Very rough idle on 97 5.0l found!!!!

[NoogaX]

Wanted to share my experiencce with every one. My X was running fine when parked the other night and the next morning would not idle worth a flip. Ran fine if I kept the gas to it but just would not idle. Changed the IAC and no difference. Started looking at wires, plugs and vacuum lines when I found a large vacuum tap cap laying under my intake manifold on the driver's side. Got to looking a little more (like standing on my head) and found a large tube behind the steel lines on the valve covers just the right size for the cap. Tube was part of a "T" that was screwed into the underside of the manifold. Put the cap on and no more rough idle. Didn't have time to follow the other end of the "T" (which had a hose on it) to see where it went but will soon. Cap was very loose so I put a small tie wrap around it and pulled it tight. Sarted the X and what a difference! Idle is silky smooth and the old girl runs like a new one. Guess this cap has been getting loose for some time and finally gave up the ghost.

Don't know if this will help any one else but wanted to give back a little for all I have gotten out of this site. Just for the records my X is a 97 Limited AWD with a 5.0L about 167K and I am getting about 18MPG around town.

 

[JoeMahma]

Wanted to share my experiencce with every one. My X was running fine when parked the other night and the next morning would not idle worth a flip. Ran fine if I kept the gas to it but just would not idle. Changed the IAC and no difference. Started looking at wires, plugs and vacuum lines when I found a large vacuum tap cap laying under my intake manifold on the driver's side. Got to looking a little more (like standing on my head) and found a large tube behind the steel lines on the valve covers just the right size for the cap. Tube was part of a "T" that was screwed into the underside of the manifold. Put the cap on and no more rough idle. Didn't have time to follow the other end of the "T" (which had a hose on it) to see where it went but will soon. Cap was very loose so I put a small tie wrap around it and pulled it tight. Sarted the X and what a difference! Idle is silky smooth and the old girl runs like a new one. Guess this cap has been getting loose for some time and finally gave up the ghost.

Don't know if this will help any one else but wanted to give back a little for all I have gotten out of this site. Just for the records my X is a 97 Limited AWD with a 5.0L about 167K and I am getting about 18MPG around town.

Right on! Glad you got her fixed.

 

[Tom Balzen]

1997 Explorer rough idle at start.

My 97 Explorer, 4.0L SOHC, only 66,000 miles began to have a rough idle problem at start up in cool or cold conditions about a year ago. Problems went away after engine warmed up. Not much help on the web. Tried several things, looking for vacuum leaks, replacing some components etc. Finally traced it down to a vacuum leak in the lower intake manifold, by replacing the gaskets.
The intake manifold consists of two plastic parts, with O-ring style custom gasket between the two parts and between the lower part and the aluminum heads. When I removed the lower part, the six gaskets were found to be hard, stiff, and compressed. The color was slightly greenish. I replaced them with Felpro gaskets which are silicone rubber (I believe) and red in color. This solved the problem. We will see how they age out.
Taking off the upper part is the trick, lots of hoses and things to get in the way. I had to disconnect the cable to the PCM and get out of the way inorder to get to the rear screws on the upper half.
When you put it together, get your torque wrench out. A quarter inch drive torque wrench with sockets (metric) and extensions are all that is required. The screws from the upper are into lower plastic part so you don't want to strip them. The screws (small bolts) for the lower part are into the aluminum head, again you don't want to strip them. The Haynes manual has the torque requirements.

 

[CAPTAIN ZERO]

Right on! Glad you got her fixed.

Thank you so much for the post I have a 97 X I just got rough idle I will check that its posts like this that are worth there weight in Precious metals.