OK go ahead and make me eat my words I know I am the champion of who gives a crap about fuel economy in a performance truck forum BUT I have been getting really crappy milage.

Running CLSD so trims are maintaining stoich once minimum h2o temp is met and even staying out of boost and driving conservatively I am getting less than 11mpg in town.

Now to be fair to my setup that is more time stopped than rolling and I know most of the gas spent is getting this pig off the line but still, I'd like to know if there is anything I can do to squeek out a few more mpg?

Airfilter is clean.
All systems are functioning great, truck hauls *** without even going into boost, in boost it screams.

 

What do your trims look like? I just recently got my truck running decently and I get 16mpg city and 20+ highway...

 

I will have to log a bit more since fixxing that O2 issue
So if trims are off more than 5% in areas that can cost mpg even though the pcm is correcting?

 

Try this...

http://www.nsc-ecofuelsystems.com/index.html

Don't laugh. I know several (at least 25 to 30) truck owners who saw improvement with this.

 

i usually get 17ish in town.. and thats with the 80E..

 

That is correct, mine are all 1-2%... IMO since your running in closed loop, I would recommend tuning your cruise cells (part throttle) with fuel trims (STFT or LTFT) instead of your wideband... There might be a small difference between the two, at least from my experience... Since your running closed loop, you might as well tune with the trims cause that is what is going to be controling your fueling when your done anyways.....

 

couldn't resist...

 

I'll add my take on trims. If they are correct...doing the right thing, adding or deducting a % of fuel due to a real scenario then I don't care if they are 20% off, you will not gain much by getting them in line. You may notice small, tiny fuel improvements and of course a tad bit of responsiveness (one has something to do with the other I bet). I just have never noticed a huge difference when I made big corrections. HOWEVER, if there is an issue with the o2's getting the wrong information then so is the pcm, then there goes fuel mileage.

Tuning by your trims will be fine today, but they will correct +/-2% tomorrow, and then different the next day. That's why you always here if they are +/- 5% then you are pretty much fine.

On the other hand, I feel ya...you are running 3.73's right? If you didn't get into at all for a whole tank of gas, I'd guess you should see ~13 mpg in town. I just...JUST NOW clicking on your domain realized you have the L33 5.3 HO. sigh....LMAO. 9.9:1 ?

 

Another thing you might wanna check/log is when your TC locks in 4th, while putting around town... Mine locks at 35mph with very little throttle... Since most of the city driving i do has a speed limit of 35mph... Works fine for me, some people don't like locking it that low, but it works well for me....

 

Makes sense to me, I'd be happy with 13mpg, very happy. I do have the 3.73 and 30.5" tires behind the L33 but I also have a 90mm TB, that can't be helping the milage either. If I wasn't stopping so much for traffic lights I think I'd have about 15mpg

I have the TCC set to only lock in 4th at speeds over 50mph...which I rarely hit. I have been thinking of setting the TCC tables back to stock and trying it again, I just remember lugging bad locking below 50 in 4th.