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Discussion Starter · #1 ·
Good morning all,

My 2.3 is doing some interesting things while at idle. When my HVAC is on, the RPM's will suddenly drop from approximately 650 to 300, almost causing my car to stall. This lasts for about 2 seconds then it returns to normal. It appears to happen when a new load is put on the engine. When I turn my HVAC off completely, the idle is fine. I cleaned my MAF and changed my air filter thinking this was the cause. Any thoughts or checks I should be doing to narrow down the issue?

Thanks for any advice.
 

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Is this with the engine warm or cold?

I wonder if this has something to do with your charging system. If the voltage is too low due to a dying battery or alternator, the spark may not be what it's supposed to be for proper ignition.

Could also be a faulty idle control valve or something. I'm not much of a mechanic though!
 

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Discussion Starter · #3 ·
It typically happens when the engine is warm.

A friend told me to try driving it with the heater set only to the vents and not to the window defrost and see if it happens. He thinks it may have something to do with the AC compressor cycling on and off while in defrost mode.
 

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A similar thing would happen to my old '02 Focus. Went through three alternators with only a temporary fix to the problem. The last time it happened, they considered an issue with the PCM chip.. but soon after that I got my Fusion. Not sure if this would help, but you could try the idle relearning process, which is detailed in your owner's manual.
 

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Discussion Starter · #5 ·
I'll give that a try tonight.

It's so frustrating on these new cars. It's all this computer crap. On my old Aerostar if this happened, I would check and adjust the timing and it was good for another 100,000km.
 

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my old Volvo S40 did this too. I'm fairly sure it's the idle air control. It's like a valve type thing that gets a gunk buildup that can be cleaned out. Did you try that thing with the defrost on and off? Bet you it won't do it when the defrost (A/C) is off. The IAC is having trouble compensating for the additional load on the engine that the AC compressor makes. Your idle will dip also if you hold the power window switches up if the windows are already fully up.
 

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Discussion Starter · #7 ·
Hi Lyonsroar, I was going to try it tonight on my way home. I agree with you, I'm almost certain it won't act up if the defrost is off. Now, really stupid question, where is the idle air control located so I can clean it up.
 

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[quote author=Familia1 link=topic=201797.msg4163646#msg4163646 date=1324415705]
Hi Lyonsroar, I was going to try it tonight on my way home. I agree with you, I'm almost certain it won't act up if the defrost is off. Now, really stupid question, where is the idle air control located so I can clean it up.
[/quote]

I have no idea. On my old S40 it was on the front of the engine and only took two small bolts to remove. Fun fact, it also had FORD stamped on it even though it was a Volvo...
 

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Discussion Starter · #9 ·
Well, I drove all the way home with the defrost off, approximately 90km, without so much as an issue. When I pulled into my driveway I switched on the defrost and the idle dropped and stumbled. Now it's time to search for the IAC.
 

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[quote author=Familia1 link=topic=201797.msg4163703#msg4163703 date=1324424244]
Well, I drove all the way home with the defrost off, approximately 90km, without so much as an issue. When I pulled into my driveway I switched on the defrost and the idle dropped and stumbled. Now it's time to search for the IAC.
[/quote]

Hi familia. :wavey: As ischn23 mentioned, try the "idle and fuel trim strategy" relearn procedure before you go through the trouble of removing and/or replacing parts. It is explained in the Maintenance and Specifications section of the Owners Manual where it discusses replacing the battery (page 231 in mine, but yours may differ).

While it may not cure your issue, it is free and worth a try.

Also, just out of curiosity: have you had your battery disconnected/replaced lately or had your Fusion in a shop for any type of service?

Let us know how you make out and good luck. :cheers:
 

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Discussion Starter · #11 ·
Hi bbf2530,

The car has been in the shop quite a bit lately, but the battery has never been removed.

I'll do the "Idle and Fuel Trim Strategy" tomorrow. Is it better to start the relearn process while the engine is stone cold, or should I drive it for a bit to warm it up, then pull the battery and do the relearn?
 

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[quote author=Familia1 link=topic=201797.msg4163741#msg4163741 date=1324429261]
Hi bbf2530,

The car has been in the shop quite a bit lately, but the battery has never been removed.

I'll do the "Idle and Fuel Trim Strategy" tomorrow. Is it better to start the relearn process while the engine is stone cold, or should I drive it for a bit to warm it up, then pull the battery and do the relearn?
[/quote]

Hi Familia. :wavey: In the case of the instructions for my car, step 1 is to set the parking brake, step 2 is to "Put the gearshift in P (Park), turn off all accessories and start the engine" and step 3 is to let the car warm-up to operating temperature (temp gauge needle reaching normal operating temperature). And in the case of my engine/car, there are 7 steps followed by at least 10 miles of driving. But the process does differ slightly for some engines/model years. Therefore, the best advice I can give is to read and follow the instructions that are listed in your Owners Manual to the letter.

Your Owners Manual will tell you exactly what to do with your car (whether the engine should be warmed or not etc.) and you need to follow the instructions exactly. Do not skip a step or think one step or another is not important. If you don't follow them exactly, it is an exercise in futility. And in this particular case, you do not need to (and I would recommend you do not) "pull the battery" before proceeding to do the relearn procedure. It is not part of the relearn process, it is simply one of the reasons to perform the process.

Also, while you may not think the battery has ever been disconnected (it does not need to be "removed"), it is entirely possible the battery was disconnected on any one of those shop visits. There are many repair procedures which require the battery to be disconnected for safety purposes alone. I have no idea whether it was or was not disconnected, just offering the suggestion that there is a chance it could have been disconnected without your knowledge.

Anyway, let us know how you make out and good luck. :cheers:
 

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It is the idle trim that is off for sure. I have taken the battery out for many reasons and forgot to do that stupid relearn and thats exactly what happens (infact its happening to me right now from me taking off some components and not resetting the components). The shop most likely took off a battery terminal to make sure that electrical damage didn't happen while doing something to the car, its a very common practice. They probably didn't know about the relearn process and now your having that slight problem.
 

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Discussion Starter · #14 ·
Thanks for the info!! I'll do the relean tonight before I head home. I'll give you an update to see if it makes any differennce.
 

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Discussion Starter · #15 ·
Well, I did the relearn this evening before I drove home. It didn't do a thing to my idle issue, but on a positive note, the transmission seems to be shifting smoothly now.

I'm going to check out my Throttle Body this weekend to see if it's gummed up.
 

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Discussion Starter · #18 ·
Hi All,

I sprayed the MAF and put a new air filter in it last weekend.

I have about 212,000km (132,500 miles) on it right now. I usually put a bottle of Lucas Fuel Injector Cleaner in everytime I do an oil change. I changed the plugs, I believe, about a year and a half ago.
 

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[quote author=Familia1 link=topic=201797.msg4164400#msg4164400 date=1324555871]
Hi All,

I sprayed the MAF and put a new air filter in it last weekend.

I have about 212,000km (132,500 miles) on it right now. I usually put a bottle of Lucas Fuel Injector Cleaner in everytime I do an oil change. I changed the plugs, I believe, about a year and a half ago.
[/quote]

Hi Familia. :wavey: Just grasping at straws here with some basic troubleshooting, since internet diagnosis is usually a guessing game at best: You first posted with the issue on the 20th. How long before that did this issue begin and is there absolutely anything you may have done with or to the the car shortly before it began? Even something you don't think would cause a problem? For example, did you have the car in for some sort of service or maintenance at a shop (or do anything yourself) right before the idle issue began, put any additives in the fuel tank, change your regular gas station etc.?

Again, just throwing out ideas that probably will not lead anywhere, since this seems to be connected to the A/C compressor or other HVAC component in one way or another. Sometimes bringing it in for service winds up being the most efficient way to solve a problem.

Keep us updated and good luck. :cheers:
 

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Discussion Starter · #20 ·
Hi bbf2530,

About 2 weeks prior to this issue, I had changed my oil (Pennzoil 5W20 High Mileage) and a bottle of Lucas Fuel Injector Cleaner. I cycle between 2 gas stations depending on where I am in the city. I typically fill up my car twice a week from about the 1/4 tank mark.

I'll see if the mechanic across the parking lot can take a look at it. It's frustrating because it's enough to make the car idle rough at times and make me nervous, but not bad enough to trip a CEL or outright stall. Before this issue, the car ran like a top.
 
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