Hi all, I have searched the forums but not found much hhelp with this. I have a 01 1500 w/ 5.2L. I have put on shorty headders and a 3in Flowmaster cat-back exhaust. I used to get about 15mpg, however for the last few months i am only at about 9. I have no idea where to begin with this. I do know a few things need to be done with my truck. One being the rear pinion seal, speaking of which anyone know the size of the nut that i will need to remove. I didn't see it in the nut and bolt chart. I have read alot on the Plenum gasket, but I am nut loosing much if any oil, so I counted that out. I have no error codes showing up, so nothing alarming to explain this. Also, I have an Air F/X CAI, there is a hose going from the passenger side valve cover to the air tube. Should I be getting oil coming through this? It is not alot, just enough to make the inside of the tube wet.

Sorry if this is a garbled mess aof a message. Just trying to get my thoughts out. Any help on this would be greatly appreciated. If this has been covered feel free to direct me to the links, I will read up from there.

Thank you!

 

oil in the air tube?? pcv tube maybe??? no there should not be any oil in that try a new valve first but this should not be causing your problem I would think an o2 sensor maybe?? time for a tuneup perhaps?? Last time I had oil coming up through a pcv was caused by worn out rings. It could still be the plenum gasket do you get the pinging in the motor? I am new to the fuel injection world so please let me know what you find thanks

 

there is a breather on to of the valve cover like this

[IMG]local://upfiles/40785/0104034BCB08450194DE777D9E00AEB7.jpg[/IMG]

then there is a hose from that to the back of the airfilter box. u will have little suck thru enough to discolor the airfilter but if u got oil coming thru then its time to replace the breather as there is a mesh that absorbs the oil being sucked up .. and now that mesh is full of oil or just gone...

 

padodgeram had the hose I was talking about. Thank you. dfd737, I do not know what "pinging" is. I know a little about motors. Mainly my knowledge ends at oilchanges and replacing the air filter. However I do like to learn. As far as a tune up goes I just had one done to see if it would help the milage, no such luck. The guy at the dealer thinkg I am wrong with my milage. He says there is no wa possible since I am not getting any CEL errors. But, one thing I do know is that if you are only going 200 miles on 25 gallons of gas, you are below 10mpg. Any other Ideas would help. Thank again!

 

pinging......get up to 55 and step on it if you hear some kind of deseil like sound or a valve rattle that is pinging. 10mpg from 15 mpg is alot. replace the breather and try somthing else less expensive like the o2 sensor. Or just for grins pull the air filter and look at that replace if oily and dirty this is more likely the problem. While you have that off get a light open the tb and look inside the plenum if you see oil to 2 things 1. make sure it didnt come from the air filter(if it was oil soaked) and 2. if not 1 then I would thing the plenum gasket is bad. Let me know what the air filter looks like mine was so bad that when I replaced it I went up 3mpg!

 

Ok, so here is where I potentially get to feel like a complete idiot. A friend of mine reminded me that I got bigger tires a few months ago. The shop did not re-calibrate the speedo. I am also guessing this would skew the numbers I am seeing on my odometer? Possibly even enough to make it look like a large drop in the miles I get per tank. It sounds right to me. If so i feel dumb. But while I have a post going I have another problem I forgot to mention. When I idle my truck likes to rev it self up. It normally idles at about 700 rpm's. However everyonce in a while it wil kick itself up to about 1200 or so. It doesn't do this all the time. What would cause this and how can I correct it? Again, thank you for the input.

 

o2 sensor ?

 

With this "pinging" I get it when I romp on it however I have not noticed any oil comsumption. I will use the "light in the throttle body" technique to check though. I installed the round style air cleaner so it's not hard taking it off. If there is oil then what?

 

plenum gasket replacement. Call Hughes or who ever and get the aluminum plate or well enough has been writen do a search and look in the diy section I did not remove the fan as sugested though it was ok.

 

the reving once in awhile could be your iac motor needs some cleaning...it's on the back of your tb...just spray some carb cleaner on it...