Not true, you can see on a scan that the cruise does let the throttle close and it goes into DFCO while going down hills. Any speed above 35 and I use CC to hold more consistent throttle control and get better mileage.

 

I gotta 05 avalanche 5.3 with 4.56 and it reads 12.6 mpg but I don't think it's right and it's better on the highway

 

Ok I'm bored with this conversation. It no longer interests me.

 

Does anyone have a link to the E-fans mod? I am concerned about wiring them in seeing that there are probably no provisions in the stock harness for them.

 

I have had two 1/2 tonners with efans factory on them, and have not tuned either of them, but they don't get that kind of mileage.
In fact the NBS 07 with a 3.73 gear and Active Fuel Management does a little worse in all around MPG than my 05 with 4.10s and no active fuel management, going the same 3 states to the same places. Not sure how to explain that one unless the aero drag on the new trucks is worse. It is not a lot different, but I was expecting to see 1 mpg gain with the taller gears and AFM. However, that did happen. They are both 4 door 4WDs. They even have the same tires on them. For the record, the truck is hardly ever in 4 cylinder mode.
I am sure that the efans help, but you must do a lot, lot, lot of sitting in traffic to gain 3 mpg from it. That is all I can say. If that is the case, that should be the number one mod for any truck built before Efans were stock. If I could get that gain from my 8.1, I would be all in on that. Common sense tells me that there is something else helping you besides efans.
I think the tune will help the most. Because you can affect timing and fuel curves. However 15to1 AFR seems really lean to me. Isn't Volumetric Effeciency in the 14's somewhere. (Sorry for the big words, I just read that somewhere). I would think you would want to stay around that or a little below to keep the engine healthy.
I will tell you that I am not a physics guy or a mechanic. I just wrench for fun and read a lot of articles by people that know way more than I do, which isn't hard.

 

I just replaced my front 02 sensors at 113,000 and gained a mile or so back

With cold air intake, sweet throttle body spacer, Pacesetter lt's and y pipe, catback with flowpro muffler I am seeing 20-21 on the highway.

2wd reg cab with 3.42 gears helps I'm sure.

 

http://james.jaguar.net/agreif/fans/fanstech.htm

 

Well guys- I can atest that a tune does wonders, and I've just dissed the TM and upped the timming about 3/8's of a degree. My next palnned mod (OMG, did I just say mod?!) is an LS1 efan. I'll be hittin's somebody around here on the in's and out's. BTW, my gains thus far are 2MPG. The Lap Top went south on me so I need to get it back from repair B4 doing anything else, obviously.............

Oh yea- and when these tires need replacing I'll be going smaller to 265/75-16..........

 

has anyone seen an increase in highway mileage with a tonneau?

and do the efans help just in the city or on the highway also?

 

what size tire you have on there now?