Idle Problem need some advice

[sman83]

I did a search on the forums but I did not find an answer that best fit my question.

I am having a idling problem. When I start my 1999 Mountaineer(V8, AWD) It will idle up and down from 800-1200rpms but after a few minutes of driving it idles back to normal 600-700rpm.

I replaced the IAC about 9 months ago, cleaned the MAF, changed the air filter all around 9 months ago. I am up to date on the maintenance.

There is no check engine light on and nothing abnormal that I could tell besides the high idle at start.

The fuel filter has not been changed since the car was made back in 1999. Could this be a problem? I was going to change it for peace of mind.

Thanks in advance for any advice !

 

[Tbars4]

if you have gone thru and cleaned everthing as in the other threads, there are 2 things i would look at...first, a fuel filter, when was the last time it was changed, when it was new??? 2nd, and more to what you are describing, vacuum lines...if one is cracked it will take a full vacuum to close up...if you pull a vacuum line your rpms go up...i routinely check and replace all vacuum lines as needed as they tend to go out when it gets really hot and really cold...

 

[sman83]

Great suggestions..I will check the vacuum lines ASAP, as it has gotten cold when I changed the IAC and extremely hot now.. and the the fuel filter shouldn't be too hard to replace so I will grab one today or tomorrow..

Thanks !

 

[gijoecam]

Sounds like the typical leaky lower intake manifold gaskets that would have been replaced with the 00M12 cam chain tensioner service (if it was done). Run a search and you'll find TONS of info.

-Joe

 

[manaen]

Sounds like the typical leaky lower intake manifold gaskets that would have been replaced with the 00M12 cam chain tensioner service (if it was done). Run a search and you'll find TONS of info.

-Joe

That only applies to the SOHC motor not the 5.0 V8

Not that you still couldn't have a leaky intake gasket, I'm just referring to 00M12

 

[gijoecam]

Aack... missed the V-8 part of the post.

{gijoecam dons dunce cap and faces the corner.... again}

Nevermind....