So if you look at the TB right above the IACV there is a vacuum port...well, it really isn't a vacuum port, but it looks like one. The hose connected to it goes to the Valve cover. It is part of the PCV system. The insert that fits in the TB that the hose pushes onto is loose. As in, you pull on the hose gently and the insert pulls out of the TB. Being part of the PCV system, I haven't worried about it. But I can't help but wonder if some of my problems stem from that insert being loose in the TB. What are your thoughts?

Maybe I should just JB weld it in place....

 

Red Loc-Tite works really well to hold that litte piece of tubing in place.

 

That would create another vacumn leak if it were loose would it not?

So I was looking closely at mine today after reading everyones recent inputs regarding Vacumn Leaks and P1313 and P1316 and related codes. It is correct that the line from the gas tank up to the charcoal cannister and over to the TB could also be a source of a leak?

What is that tube made of? I was on my creeper underneath spraying Mean Green and cleaning and degreasing everything and trying to do a good visual to see if I could see anything that needs fixed while I got some time and nice weather.

Overall, mine is looking pretty good for it's age.

 

Danny,

There's the line from the canister area and yes it could be a leak source. I pulled that line off and I dropped 3 inches of vacuum. I pulled off the line from valve cover and no change, I guess it is like a filtered air source for the PCV system that sucks out the other valve cover thru oil separator.

 

I am wondering if my sporadic P1316 may be either the charcoal cannister line or possibly even that brake vacumn line. Wonder how to best determine if either of those is good or possibly leaking?

 

Yeah, I don't think it really affects vacuum. Just seems like it should with it being plumbed to the TB, but seeing as how it is an open hose to the valve cover...it can't be a vacuum hose, just a breather.

 

Note in RAVE drawing that it shows air flow thru that hose in two directions, under certain throttle conditions the flow reverses. While side going to intake is one way only.

 

This line to the PCV is upstream of the throttle butterfly. If you remove the connection of the big rubberair intake hose you can see the port is in front of the butterfly. Engine vacuum is between throttle butterfly and intake valve in the head. I think this just lets the air flowing in the PCV system be filtered.

 

And in certain conditions, like wide open throttle, it could also reverse flow and suck in the blow by from pistons that enters the oil pan area, keeps the valley pan gasket from puffing up like a pillow. If you did not want that function, I would suppose you could put in a check valve and get one direction flow only, but that might make more problems for the truck. Also, when that oil separator gets clogged, it can increase pressure and make oil leak out of seals that normally have little pressure behind them.

 

Danny, FWIW....I too had sporadic, but persistant P1316....and occassionally I also had a "poor purge valve performance" code. In an earlier post regarding EricTyrell's troubles, I had decided that (in my case anyway) much of this was related to the evap system, I had read to smack the purge valve and it might reseat, that wasnt the prob, I replaced the purge valve with a newer one...that didnt fix it either. long story short.......I capped off the vac port where the purge valve connects to the throttle body .......that ended the misfire code. I then would get a "gross evap leak "code...I determined that the purge valve was on (open) as soon as the ignition key was turned on and never went off untill I turned the truck off....This created a constant vac leak with everthing hooked up normal, and a constant evap leak with the tb port capped off......I then capped off the purge valve .........no more codes. AND ,YES this would lead you to think that there is a leak in the evap system between the canister and fuel tank.....but I tore it all apart a couple of times and couldnt find any leak....even replaced the gas cap with a new oem one,
It is my understanding that the purge valve shouldnt be "on " ALL the time...mine IS.
just something for you to consider while tracing out your issue