Help with Gas Mileage....

[Kenrik]

Ok so I just got back from the gas station and I figured out i'm getting 13MPG!!! My dodge 3500 8.0L V10 gets 13mpg... that totally sucks I drive hard but not THAT hard... there must be something wrong with my car... I have within the past month replaced the O2 sensor, Coolant sensor, put in new NGK plugs/wires.. Cleaned the MAF. etc... I also have a brand new cone filter, I reset the ECU, I checked the PSI on all my tires before I tested my mileage... WTF is wrong with my car!! The only thing different that I did from normal is that I was running 89 octane when I usually run 93 I noticed that the car had less power running the 89 but it can't have made THAT big a difference on mileage... is my ECU toast? There must be something that is causing my car to run super rich and I need to figure out what.. Any Ideas??? any help would be GREAT!!

1989 KA24E 140k miles.

P.S. I just put in 8g of 93 octane (mixed the 89 and the 93 because it was running bad) and my car seems to be running better then it was.. don't know the mileage with the 93 octane yet...

WOOHOO 100th post..
Modified by Kenrik at 9:13 PM 8/22/2005

[naed240sx]

damn 13 is horrible. How did you calculate the mileage? Sounds like you pretty well covered all the bases as far as tune up goes. I would like to improve my mileage as well, let me know if you find out anything. One thing that helped my car out alot was seafoaming it. My car used to put out black smoke and idle really crappy on colder days (70 degrees)(texas). I ran seafoam in the gas, oil, and through the intake mani, and I never have any problems anymore. It feels way more powerful and idles smooth as glass. One thing I would reccomend doing would be to do at least a 200 mile test using the 93 and never flooring it or going above 3k, and seeing what kind of milage you get then. This will alow you to better determine how much of the problem is caused by driving habits, and how much is caused by you car having issues.

[halfassracing]

try checking the egr valve and all the vacume lines if the egr valve is not working properly then it will poor raw gas on the piston. ask an inspection place they will give you the spec.

[Kenrik]

Ok thanks... I know some of it is due to driving habits... I shift high and floor it in ever gear.. lmao... I kinda feel like if your friends don't instictivly reach for the Panic bar when they get in the car with you you're not driving hard enough... HAHA Also I can feel my clutch is sliping a little bit so i'm loosing power there.. I will check out the valve there is really not much else I can think of... never done Seafoam I hear that it's great!! I plan on picking up a few cans tomarrow... 89 octane is easier to burn and I usually use 93 so when I get a clean tank of 93 in her i'll do the test again (after I check the EGR valve etc..) if Anyone else has Ideas please post them Thanks!

[Kenrik]

oh... how did I figure out the mileage? well I filled it up went 100miles... filled her up again and found out that it was 7 point something gallons used a calculator... came out to exactly 13mpg (which was my guess before I even did the test)

[Kenrik]

Hmm did I replace the right coolant sensor? I replaced the larger of the two sensors in that area looks like that.. is there another one?

[e_c]

i was getting 200 miles to a tank.. in my 90... did seafoam, got new o2 sensor, PCV valve (<big one), spark plugsnow i get between 275-310 a tank... pcv valve.... well worth the 7 bucks

[InsanityInc]

If you floor it all the time and rev it up, I'm not surprised you get 13mpg.