Just came back from a 1600 mile road trip. First time I had a chance to run it that far so I took my time and ran 65mph. First two fill-ups I got 14 mpg. After the second fill-up the check engine light came on. I didn't have my scanner with me so I just kept driving. Every fill-up after that, I got 19-20mpg!!! What the heck??? I'll pull the codes tomorrow, but I'm thinking why bother? The best I've had before was 16mpg. Once I pull the code, I'll post it so everyone can disconnect that "part" and get better mpg!! [sm=icon_rofl.gif]

 

Was that with the same type of driving, speed, etc...? Maybe its an odometer fault code, ha ha. Let us know what you find.

 

That's crazy. My CEL has been on since I bought the truck and I have noticed that I keep getting better mileage each time I fill up. I've gone from about 12 to almost 15 mpg running around town. Can't wait for my drive to Phoenix to see what my mileage is like on the highway.

 

So, AK, why are you not getting your codes read, whatever will show up will not be a positive message, and won't be adding to your performance, just setting yourself up for a possibly costly expense.
Mike

 

I have had my codes read and they are for bad O2s. I just keep forgetting about them when I have the money. I have a code reader and check them routinely to make sure nothing new pops up. I can go get all the go and get back to you if you would like but as of the last time I read them it was on for bad O2 sensors.

 

65mph is the key, I consitianly get 20+mpg on the expressway. I average 15 in daily driving.
I let it warm up for 10-15 minutes in the morning before and after work and still get 15.
If I do not let it warm up when it is cold out then I can watch my fuel gauge move as I drive, until the engine is warm anyway.

 

Checked it... P0138 O2 sensor circuit high voltage bank 1 sensor 2. I don't care as long as I get better fuel economy. And yes, I maintained 65mph on the highway the whole trip, using only 93 octane gas. Odd that it came on when I started it after my second fill-up and not while driving.

 

I'm all for better fuel economy, but if the mixture is too lean it will burn a hole in your pistons and exhaust valves over time.

 

IIRC, when an O2 sensor fault is detected, the system runs rich.

 

Just replaced my plugs and wires with Bosch Platinum +4s and Magnecor 8mm wires. Cleared my CEL codes and going to see which ones come back if any. Pretty sure I'll get my O2 codes back. My stock wires that were on the truck when I bought it were Belden High Temp wires. Junk I'm sure. Initial impression of the new plugs and wires is that the idle is smoother and truck is a little quieter. Haven't driven it enough yet to notice any change in power but I'll do a good test drive tomorrow or tonight after the football game. The plugs I removed didn't seem to be too bad off but definitely had a strong smell of gas telling me that the engine is running rich. Someone please correct me if I am wrong about that. I'll post pictures of the plugs if I can get some good enough that you guys can at least have and idea of the condition. Now I'm really curious to see if these new plugs and wires help my fuel economy.