Is this normal or is there something wrong? It only does it on very long hills, high throttle for low amounts of time it works fine. Thanks

 

Wild Vents maybe...

 

you could have a minor vaccum leak somewhere, otherwise it seems like it could be normal, the vents are vacuum operated, full throttle or close to it results in very little to no vaccum, and defrost is the default for the vents, get a good look at all your vaccum lines and connections.... shut the engine down and instantly listen for any slight hissing noises is the easiest way i have found

 

i'll see if i can hear anything? one thing i noticed is that the 4wd light stays on once shifted out of 4wd then flickers, but the 4wd engages and disengages correctly, engine runs fine at idle, so if not normal it must be a very small leak. just picked the truck up last thursday, aside from this i'm loving it

 

4wd is vaccum operated too, get a look at thoes lines as well, from the engine, to the t-case to the front axle

 

They look fine to me, so do the ones that connect to the vacuum switch on top of the transfer case, 4x4 works great, and this problem only happens when i'm on a long hill, it's 5 speed so i usually just let it put up the hills in 5th gear. so if it only happens then i'm not going to worry about it. i found another forum that said it could also be bad pcv valve or failed check valves, mine is a 98, do you know where all of the check valves are?

 

I just went through this. You're vacuum Check valve is shot. The only place to get an exact fit is Dodge Dealership.. About 10 freakin bucks a pop. Under the hood, on the passenger side, you will see tiny hoses coming down from the back, Ill dig up a pic and post it. The valve is there. Just a sec and ill post one

 

https://dodgeforum.com/forum/2nd-gen...cuum-leak.html There ya go... That explains it.


I also had 4wd light issues.. Eventually the light stopped coming on.. 4wd works fine. So I haven't looked in to that. I did have to fix the fork on my 4wd, but it wasn't related to this..

 

Thanks I appreciate it

 

You bet. Hope it helps.!