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Discussion Starter #1
...The Sable, not me! It seems that cold starts are beginning to run rough when the idle first drops below 1000 RPM. Definitely a misfire. Once you start driving it, or get the RPMs above 1000, it runs fine. I still need to hook up the OBDII scanner. I haven't pulled the IAC off to check it out yet either.

Some more chores for the weekend, I guess.
 

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I'm cranky in the morning.....
I am cranky all the time but somewhat less since getting my garage open to use after ~14 years of storing junk. Just in time: struts, sway arm links, and tension strut arm donuts replaced. Trial run tomorrow. One spring broke, other very rusty and ready to break. Ride height = 27 3/4" now. Ready for winter. :D

Lincoln going inside before the next frost.

Garage stuff, still need couple of trips to Salvation Army thrift store to give away baby and small kid stuff.

-chart-
 

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Discussion Starter #4
Had the OBDII scanner on this morning. Total misfire count was increasing, but no specific cylinders were indicated as misfiring. No codes either. So, it's playing "hard to get". I guess I should pull the IAC and take a look at it.
 

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Discussion Starter #6
Pulled the IAC off last night. A little dirty, but not gunked up by any means. A few years ago when I replaced the ignition coils, I replaced all 3 on the rear bank and one on the front (only bought 4). So, there is an OEM Motorcraft coil and a noname coil in the front. I have a couple of spares. Maybe I'll swap out the two older ones and see if anything changes.
 

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Discussion Starter #7
Minor vacuum leak? Lazy PCV or hose?
Can't say on the vacuum leak. It only does it after starting up and the idle speed first drops down below 1K RPMs. The rest of the time it idles without any problems. It's almost like the idle speed is dropping too soon.

The PVC and hose were replaced a couple of years ago.
 

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My '00 Tec wagon was rough on a cold start idle, got to the point of hardly running until it warmed up , idle fine after warm up to operating temp. .
Intake gaskets were the problem, once plastic heated up and expanded it sealed the leaks and ran fine. No matter what I sprayed around them could I pick up those leaks. It made me crazy after checking everything else multiple times.
 

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...The Sable, not me! It seems that cold starts are beginning to run rough when the idle first drops below 1000 RPM. Definitely a misfire. Once you start driving it, or get the RPMs above 1000, it runs fine. I still need to hook up the OBDII scanner. I haven't pulled the IAC off to check it out yet either.

Some more chores for the weekend, I guess.
It's time of year for the gasoline blend to change so you can expect some transition but you seem to have more than that.

Best of luck and keep us informed.

-chart-
 

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Discussion Starter #12
Not a fuel composition issue. It's had the problem for a couple of years - summer/winter were no different. Just more common now. Used to be a warm start issue only. Now, it's becoming a cold start issue as well. I start the car. It runs fine in fast idle. As soon as the idle drops below 1K RPMs, it might start to run rough. Sometimes revving it up will clear it out. If I start the car and just drive away, it runs fine.
 

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It's time of year for the gasoline blend to change so you can expect some transition but you seem to have more than that.

Best of luck and keep us informed.

-chart-
I very much notice this here. Very different starting on the 03 at certain temperatures with winter vs summer fuel.
 

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Discussion Starter #14
I replaced the last OEM Motorcraft coil with a spare coil. The problem didn't change. So, I'll swap out the last "no-name" coil and see what happens.

It seems like it might be dropping down to a slow idle too fast. At 40 deg, it starts at about a 1300 RPM idle. It stays there for about a minute. Then, it drops down to about 1K RPM and settles down to about 700-800 RPM after about another 15-20 sec.
 

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I replaced the last OEM Motorcraft coil with a spare coil. The problem didn't change. So, I'll swap out the last "no-name" coil and see what happens.

It seems like it might be dropping down to a slow idle too fast. At 40 deg, it starts at about a 1300 RPM idle. It stays there for about a minute. Then, it drops down to about 1K RPM and settles down to about 700-800 RPM after about another 15-20 sec.
Both mine drop quicker than that. '03 DOHC's.

-chart-
 

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Discussion Starter #17
I noticed that when it's colder and it stays at fast idle longer, it doesn't have the issue when the idle drops down. Weird.
 

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Discussion Starter #18
Well, the crankiness has turned into downright bitchiness. This morning, 17 deg out. Car starts up fine and immediately drops to a slow idle (700-800 RPM). Rough running, almost stalling. Kick the idle up to 1000 RPMs or higher, everything is fine. After driving a couple of miles, it's fine. The idle drops before it starts running bad. So, the poor running is an effect, and not the cause.

Maybe the IAC is going? It's not dirty. No CELs. No OBDII fault codes.
 

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How is your coolant level? Is it dropping very slowly over a month? I had a rough idle on cold starts with my one 2001 which I believe that it is being caused by a little coolant leaking into #1 cylinder from a head gasket or crack. The car has 170K miles and is going to have a trip to the scrap yard this coming summer. I would get the rough idle and misfire code on that cylinder when the car sat for 18 plus hours, but not always. I added a bottle of head gasket sealer and problem has disappeared for months now. I know it is snake oil but I wanted the car to make it through the winter and spring. The car has a salvage title so it is not worth very much.

I thought you posted some coolant loss in a previous thread.
 
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