Hey I have a 99 dodge durango 5.2 l slt version. It has new plugs cap rotor map sensor upstream o2 sensor. It's getting 13 mpg any ideas? No codes either I have run a fuel cleaner through it and has a good air cleaner on it.

 

Has it always done it or just recently?

 

13-14 MPG is pretty good and average for the 5.2L. If your planning on getting much better than that then you probably should not have chose a V8 SUV...

 

Well I know it's supposed to get 17 and 12 h/c. I'm mostly doing highway driving very lil city, and I don't live/work in big city. I used to get 15-16 I'm thinking purge valve or maybe canister needs replacing. It prob working and in spec just not enough to through code. Anyone know the range for the purge valve, and maybe the 02 downstream? So I could test with live data. Has it happened recently umm kinda, I drive it more in winter on the snowy or icy days. But I know last year it was getting 15 so, some time around late nov to March.

 

The Gov't rating for the '99 5.2L is 14 highway and 13 combined so again i would not worry about it. If you still wanna test things i would not worry about the Downstream o2 sensor as it has NOTHING to do with MPG.. All it does is tell the PCM that the cat is working right.

 

Well anybody else actually know the answer to my question? Let me be quite clear I WAS GETTING 16 MPG, last year. I'm not going any different length of distance. I'm doing probably 90 highway was and 10 city I drive about 3 blocks in the city in a 45 mph limit. It's a 20 mile drive so. I don't really care what others are getting so please don't waste my time with a stupid argument about mpg. I'm thinking faulty 02 sensor, evap, or vac leak. Yes a 02 sensor doesn't effect mpg but the cat does. I have tried to remove it but it doesn't wanna turn.

What would the range of readings be for them? Or could there be a different culprit? I'm taking it on a long trip starting today so I probably won't be able to fix it till I'm back. But any help would be appreciated.

 

Oh thats it. Be rude. Youll get lots of help.
I get 23mpg with my 99 Dakota 5.2 automatic 4x4 on 33's with 3:55 gearing.
So your way off. Swap all O2 sensors and buy Iridium plugs. Cold air intake. Space up the back of your hood 1/2" so air can flow through. Cools the engine and causes less drag. Lose the cat and get a free flowing muffer.
Headers. Intake manifold gasket. Lower temp thermostat. Larger tires to slow rpm. Roof fairing to cut rear drag. Side loovers help also.
loosen brakes a wee bit. Oil them some with WD 40. Helps reduce drag.

 

Try a different gas station maybe. I seem to have the best luck with shell and get anywhere from 17-19mpg on the highway.

 

as stated your well within the expected range of that engine/driveline setup,

however the biggest impact on mpg (if nothing changed) will be your personal driving habits, you can easily affect your mpg by 50% just by the way you drive, or the fuel you are getting, for example: winter gas will give you less mpgs than summer fuel (hell i went from 17 mixed in the summer to 14 mixed in the winter). as far as what hardware will affect your mpg, you are stuck w/ the pre cat O2 sensors (pre cat), the purge valve or canister will not affect mpg, it just collects stray fuel vapor from the tank instead of letting them go into the atmosphere.



i will also point out that being rude and jumping down peoples throats for their responses will not get you the help that you need, it will get you ignored at best and berated at worst.