Slight idle change when spraying around the 90 where the booster line runs against the fire wall to the plenum or back to booster. Guess I will order one of those

 

They aren't expensive (~$15 maybe), but why not try a little electrical/duct tape? Either to confirm the diagnosis or as a permanent remedy.

 

I have a broken bolt on the exhaust manifold as well. In a previous thread, one suggestion was to put two nuts on the bolt and using the outboard one as stop, wrench out the bolt. I am missing just the head, I think the PO's mechanic tore it off, but since the spacer was missing as well, there was plenty of thread to get the nuts on. Little cold here in CT to fool with this now, but on the list for spring. I also read away from here, about forcing a nut on and then a quick spot weld to hold it enough to back it out. No matter what you do, lots of PB Blaster!

 

New line came in today. Easy enough to install, but it looks like the seal at the upper plenum isnt tight enough as the issue remains. when spraying the area the idle increases every time. I ordered a new seal with the hose but wasnt able to get the old one out and I didnt want to destroy it and be without a vehicle.

How do you remove the plenum seal where the booster line secures?

 

To remove the line hold the plastic ring flush and pull the line out. To get that fitting out you have to hold the intake butterfly open and punch it from the inside with something long... I used a socket extension.

I hate that fitting. Mine has always leaked, even after I replaced it. It now has duct tape on it.

 

Given how that fitting works I'm not surprised there is a small amount of leakage there, but I'd be surprised if it was enough to cause the problems your truck is having. Who knows?

Again, you could try wrapping the whole fitting with some black electrical tape. Or maybe wrap just the end of the vac pipe (the part that sits inside the upper intake/plenum) to shim it and perhaps provide for a better seal. Or you could do what I did years ago (linked below). I can assure you there was no leakage with this setup.

https://landroverforums.com/forum/di...49/#post255794

http://legacy.discoweb.org/forums/sh...met#post877477

 

If you have the new fitting you could just swap over the 'O' ring and save having to fit the new part.

I know from experience that it is a bit of a PITA to remove the old one and the only reason I did it was to do a 'How to' for an other forum, I'd give you a URL for it, but because the site I have the photos on has gone down, pretty much permanently, I won't because it's useless without the photos.

 

There is a YouTube video on it somewhere.

Really the best solution is to thread the hole for a brass barb fitting from Lowes and about 3 inches of vacuum hose, and get rid of the plastic piece of poo. I put a barb fitting in the inlet right behind it but it was already threaded.

That and the location of our coils are the two worst design features in the engine bay. I am feeling sympathy for the OP because I have been there and done that more than once.

 

New booster line installed. Old one broke in half while removing and fell into upper plenum. Had the joy of removing that, again. Everything seems tight but problem remains and actually seems worse. Could be the warmer temps though, it always seemed to do better cooler than warmer. Looking at the large vacuum line running on the fire wall to a small plenum and then from the connection to the rear of the truck on the passenger side.
Also think their is another electrical gremlin as none of the windshield wipers or heated seats are working. I dont think the 12v outlet/cig lighter or the nav on the rear view mirror is working either. All fuses I can find are good. Maybe a ground, but prob not related to missfires/idle issue.....

 

Are you sure it isn't electrical? Is the engine ground strap secure and the nut and bolt tight? Also there are ground wires (bright green on mine) exiting the back of the upper intake that are usually bolted to the bottom bolts of the coils. They are part of the injector harness. You should be able to barely see them with a flashlight if you hold your head just so.

When the weather changes vacuum leaks can sometimes get better and worse, if they are small.