poor mileage :(

[Boost]

By my estimation I should get 16-17 mpg. I am getting 13-14. My truck is a 2003 4.8 liter 2WD 4l60, stock with 105k miles. It is in good shape and running well, with new fluids and filters. It has (what I think) is lifter noise, despite synthetic oil (4 sounds per second). It has cheap Summit shorty headers wrapped, a rusty old Flowmaster, and a drop-in K&N filter, plus NGK TR55s gapped properly with MSD wires. I tuned it a few times, but with mixed results without a wideband, so it's currently back to stock. The alignment is not too bad at all and I keep the tires inflated to 40 psi (stock 17" wheels).

I am trying to figure out why the crappy 13 miles per gallon on a regular cab / short bed / 2wd??

So far I've learned that the headers make it rich at idle and I do spend some time idling in Miami traffic with the A/C on. I am practicing logging and monitoring to fine tune everything eventually, but I suspect if I tweak the idle richness out I may get some 16 MPG tanks out of it - can I adjust the idle speed VE to let it know about the airflow there? Or am I way off in my thinking?

And how can I best monitor and adjust slight variations off stoich at idle with my narrow band sensors?

Thanks, and I appreciate any other suggestions. I've already done some research on DFCO and Lean Cruise and also do not want to speed up the shifts because for a 1% improvement I'll take slow comfy shifts.

Sorry if this belongs to the "Tuning for economy" section, you can move it if you like.

I already have a bed cover and low viscosity synthetic tranny and rear fluid.

[WeathermanShawn]

I think the whole issue with Headers is that you are moving the O2 sensors farther back from the very hot stock manifolds location. Therefore, your narrowbands will read colder (higher mv) which in turn will allow 'more' fuel.

You could try the old school trick of lowering your O2 Switch-points at Idle. I don't know what they are tuned at now, but lowering them to perhaps 350-375 mv will allow you to run leaner at Idle. Thats about the only trick I know of. It actually works fairly well..

[Boost]

Thank you !!! That's exactly the kind of little thing I was looking for and you know your stuff too. Will try and see what I can learn / improve. They are in the stock location though.

[Boost]

I am getting in the low 15s now driving less agessive and I expect it to improve some since I am not warming it up any more before I drive. But I still need to fine tune it!