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Discussion Starter #1
Hey Y'all,
I'm really at a standstill on this one.
Engine has had random rpm dips at idle. Normally stays aroun 600-700 but will randomly dip below 500 and feel like it's going to stall.

https://youtu.be/WGng_AOjANg

Happens at about 0:08, 0:28 and 0:34. There's no specific pattern to it.

Replaced the PCV valve and hose under the intake manifold with no luck.

I'm not sure what to try next. I can seemingly force this to happen by holding down the power window buttons, but it happens on its own regardless. Any ideas?
 

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Possible vacuum leak elsewhere.

If higher mileage engine even the a/c cycling on can do it if on defrost. Common when they get older.
 

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Discussion Starter #3
I think the valve cover gasket could use a replacement. Would this be enough to cause a vacuum leak? Is there an easy way to diagnose which vacuum line is problematic? I'm not hearing any hissing from the engine compartment.
 

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Discussion Starter #5
When I replaced the PCV I took the throttle body off of the intake manifold and cleaned everything out of it. The problem only seems to be at idle. My next thought was to try new spark plugs and coils, but i wasn't sure if that made sense when the car is running fine with throttle.
 

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I had an issue with mine and believe it or not it was low on refrigerant and it was over cycling the AC system.

Sent from my LG-LS997 using Tapatalk
 

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Discussion Starter #8
I agree that the AC is the likely culprit. However, it's -8 where I'm at, with no 60°+ days in sight. Would I be smart to pull the AC relay until spring? Would there be any issue driving without it.
 

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Discussion Starter #9
Pulled the AC Relay and no changes. Is there another workaround for the time being until the temp increases? My next thought was to replace the plugs, coils and boots just to be sure it isn't a basic preventative maintenance issue. I'm on my third valve cover gasket and there is oil in the plug wells again ?. Here's to hoping the PCV was the main cause of that issue. Back to the main topic, anyone have any other ideas before I jump in?
 

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Discussion Starter #10
I walked around back and it sounds like the Focus is misfiring, but again it's only at idle and sometimes upon acceleration.

https://youtu.be/FHRwC6L-N40

The interesting thing is that the exhaust is pulling in air every time this noise occurs.

Would you assume it's an ignition issue?
 

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Mine is doing the same thing, except mine seems worse than yours is. I still haven't replaced my o2 sensors or EGR valve yet, which may be causing the issue. However, I am 100% sure in my instance that I have a vacuum leak (possibly multiple) due to being able to hear hissing coming from the engine every so often.

Here's a list of things I know that will make it idle worse:

- Turning on the AC
- Turning on the defroster
- Switching from park to drive will temporarily cause an upset (assuming this puts more load on the engine)
- When it's colder outside (20 F or so)

I am taking it to a shop to have someone more knowledgeable than me look at it on Thursday. I don't have a CEL yet.
 

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Discussion Starter #12
Changed the spark plugs, coils, valve cover and gasket. Between making these changes and unplugging, cleaning and replugging everything in the way of the valve cover, I seem to have fixed the problem. Thanks for the help y'all!
 
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