Lets get back to the topic:

So, the 1.5 - 2 MPG extra you were getting before you're not seeing now?


And, what's the difference in summer and winter gas?

 

I'm losing mileage, but I have at least three issues going on that may be affecting that.. I have a slight miss I'm trying to track down, I have some weird o2 readings (averaging 14~18% LTFT both banks), and I have a newly discovered need for ball joints, both upper and lower (yay me).. to add to the laundry list: My back cross block dowel gasket has failed, and me be spitting some oil yo, my battery is on the fritz (which can affect fuel trim), and with the cooler weather and the massive heat exchanges+ the ram air, I'm having trouble reaching expected operation temperature (hello open loop gulgulp)..

I'm not blaming the startron..

Winter gas is trash.. long story short- it uses a much MUCH higher percentage of butane... it has to do with Reid Vapor Pressure (RVP) and the boiling point of fuel blends in differing atmospheric pressures.. If you google it, you'll find more than you bargained for about it..

 

I too have noticed my truck is sipping more fuel then normal... Have also noticed that it seems like she's "chugging" when at idle, think I might have a slight miss or something. Maybe it's the clogged cat coming to get me......Time for some guttin'!

 

There ya go. Run the lowest octane rating available that does not allow pinging. If you want to spend extra money (and I do), buy Top Tier brands of the lowest octane rating you can get away with.

 

I was averaging 14% LTFT with my old cat which I discovered was gutted... seems to be around between 2 and 4% now...
I have a mis I cannot track down as well...leak down test on cylinder #1 passed with flying colors but I'm getting p301 and P300 errors randomly and actual poping while under load as well as a bad shuddder when the torque converter locks...I can't tell if the blue stuff is doing anything with all the changes I have done in the last month... the exhaust and possible the one 02 sensor I changed has dramatically changed the fuel to air ratio.... and my post cat 02 sensor reads a lot smoother with the cat in place...(I moved the precat o2 sensor to the post cat position) and replaced the pre cat sensor.

 

So I went a little while without using StarTron and my mileage starting dropping, back on the program and the last tank saw 14.3mpg

 

Yep, I can usually go 1 full tank without using Star Tron and still hold fuel economy but it starts slipping on the 2nd. I make sure I don't run out now...

 

reviving and old thread:

i'm back up to 14mpg's average now...

i blame old man winter, and silly cold intake temperatures with the isolated air intake.. I was seeing running temps of 180~184*, but intake temps around 25~40*.. the PCM was DUMPING fuel attempting to handle the extra mass.. that is my story, and I'm sticking to it!!

It could be that the winter blend fuel is leaving us southerners already, that could be at play too.. I hope not- because if I'm still into the winter blend crap, I can expect another 1-2MPG raise... 16MPG overall would be pretty dang sweet..

In the past two months, I got a grip on a misfire, an exhaust leak, and finally got my fuel trims into low single digit percentages.. all of that plays into it as well..

If I were to take my rig somewhere that has some elevation changes, and/or somewhere at a higher altitude, I'd likely be in the 12 range now, with hopes for the 14 range.. Sea level and no elevation changes certainly help, but I'm convinced that Star Tron does too.. What I'm NOT convinced about is Star Tron helping with the butane laden fuels the winter blends are known for.. The ethanol, yes- the winter butane, no..

I stand behind it.. Star Tron is good stuff.. so is a good tune.. so is properly inflated tires.. so is summer blend.. please, uncle Sam, bring the summer blends back NOW!!!

 

Welp I've been doing a ton of driving for work since I picked up some new stores, having to use my truck since the wife's car is running half-***'ed at the moment. Been using Star Tron and have been seeing some pretty damn good mileage over the last two tanks.

Run a tank out on Wednesday, got 15.1mpg and filled up again today got 15.5mpg, all rural and city driving, no interstate.

I'd be willing to bet it'd be 2-3mpg lower without Star Tron.

 

Avgas has quite a bit of lead in it ... 80/87, 100/130 and 100LL (Low Lead) usually have more lead than old style "Ethyl" auto gas. Those are basically the grades you find everywhere.

For 80/87 and 100/130, the first number is Lean Octane ... pretty much the same as the octane rating on pump gas (I think they call it "Aviation Lean Octane Rating").

The second number is Rich Octane ... supercharged, high altitude, rich mixture condition. There is no real automotive equivalent, but to get a rough idea of how much lead they use, they take basic 80 octane unleaded and then add lead until they get 87. Same with 100/130.

They don't use a set formula any more ... they only add enough lead to get the second number, whereas before it usually resulted in fuel that tested higher for the second number. That means less lead is used than before, but it's been that way for a long time; maybe before unleaded fuel arrived for cars.

100 LL has about half the lead that 100/130 does, but that's still about 2 grams a gallon. No second number, in other words not recommended for supercharged aircraft. I believe that's roughly the same as racing fuel lead content.

There is an unleaded avgas standard, but nobody actually makes that fuel, so you can't buy it. Some airplanes can use auto gas, but not from established OEMs. Basically homebuilts with auto engine conversions plus some Rotax engines.

Avgas has no detergent additives like auto gas does.

I've run 100/130 (you don't really want to run 80/87 in a normal-compression auto engine). The AME (Aircraft Maintenance Engineer; you have to do both in Canada so equivalent to Airframe & Powerplant endorsements together) had me add about 4 ounces of 2-stroke oil mix to a 20-gallon tank of avgas; said it will burn too hot otherwise.

The truck had no catalyst and was built for leaded fuel. I've mentioned before that I like old used vehicles; well the AMEs looked around camp and saw I had the only truck that could run leaded fuel, so over supper one day they told me to come on over to the strip. The fuel came out of a DC-4 that crashed and they were salvaging way up in Northern Canada. They had to load it into drums and ship it out, so they were happy to have me burn it instead. Saved the company money. They had a fuel nozzle hooked up to the wing tank; I just drove under it and filled up.

Truck ran really well; half way home I added 87 unleaded which would have been about a 50:50 mix, and you could feel a difference (not for the better). I probably could have made it the whole 300+ miles to civilization on the avgas ... normally I'd have a 1/4 tank by then ... but wasn't sure how it would affect my fuel consumption, and there is only one gas station along the way. Totally illegal in Canada, by the way ... you can't run leaded fuel off-road, in racing, nada. Airplane only.

I have a few more stories on using 100/130 but can't really tell them because others could conceivably get into trouble, so that's all I have for you.

Winter formula gas definitely does affect mileage ... I'm up 0.5 mpg averaged over the six months I've been keeping solid track on the PT Cruiser, 1 fill of summer, no other changes. The Ram still has winter fuel in the tank right now.

I've used Seafoam as a first fill additive on engines that sit all winter, but I ran across some evidence that it contains Alcohol, so it's off my list for now. Some of the Octane Boost formulas also have alcohol in them. Might try the Startron instead, as far as I can tell it's Alcohol free.