I've been searching on here for the problems with my truck, I posted in the spark plug thread about one solution. I have a 1500 w/ the 5.2. My truck seems like it's running under a constant strain, it has loss power and the mpgs dropped big time. I replaced the plugs and ran some seafoam through the TB and that helped some, it improved the mpgs but not back to where they were. I've ordered 8.0mm wires and a copper dist. cap and rotor from summit. I also bought O2 sensors I'm replacing tomorrow as well. I keep reading about the plenum leaking but don't see anything about the symptoms. What are they? I read how to determine if it's leaking by looking down the throttle body but thats it. My truck has 191,000 miles on it and these problems just seem to have started all at once. How can I tell if maybe the CAT is clogged? I banged on it and it doesn't rattle. Sorry so long but i love this piece of junk and want it back to normal.

Oh yea, the brakes are not dragging.

 

For that cat: While you are changing out your O2 sensors, take the truck for a ride with the pre-cat sensor OUT. If it runs better..... cat is clogged.

Failing O2 sensors can have a detrimental effect on fuel economy. Changing them out is a good plan.

Plenum.... Joy..... The intake manifold on our trucks is two pieces. The upper aluminum kegger, and a steel belly pan on the bottom. That is what you are looking at when you look down the throttle bores. There is a gasket between the plate, and the manifold that like to blow out. If yours is blown, you may have any combination of symptoms. Excessive oil consumption. Spark Knock to one degree or another. Lack of low end power. Poor fuel economy. Shortened O2 sensor, sparkplug, and cat converter life. And assorted other issues stemming from a big *** vacuum leak, and burning oil.

Did you see any oil when you looked down there?

 

It will be tomorrow before I can check the plenum. I probably have a blown plenum gasket, i have most of those symptoms. Is there a write up on here? I'm going to try driving it without the o2 sensor as well. Thanks.

 

No pics, but, here is a basic write-up.

Let us know what ya find.

 

Didn't purpldodge do a write-up like a year ago?...

 

Hughes has a write-up with pictures linked on the Plenum Kit page.

Plenum Kit

Write Up

 

it looks as if I have the plenum leak. There wasn't any oil in the intake but it looks like there was some once upon a time and there is some wet looking sludge there. I ran a can of seafoam through the intake and have only drivien it about 100 miles since, that could explain why there's no oil present. I guess i know how my weekend will be spent. Thanks for the info guys!



edit: I've changed my mind for the moment. The oil sludge was where the hose connects from the PVC valve to the intake and I know it's the original so I replaced it. I found out I have to use 2002 O2 sensors for a 4.7 for my 2001 5.2 also which nobody has in stock so I ordered them. The truck doesn't run any different with the O2 sensor in front of the convertor out than it does with it in and it recently passed emmisions so I'm going to say the convertor is fine. It was a little hotter in front of the convertor than it was behind it with very little running. So I'll install the new plug wires, dist cap, rotor and sensors and see what happens. I may be just wishing but it's got tp be done anyway.

Anyone have any thoughts?

 

Just another quick question will a blown plenum make a truck smoke blue every now and then?

 

It could, because oil is going into the intake, thus burning up in your engine.