We drive 5k lb. aerodynamic bricks, fuel economy for us is a wet dream.

 

is there anything different from the 5.9 in my truck versus the 5.9 that was in my 99 dak r/t? that thing was hella powerfull and it was stock. i could bark the tires all day long from a stand still.

 

true. but it seems that all i was told was "you want better gas mileage? fix your plenum".

heyyou how long will the pcm be "learning" my patterns. and worse case i can reset it again right?

 

The dakota was hella lighter, you put big go-go in small area you get big go-go.

 

You can reset it any time you like.

It starts learning immediately. The further you drive, the faster it will learn. If you do mostly short trips, it will take longer. I always used to just go out and drive the hell out of 'em for an hour or so, and that usually did it.

Since the computer is still learning, expect fuel economy to vary a bit. You should pick some up once you start driving semi-normally again.

 

so its pretty much reset it and then drive like hell to get performance, or reset it and drive like miss daisy and get better mpg?

and any concern about it running even better when the front o2 is out after all this and no cat?

 

You need to pre-cat O2 sensor in there for it to do any learning at all. Without it, the PCM will stay in open loop, and run the engine off of its preset data tables. Lousy for performance OR fuel economy. That pre-cat sensor is friggin important.

 

but shouldn't it run the same while in that it does while out?

 

I found driving the 5.9 in my Jeep good throttle/hard better then driving slow. driving slow you just hang in 3rd gear for a long time before you reach 35-40mph for OD and the torque converter to lock which is where your best mpg is at..

So i always try to reach 40mph quicker then just sitting in lower gears trying to granny it once you get to 40mph and it locks you can just let off the gas and start rolling... to where if you granny drive you have to stay on the gas longer .. cause if you hang in 3rd thats where the 7-11mpg comes from. Torque converter locks is where 13+ is at. On my Jeep my overhead says 12.7mpg, i've reset the battery multiple times and sometimes i can make the computer read 13.3 or so but eventually it drops and stays at 12.6-12.7mpg. Last time i had the money to fill the tank up all the way to mess around with calculating mpg from the tank i got around 13.7-14mpg, which was mostly city driving. We got too many stops lights where i live... i hate it.

I also add'd a Cold air intake, and made a air scoop through the grill so air goes directly to the spectre cone filter.. I made a heat shroud all by myself, and i even put heat insulation around the intake tube. The tube was vastly cooler doing this, but all this did was increase the sound of the vehicle. No mpg increase. Then i found a K&N FIPK airhat, you know those big taller airhats with the 4 inch tube on them.. Bought it for $20 at the junkyard.. that increased my sound even more over using the stock 2 1/2 3inch airhat... and i think power has increased a lot also but the gas mileage hasnt changed.

 

No. not once the O2 sensor heats up, and the PCM starts paying attention. (closed loop.) By default, (open loop) your engine will run rich. Which isn't good for gas mileage. The PCM NEEDS the pre-cat sensor to correct fuel mixture, so you get the best power/economy from your engine, as it is burning efficiently.