I have a '99 Ram 1500 Quad 4x4 with the 5.2 . Normally get 12 - 14 MPG combined, 11 towing. Last week started getting 7 - 9 MPG combined, not towing. Service schedule called for new plugs so I installed Autolite platinums and new wires. No different other than better starting and runs better cold. Runs great, strong, just sucks fuel. No codes shown on diagnostic check. I'm stuck, any ideas?

 

Plenum gasket, search forum, topic beaten to death. No offense to the new member.

Welcome to DF!

 

welcome to df. don't get your feelings hurt by squirrels, he's just in a bad mood cause he's spent about 10 million dollars on his truck.

also might want to think about replacing front 02. also check plugs for fouling from leaking injector

 

HA! I actually laughed out loud at that.

Sorry for the curt response, I was multitasking too many threads at once.

 

Not to doubt anyone's ideas, but could it just be winter? my trucks always get a little worse mpg in the winter cold. I dont know why, maybe because of being cold at first. & just to let u know its not because i let it sit @ idle warming up, cuz i dont

 

could be cat as well

 

Thanks to everyone for the quick replies. I have already had the plenum gasket replaced at 60k miles. It used a lot of oil when that went bad. Not so now. The truck only has 80k. I was leaning toward the o2 sensor or cat. Any way to tell which may be more likely with no codes? I installed K&N filter and flowmaster muffler at around 70k which I hoped would improve mpg, but I'm going the wrong way.

 

can you drive faster than 50mph? if not it's the cat!

 

I had this same problem around Thanksgiving and noted that #6 and #8 spark plug wires were replaced wrong. Was dumping fuel, switched em back and runs just like prior to changing the plugs.

 

Sounds like a dodge to me. I'm only getting 10 in the city, never got more, never got less. Doesn't eat oil, plugs look fine, newer wires, newer cap and rotor. Sounds like the life of a dodge truck.