What gas are you running?
I dont drive my truck much but to the farm and to shoots and been averaging 15mpg just driving with out the converter locked up goin 45, and a tank last 2 weeks so that doesnt bother me.

But in my 4.3L work van i went from 18.5 10% crap gas to 21mpg just with using Ethanol free gas and changing the tune.

 

J, I've been usin the crappy 87 Oct. gas. I was using 91, & that's what I run say a week or 2 before I race. So ya, I run 87 mostly. If I'm not mistaken, it contains 10% E. I think even our 91 contains 10% Eth as well.

I was told awhile back the PCM automatically switches from various Spark Octane Tunes, according to fuel. I found that hard to believe, but wasn't sure. Then last night, I found somethin that causes me to doubt that info on HPT.

 

Use the manual controls to control the engine, then play with RPM and values till you get the highest VAC reading. Once you get that set your table to it, that will be the point where you will consume the least fuel.

 

Wow you still have stations where you live that have absolutely 100% ethanol free gas? Have you tested or had the fuel tested to confirm it? Not saying at all that I don't believe you I'm just surprised that their are still some parts of the country where you can get ethanol free gas these days!

I've tested the ethanol content at many many stations in Michigan and Indiana especially and I haven't found one yet that doesn't have at least 6% ethanol.

 

Manual controls? explain a bit more here if ya will. I mean when u have highest vac on a gauge, you're not consuming as much, but how does that correlate to these RPMs & values.

I thought Shell was supposed to have a lower E content. It seems when I've used Shell gas, my truck went farther on a tank. But that usu. means I'm outta MI, on a trip so that may have somethin to do w/. it, but still. Most every Sunoco I've been to it's 10%.

 

HPTuners calls them VCM controls, use the bidirectional controls (EFILive) to play with various RPM's and timing values. Look for the point where vacuum is the highest. Once you find those values, set your idle tune to them. the higher the vacuum, the more efficient your air pump (engine) will run and consume the least amount of fuel, plus should idle the best too. Vacuum doens't have to be on the gauge but monitor it trough the stock MAP sensor.

 

Never had it tested but it deff smells alot better than the EGas.. There is one plant in Meridian, MS that has the good gas for some reason, My buddy on the farm still gets a tanker load from them.
There is only 3 Stations i know of in this south/central part of the state that has the good gas.
Where you get it tested at?

 

I own an ethanol tester kit, bought it a few years ago and it has really come in handy.

 

Gotcha!

I really wanted to try some of these ideas in this thread. Just got home, so I'm really tired, so I guess now it has to wait another day or so.

I distictly remember seeing the VCM controls. I'll take a looksee.

 

I hooked up my HPT to have a looksee. Apparently I have a faulty o2.
I've heard of, & have been told to switch my front & back o2's if they're the same, which mine are indeed. When u guys are doin this, do u mean to just do it to verify o2 operation or permanently?

I thought that was a stopgap measure til I can get new ones but my rear 02 is the lazy or faulty 1, not sure if that changes your answer.

That said, anyone know the p/n for a new Denso o2?
Or best (as in cheapest) place to get em?
Or ~ how much I'm lookin at $-wise?