So I was going about checking the check valves in the vacuum lines. The one closest to the firewall I could blow both ways through it. Then I popped the vacuum line off of the intake manifold that has the 90-degree bend attached to it. In the process of trying to get it pulled out of the rubber hose the hose broke. So I drove around for a day with no vacuum line attached to the intake manifold.

Truck ran great!! Just had all the A/C flowing through the defrost and floor vents no matter what I did.

I blew through the check valve and 90-degree piece and there was very little flow in both directions. Not a lot of air actually gets thru.

So today I put a new rubber hose on and plugged the vacuum line back into the intake manifold. It ran like Poop! Tried to stall out at a stop light. Rough idle. No get up and go...etc, etc.

Gonna call the Stealership and see how much they want for both of those check valves on Monday. Wanted to hear what you guys thought.

 

Sounds like it's running rich when you have the vac line connected. The leak is causing it to run lean, so it performs a little better, but you'll burn up the pistons and or valves if you leave it off, so don't do that.

Maybe your o2 , ECT, or IAT sensors are faulty.

 

So will the check valves being replaced fix that?

 

It might fix the leak and your vents will work, but they won't fix it if it's running rich.

BTW, did you replace the precat o2 when you did the plenum?

 

No I did not replace the precat O2. I did pull it out for a bit to see if it ran better. It didn't run much better, and it didn't throw any codes while running it without the pre-cat O2. Was planning on replacing it when I replace the Y-Pipe down the road.

 

You need to replace it. Get one from the dealer or an NTK. And I wouldn't wait.

 

Roger that

(What is a NTK)

 

Hopefully that does the trick. Don't forget to remove the negative battery cable while you replace it. Reconnect when done, and give the PCM a few miles to reset everything.

 

What is the reasoning behind this. You think the sensor is shot due to the oil leaking thru the plenum? And this is messing with my mixure?

 

Yea, that's why it should be changed when the plenum is done.

And NTK is the brand.