Ha! It wasn't you who threw the monkey wrench . . . it was me when I started taking a good look at what's involved in a plug change Looks like a set of intake manifold o-rings will be needed, at least.

Not that I expected it to be ez, but this is going to be worse than my F150!

At least cleaned the MAF today, so assuming that did no good (check in the AM), a code-read is the next step.

Hey, thanks for the heads-up on the injectors; I usually clean those on my vehicles by this many miles, so that would have been on a to-do list at some point, altho I didn't think they were a factor with this issue.

Neal

 

Neal, sorry I told you a price for the IAC valve that was different than what you found. The Ford part at AZ is 43.99 and like you found out for the Mercury, $134.99. Interesting the part is built a bit different, looks like the same connecting plug, can't imagine the parts aren't interchangeable, but if your not experiencing the problem now, may be something else. You can take your IAC valve off and clean it too. It does get dirty.

Since your last start up it was 65 degrees, It sounds like you haven't had the problem since the last start up that was in the low 40's. Seems you may have to wait until the temp is back in the 40's to see if you get the same symptom. So it would not hurt to just take your IAC valve off and clean it. It has 2 cambers separated by a valve that opens and closes at start up, it can get a soot type build up on it. Just used something like your MAF cleaner spray and a small brush to clean it out, it may be just getting stuck at colder temps.

I might hold off on the plugs too, I changed mine when I had a lower intake manifold leak last year at 127,000 miles and except for a slightly larger gap, they looked brand new. The rear bank are a pain because you do have to remove the intake manifold to get to them. But..... If you were to do that I would replace all the gaskets on the intake manifold (two sets) and all 3 of your rear ignition coils, because at some point there is a chance somewhere down the road one or more may go out.....But then your talking about spending money, that may not solve an immediate problem. So if it was me I would not go there at this time.

If your not getting a trouble light, probably won't be any codes to read, but since you can get it done free, see if there is anything stored there.


I went through this hold thing with rough idle last year, but it wasn't just at start up, but it was worse at start up. I went through this whole process of changing sensors, trying this, doing that, and spent more money than what I wanted to, turned out to be less than 20 dollars in parts, in my case lower intake manifold gaskets. So, through my experience, and what some other folks have gone though, don't just start throwing money at the problem, unless you got a lot just laying around $$$ and your bored ;o) Let us know the next time it happens, and what the temp was, and if it is a wet damp morning, or a dry morning.

The thing to remember is, at some point you will remedy the problem, so if you can handle a little inconvenience if and when does happen again, you may find the answers here without having to go spend and arm and leg on it. Some really great folks on here, it's one of those few sites where everyone is here to help, and very respectful of everyone else!

Take Care!

Scott

 

Scott,

Wow - double the price for a Merc part. . . I guess that's because they are so rare?

I probably wasn't clear on the symptom vs. ambient temp. The degree of rough idle is temp dependent, but still present even in the 60's.

Definitely, I will give cleaning the IAC a try today and post back as to whether that makes a difference.

Also, I have an OBD reader on my laptop, with a connector. I just haven't used that in quite some time so will have to review the use & download some updates, probably. But, it could show me something even if there are no codes. (This program is pretty neat, BTW - you can plug it in and drive around, recording what's happening, and then play it back later to look for abnormalities.)

Thanks,
Neal

 

Hey Neal,

Started looking parts between my 01 Escape and your 05 Mariner, and they changed something in the IAC, because from 04 to 08 that part for yours is the same for various Escapes in that year range. So it's not just a Mercury thing. O'Reilly has the best price and they could order it for you, not even widely carried in the Metroplex, only one store had it. If you fine that to be your problem.

That's pretty cool what you can do with your laptop, for sure!!!

Scott

 

After removing and cleaning the IAC yesterday as suggested by Scott, I fired the Mariner up this AM when the temp had dropped (cold front passed thru yesterday afternoon). Still not really "cold" in an insulated garage in TX, but cool at least. (Could have parked it outdoors overnight, but since I spent 2+ hours detailing it yesterday, I didn't get too excited about that. The most pampered Mariner in the world. . .)

The cold idle seemed much smoother than it has been, pretty much back to normal.

Will continue to monitor, but this result at least leads me to believe that if the issue returns, the IAC is certainly the culprit. (As several of you of course advised in the first place!)

Didn't get to read codes, since the connector cable I have is not compatible with '05's. Not sure when a change occurred, but I have to spring for a new cable ($140) to be able to connect to the vehicle's computer(s) - and newer vehicles as well. (I originally bought the connector in 1999.) Worth it, given what other less-capable readers cost, or what it runs to have a repair shop read 'em.

Thanks much to all who took time to share your knowledge.

Neal

 

Hey Neal,

That's great news, if you get a chance give us an update in a week or so, after you have had several cold, or garage cool start ups. It's always nice to not have to spend hard earned money to fix something that a little elbow grease and the right knowledge can take care of instead! I still baby my 01, even with 145,000 miles on it, no one believes it's now 10 years old. I still think it's one of the most fun to drive, versatile SUVs on the market for the price you pay. I'm sure a Porsche Cayenne Turbo is a better vehicle and a blast to drive, I could even get one.....but I would have to live in it ;o)

Take Care!

Scott