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Discussion Starter · #1 ·
I am sure this has been posted before, but I can't find it. My car has been having a problem with rough idling then occasionally dying. I have had a tune up, and mechanics have no diagnoses for the problem. There is no CEL at all.
Has anyone else had this problem?
 

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Hatch Nation #136
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Do your headlights dim when you pull up to a stop?

Have you done your fuel filter recently?

Any modifications to the car?

Any other strange things?

Loss of fuel economy?
 

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Discussion Starter · #3 ·
I haven't noticed anything with the headlights

I haven't done my fuel filter.

no mods.

nothing strange just idles funny I heard someone say it could be IAC valve,

fuel economy has been roughly the same maybe a slight loss.
 

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Hatch Nation #136
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Start cheap and change the fuel filter, it probably is due anyway.
 

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DTC P0606
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^ This and search on this forum for "PCV hose". The hose can become brittle or collapse with age/heat causing idling problems by creating a vacuum leak after the MAF. Common on higher mileage cars. Easy DIY replacement.
 

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Discussion Starter · #8 ·
Awesome thank you for the info I'll keep y'all updated on what happens. I want it to run better and then start moding.
 

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Discussion Starter · #9 ·
So I replaced the fuel filter Saturday. That seems to have made the idling better. It is rough sometimes, but not as frequent as before. I think I'm going to try the DPFE next
 

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Discussion Starter · #11 ·
oh really ok then I'm out of ideas my hoses look good they dont look brittle or cracked or anything.


maybe there is just a whole lot of built up raw power in my little foci that is just waiting for the light to turn green.
 

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Find that specific hose- the PCV line- then start the engine. Feel the hose, and you'll likely find that it's collapsed if BCZX3 is correct. I'll have to side with him.

This goes back to a routine maintenance problem. PCV valves should be inspected periodically, and after 10 years- all rubber lines are suspect for failure. In many cases this particular line looks good, but under high vacuum at idle the weak rubber collapses preventing the PCV from doing it's job. This means more air is flowing past the IAC making for a leaner mix. Old carb heads might remember- lean = lower idle, rich = higher idle.

When it comes to engine running problems, for the DIY diagnostic, you really have to make sure that all your routine maintenance has been double checked or performed. Remove the plugs- clean them, replace the wires if lifetime warranty ($0), clean the MAF, check/replace the air cleaner, check the PCV (remove the PCV line from the manifold, and blow into it, you should feel resistance, check for collapsing at idle). After all that, then you can say you have some sort of an issue that might require replacement of a part- in your case the IACV which doesn't give a DTC or CEL if it fails. Things like the DPFE or EGR will give codes, although some of those can be taken with a grain of salt because a bad O2 sensor will cause codes indicating EGR issues. There's still a bit of diagnosing needed- ESPECIALLY when taking the advice of someone online who has never heard the car run or seen it in person. We're just making educated guesses after all.
 
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Hey Wrightfocus - sorry to jump in on this but figured I'd throw in my two cents.

I did have a question for 'Whynot...' - when replacing the PCV - do you recommend a Motorcraft (Ford OEM) PCV valve or are aftermarket ones OK? Does it have to be OEM?

Also, I got a CEL (P1506 if I remember correctly) on my ZTS ('00 Auto) awhile back that said it was either a faulty IAC or Vacuum leak. Replaced the IAC and the rough idle was back in a few hours and CEL came back on a few weeks later. Same code.

I am still trying to fix mine. All hoses look good (newer, not collapsing, etc). Wondering if a non-OEM PCV could cause the issue. I've replaced lots of other parts with no luck.

Good luck. If the PCV fixes my issue I'll be sure and let ya know.
 

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Discussion Starter · #15 ·
Yeah man that would be nice. I don't know anything about the codes on yours. Mine isn't throwig any. I did check my PCV hose and it seems fairly new it has the heat shield on it. The originals didnt have that from what I have researched, so I don't think it's the PCV hose or valve on mine I replaced the valve less than a year ago. So I'm lost with why I'm having the rough idle problem it is not as often as it was since I replaced the fuel filter, but it is deffinately still there.
 
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Wrightfocus - wanted to let you know I installed the OEM Ford PCV on my car and it didn't seem to help much, if any. I was hoping that was it. I did notice today my loopy idle is worse when the radiator fan kicks on and smooths out (some) when it turns off.

Now i'm wondering if there is some sensor or electrical plug for the radiator fan that is causing it...
 
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