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Ask Chris (aka- Moose) Your Own Question
Chris (aka- Moose)
Chris (aka- Moose), Technician
Category: Lincoln
Satisfied Customers: 2205
Experience:  16 years experience with Lincoln
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Trying to find a reason why my 08 MKZ runs rough when its

Customer Question

JA: What confuses you?
Customer: Trying to find a reason why my 08 MKZ runs rough when its cool outside. Colder it is outside, worse it gets.
JA: Are you fixing your MKZ yourself? What have you tried so far?
Customer: new plugs, oil, filter, cleaned the MAF sensor. The bottom end rumble/vibration almost disappears when its hot outside. colder it gets, worse it gets.
JA: Does the engine stall right after starting? And what about hesitation or jerking during acceleration?
Customer: no stalling. no hesitation or jerking. just a rumble/vibration. gets slightly better when the engine warms up. but it absolutely tied to the outdoor temperature. On a hot summer day, the engine is very smooth. And Im not referring to the 2 seconds of noise while oil gets pumped to the top of the engine. this it constant.
JA: Anything else you want the mechanic to know before I connect you?
Customer: no
Submitted: 9 months ago.
Category: Lincoln
Expert:  Chris (aka- Moose) replied 9 months ago.

Welcome, I'm Chris (aka Moose) I prefer to work when others don't, I am here around lunch and after dinner till after midnight.

Current miles?

What is the idle speed in park cold and hot?

Rumble/vibration like its running poor or like something inside the engine is making noise?

Once started cold how long must it run to operate trouble free?

What grade oil has been used?

Any warning lights on?

Customer: replied 9 months ago.
current miles is 170K. Probably been doing it for 35K miles. But in the summer it almost completely goes away so I kinda forget about it.
-It does go into high idle when you first start it, as it should. 1000-1100 RPMS or so. After a few minutes, it will go back down to a normal idle speed 600-700rpmsThe rumble vibration is not something loose clanking around. Its the engine."Once started cold how long.........?" It really doesn't get better as the engine heats up. In the summer the problem is so slight, its completely or darn need gone all the time. When the outdoor temperature starts dropping 50 deg, 40 deg, etc.... The problem gets worse. When you cold start on a cold day, the problem will only slightly improve when the engine reaches running temperature.-never anything but Moble 1 or syntech. Never an engine warning light.It gets worse when the engine is under load. Like going up a hill in 1-2 gear. Or when the suspension is loaded. Like a dip(not hard bump)that causes the suspension to compress and release over a 1/2 second period. When the suspension loads you will hear the engine grunt a little more. Not burning oil. Normal gas milage. And normal performance on a hot day. I baby it in the cold because it always sounds like its about to spin a bearing
Customer: replied 9 months ago.
This problem is at least 2 years old. But is at it's worst 6 months of the year. I've run countlesss cans of sea foam and injector cleaner through it. Sea foam has can aerosol can that you spray in to the intake line at high idle that supposed to clean all your valves. I've done that as well as clean the throttlebody
Expert:  Chris (aka- Moose) replied 9 months ago.

Withthe new info, I do not believe I can figure this out not in person to get to the level of answer I expect from myself. I am going to opt out.