I just bought a 2000 with the 5.9L.
After a coule hundred miles I started to notice a slight miss at in town cruising speed.
A few miles later it has a definite miss, most noticable between 1000 - 1800rpms.
Now it is running very roughly, most noticable at lower rpms. Starts easy.
Truck has 80k, I plan on new plugs, cap, and rotor. Any suggestions if these dont solve the problem?

 

I would do a full tune up like you stated.

Regular Champion plugs gapped .040 (these are the $1.50 regular plugs)
OEM or MSD 8.5mm wires.
Cap and Rotor (get the upgraged Brass Contacts)
Fully clean the TB and sensors.
Could be the IAC sensor on the TB.

 

Thanks, Hydrashocker,
The plugs were brand new, wich scared the crap out of me,(someone has allready tied to fix), but then when I pulled the wires off of the cap, #7 cylinder post was badly corroded(on the outside) and the terminal in the plug wire was completely deteriorated.
Needless to say cap, rotor, and more new plugs fixed it.
What is this I hear about a plenum gasket? There was an oily residue inside the intake manifold.
Thanks for the info, and quick reply.
TB I get, but what is IAC?

 

Idle Air Control. It should be on the back of the Throttle Body.


You could clean it first and try that, before spending the money to replace.



Plenum Gasket is attached to the bottom side of the Intake Manifold. If you look down the Throttle Body and see oil, it is bad. It's not too bad of a job. I've been reading alot lately of them bad on the 5.9 Magnums.




IMHO Champion plugs are crap on the 5.9s. I love the NGKs or even use Autolites.



.02

 

Oh BS.

Dodge put millions of $ into building the 5.9L. They were built to run them so I call BS.

They only last about 25-30k but hey run good and his post shows it.

There will be some oil down on the belley pan from intake from the PVC valve but if there is excess amounts and oil comsumption then pull it and flip the intake manifold over to replace the gasket. Remember to install new gaskets for both.

This is an easy fix for the back yard mechanic.

 

So, the plenum gasket is the substitute for notoriously leaky intake manifold end gaskets. Is the replacement gasket any better, or does it require some help like the end seals did?
Always been partial to Autolite myself. Never ran NGK in a big motor, might have to try that sometime.

 

Hydrashocker,
So a little oily film is not an issue? Thats all I have.
I have learned plugs are kind of in the same catagory with religion, and politics: nobodys gonna change anybodies mind.
Thanks for the info!

 

A little film is ok.

After removal of the intake which is very easy you can flip it over and there is a cover. It is mounted by several bolts. This is where the Plenum Gasket resides. You just replace it and add a little RTV sealant (I like the gold one) and you are good to go. Install new intake manifold gaskets according to the manual. The one on top is the Plenum Gasket.

 

I said IN MY HONEST OPINION. As in, from experience. Everyone is different, sorry this is B.S to you.

 

Champions are great!. I always thought NGK plugs were for foreign cars? To each his own...
The PCV valve does let oil get inside the air intake. Later I will post pics of my PVC enhancer/ filter so you can see how much oil goes into the intake. If you are not burning alot of oil, or smoking out of the tail pipe, you should be ok. but I would still change the gasket.
BTW, can someone do a brief description of what has to be done to remove the intake. Like should one remove the distributor and other sensors along with the TB?