im new to all this computer stuff and never had a truck with injectors nor a brain. how do i know if my plenum gasket is blown. truck runs amazing. just eats gas? its the 5.9 magnum and has 145k on it. no leaks anywere but my water pump gasket (im replcacing it) what are the signs of a bad plenum nd how much to fix it the right way if it is bad

 

Read the stickied plenum thread at the top of this forum. LOTS of good information there.

But, given the mileage on your truck, I would be that yours is blown.

 

lots of good information in that thread. sounds like my cats all clogged up. i get horrible gas milage. but other then that under a load my truck dosent ping it has alot of power and im not loosing oil or anything? does it mean its still bad? anyways so say i make this a weekend project. how do i go about fixing the plenum? were to i buy the aluminum plate and new gasket n all that nice new stuff imsure it needs

 

You can get a plenum plate off Ebay for 50 bucks. Gaskets you can source locally. There are literally dozens of threads on this topic, couple even have complete parts lists for this repair, and a few companion repairs, that will make you think you just installed a new motor.

 

wow it really improves the performance of the truck that much? i also have stock exhaust from the manifold to the cat i think my cat is cloged.. its getting new exhaust very very soon.so it would most likly to be smart to replace the plenum in the near future? now say i dont... is it going to kill my motor or just make itrun like crap

 

Runs like crap, spark knock, fouling spark plugs,excessive oil consumption, etc. Not to mention it eats cats. So, replacing your cat and NOT doing the plenum.... waste of money. (you should just send me a check instead. )

 

haha im not putting no cat back on the truck its getting a 3 inch pipe put in its place 2/14 pipe out 2 super 44 flowmasters and 4 inch stainless steel tips out the back and ya my truck really dosent knock or have any loose of oil or power? you think there a that slight chance i got one of the rare dodges witha good plenum still? lol

 

No such thing as a good plenum. That's a mythical beast. It may have been repaired already though..... have a look, see what ya find.

 

will do. thanks for your help. never knew what a plenum was lol. im gonna check it out today