Here is my intro to the group.

I am newbie to the world of trucks and to gas engines, other than routine oil changes. I have a new to me 2001 5.9 4x4 and I am finding myself on a new learning curve. So I need your help.

In the past I did get pretty involved in my 82' TD diesel Benz's engine and on my Nissan frontier I changed the oil and just took it in for repairs. At 270,000 miles it died last week and I ended up buying this 2001 Ram from my transmission guy.

The truck has 110K miles on it, new transmission, heater core, radiator, shocks, and tires. I added the tires the old ones were dry rotted. I also added a K&N air filter and added a Superchips gas economy program.

I have had a couple of surprises so far. When I changed the air filter I found a mouse nest in there!! Surprise Surprise the gas milage suddenly went up. And when I changed the oil the old stuff looked like it came out of one of the farm tractors.

Two days ago I changed the oil and life was fine, 17mpg. I was happy and looking forward to changing the spark plugs next. Yesterday, it shifts kinda weird and I am only getting 10mpg.

Any suggestions on what I might want to try next or what the heck I did to the thing?

I guess some info that I could add: I didn't flush the engine when I changed the oil. Up top it looks clean, but I pulled some from the drain and it's black down there. I thought that I was being helpful and put in synthetic oil 5w30. I took a peek at the plenum plate and it didn't look cruddy down there.

Have at it. What did I do right? Was the synthetic oil a screwup? What do I need to do next? Is this thing sounding like it is going to be a project truck?

Thanks,

 

This thread would probably be better off in the tech section.

Using synthetic oil should not have hurt anything. If the plenum hasn't been fixed yet (for sure) then that's probably a good place to start or a close 2nd. I'm thinking a clogged/clogging catalytic converter could definitely have a negative impact on gas mileage, also the pre-cat O2 sensor.

Is the transmission shifting weird or a possible engine miss?

Have you changed the plugs yet or are they waiting to be done?

 

Welcome to the forum.

I agree with Stewie. Do the plenum, cat and O2 sensor. Even though the guy says its a new transmission it wouldnt hurt to do a fluid and filter change on it. Dont flush it though. While in there you can adjust the bands. You can download the FSM in the FAQ/DIY section. When you do the plenum also do a full tune up on the truck. It will be much happier and you will be to.

 

Shift kinda wierd - check the fluid while hot, idling in neutral.
10mpg - tap on the cat with a rubber or dead blow hammer to see if you hear a rattle and see if you can red line the tachometer (Just a quick jab up to the redline, don't hold it there). Also take the throttle body off to see if you have oil in the back of the intake manifold, having it off will give you a much better view and when it pools up it's at the back of the manifold.

You say two days ago and yesterday for mileage, are you reading the overhead console? Those things will get you in the ball park but aren't very accurate. I test drove a Ram one time that had one and thought it was funny when I floored it because it went from 16ish mpg down to about 4.

 

I would try placing the mouse nest back into the air box.

 

^ I thought the same thing.
Good idea I'd say.


Tune up, Plenum, cat. Do it! lol

 

I'm a former lab geek. I keep a running tally of mpg when ever I fill up.

I went by my tranny guy and and it seems to be shifting around 2300 rpm he says that is standard. eh I guess I am just not use to an automatic yet. Just like Stewie suggested the pre-cat O2 sensor was throwing a code.


I sent it to the shop today and they changed the plugs and went looking for vacume and what ever leaks. The O2 seemed happy so they passed on it. I'll change that myself tomorrow. I see that they sell special socket wrenches for that. Do I really need one of those things?

I'll see what the mileage is like then.

Plenum change will happen in a couple of weeks. Busy with my new job.

 

All you need for the o2 sensor is a big crescent wrench.

 

I used a pipe wrench.... Mine REALLY didn't wanna come out.

 

It came off easy peezy. Mileage went up to 15mpg after changing the pre cat O2 sensor.