3FE idle issue, not like the rest.

[Spencersieler]

Hey everyone, after 10K miles, I'm deciding to try and fix the idle once and for all.

In my 1992 LC, 269K miles, The thing runs perfect, fires right up, will cruise all day no problem. BUT, when I pull off of the highway or after some fast(er) driving and come to a stop the idle becomes very rough along with oil pressure dropping below the low mark (at least by the gauge, I know they can be inaccurate). As I keep driving at a slower speed the idle gets a little better but still not smooth.

I have done a full tune up and I'm currently running lucas oil stabilizer also.


does this sound similar to anything you have heard of?

 

[jonheld]

Rough idle is almost always attributed to a vacuum leak or unmetered air entering the system.
Check the intake plenum for cracks at the bellows.
Why do you need oil stabilizer? Is your oil unstable?

 

[19LandCrusher92]

Sounds like egr maybe hanging open, you can take it off and clean it, but be prepared can be PIA!!

 

[tacosupreme]

Mine recently had a similar issue and I had a hard time figuring it out. I ignored it for thousands of miles until one day while in the woods 20 miles from pavement it suddenly got much worse. Every time I would put it in reverse it would blubber and die. Luckily I noticed a tear on the bottom of the 2nd intake tube bellows. When I put it in reverse the motor mounts flexed just enough to widen the crack and it would kill the motor. I've been saying for years I could fix anything with duct tape, and for once it was true. Once I got back to town I ordered new intake boots and clamps.

 

[Spencersieler]

thanks for the replies guys, I just replaced the intake hose your talking about, mine was pretty brittle. it didn't really help but hey, i needed it anyways. Ill look into the EGR valve… that kinda makes sense to me. I have also replaced all the vacuum lines at 260K miles

 

[jonheld]

To avoid further speculation please give us a recent maintenance history. How long have you had the issue?
The motor needs to be sealed and any leak will cause a rough idle. Side cover gasket, valve cover gasket, valve cover grommets, oil fill cap gasket, oil dipstick gasket, etc.

 

[Spencersieler]

ever since I have owner the rig, the motor is sealed, I have no leaks.

 

[Spencersieler]

anyone else?