Ok i Have a huge problem I have a 2001 dodge Ram 1500 with the 5.2. I just recently put on the airiad intake and throttle body spacer(which I have been told is a good paper weight) and the muffler is missing.....cheap mans exhaust. On top of that new spark plugs and wires 7mm wires and autolite racing plugs. I drove it to North Carolina from Colorado after all theses mods so I'm doubting those are the issue but never know. Last week the check engine light came on and i got 138 miles to a 25 gallon tank so i read the code it said it was the O2 censor which code be many things but i replaced it which didn't fix my issue. So I took it to the shop they replaced the mass airflow sensor and sodered the wires for the O2 and still yet the problem exists. I'm taking it back on monday but I was wondering what could be the cause of this with gas a 3bucks a gallon i cant afford 5mpg So any input would be appreciated.

 

oh and it has 116000 on it

 

Could be an injector or two are stuck open. You can use a stethoscope to hear them clicking (opening and shutting). It will also show up on a fuel pressure gaugeif you know what you were running before. If you can get hold of a scanner, look at your ltfuel trims. What was thecode #?

 

i dont think our trucks have mass airflow sensors, someone might want to double this, but if they dont go back and complain at the shop

 

The last two times I had this issue it was a direct result of the O2 sensor(s) going bad. If your truck is a Federal pollution model you have 2 O2 sensors, one each in front and behind the catalytic converter. One problem with my 01 is that it takes 2002 sensors. It's possible you have the wrong sensor(s) on it now.

if you have the California pollution model I think that you have 4 O2 sensors and two catalytic converters.

Also if you have a infrared temperature gauge, take the truck for a drive until it gets to normal operating temperature. then take some temp readings on your catalytic converter. I believe if the temp readings are higher toward the rear of the truck the converter is working, if it's hotter in the front it is at least partially plugged. Do you hear any rattling from the area of your cat? If you do a search on the forum here, there are a number of threads that discuss different ways of checking for a bad converter. BTW, with these Dodges you either must have a working catalytic converter and O2 sensors or have replaced all of that with o2 simulators. The engine computer goes nuts and the vehicle will not run right without this.

 

Aft 02 sensors are for diagnostic purposes only. Aft is the only place a simm will work.A bad 02 sensor will make you run rich for sure. 5 mpg rich??

Did the shop you took it to check your cat?

 

Are you going off the gas guage? Like filling it up, driving on a road trip, then when its on Empty filling it up and dividing milage by 25 gallons? Because your gonna be way wrong and off, the guage is never close to being right.

Go fill up, drive around until the guage says Empty, then go fill up again. NOTE HOW MANY MILES YOU WENT and HOW MUCH GAS THE PUMP SAYS YOU PUT IN!!!

When my guage reads E I go fill up and usually only get about 17 gallons into it...and these are 26 gal tanks.

 

I'm a bit suspicious of the shop "soldering" the connections on your 02 sensor.
My experience in the parts business tells me you shoudn't do this as the O2 sensor takes ambient air temp readings from the connector and soldering wires messes with the sensors ability to read that. Could be a bad convertor too, but I'd replace that 02 sensor with one that doesn't require a connector replacement. The closest thing to a mass air sensor is your Map sensor...I doubt that caused your issue.

 

Wear a lighter shoe on your right foot. lol

 

The shop I took it to replaced the map sensor in it and yes its 5mpg rich. When I take off I have a cloud of black smoke behind me. They have not checked the cat as far as I know so that could be an issue. And on the soldering I was told that u cant do any soldering around the O2 sensor itself but the only one they had to fit my truck was the universal type or wait 3 weeks for the right part.I bought the part they said it took to begin with and the connector was round and mine is square so maybe i do need the 2002 O2 sensor. I am curious though were is the map sensor I wanted to see what kind of job they did on it?