry out. Now is a good time for the other part, remove the negative battery terminal. Clean if needed, and re-install the MAF. Reconnect the negative battery terminal after at least 10 mins disconnected. If you want, you can set the odometer to test mode so you can see the engine rpm. Start the engine, but don't touch the accelerator. The engine will idle up, and then settle around 1100 rpm. It will fluctuate slightly for 5 minutes after it settles while the ECU preforms a test. The test will last exactly 5 minutes after the engine is out of cold start/high idle mode. Once the test is finished, the engine rpm will drop, or just let it idle for 7-8 mins. Now the Air/fuel ratio is reset.
 

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Discussion Starter #6
Thanks for the quick replies. Gives me some things to try tomorrow.
I'll probably try cleaning it first, and doing that electronic odometer trick.


No I don't have a tachometer.
And when I say starting up cold, I just mean I haven't turned it on for a few hours. I'm in Central Florida, the engine is never truly 'cold', but it will stay in a high idle for far longer than usual. I've never let it go for more than about 5 seconds, but it shows no signs of coming down until I put it in gear.
 

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OH, BTW, why I say the IAC isn't bad is because the idle acts normal when you are in gear. Another thing you can do, and should be doing as part of routine maintenance, is cleaning the MAF. Before replacing the IAC, I would clean the MAF and reset the A/F ratio like so: The MAF is located on the air intake tube as it goes down into the fender behind the driver's side headlight. 2 torx screws hold it in. It is the only electrical part in the air intake. To unplug it, first slide back the red clip holder, then press on the clip. Then remove it's screws. Don't worry, you can't put it in backwards. Now spray the holes in both sides with spray MAF cleaner. Don't stick the nozzle in the holes or you might damage it. Shake, and give a few minutes in the sun to dry out. Now is a good time for the other part, remove the negative battery terminal. Clean if needed, and re-install the MAF. Reconnect the negative battery terminal after at least 10 mins disconnected. If you want, you can set the odometer to test mode so you can see the engine rpm. Start the engine, but don't touch the accelerator. The engine will idle up, and then settle around 1100 rpm. It will fluctuate slightly for 5 minutes after it settles while the ECU preforms a test. The test will last exactly 5 minutes after the engine is out of cold start/high idle mode. Once the test is finished, the engine rpm will drop, or just let it idle for 7-8 mins. Now the Air/fuel ratio is reset.
This one saved the day for me!! I have a 2005 ZX4, and had I not stumbled across this I probably wouldn’t have stumbled into about 120 more miles per fill-up. Thank you sir!
 
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