In the Transmission Only tune, you're probably OK with that spark advance, since the tune itself has not modified the engine parameters at all. I would be VERY careful about trying to advance the spark on either the Level 2 or Level 3 tunes though. The spark has already been adjusted in those tunes for best performance.

- Jack

Yep. I tried to advance the timing on Bill's Custom Performance, and immediately brought it back because the valve were rattling. Do you have any idea how far it's advanced in those custom tunes? Just wondering how much is (clearly) too much.

Drove to Auburn, AL last weekend and got 15.8 MPG on the Custom Performance tune. The tankful was probably 90% highway, but some idling around town getting out of game traffic. There were five people, with about 70 lbs. of sousaphones (marching tubas) in the bed.

I feel like I should be able to do a little better than that on the highway. Before I had my tuner, I actually got 18 hwy going to and from Auburn (just went, then came right back, so it was ALL hwy.

I am giving the Tranny Only tune another try to see if it's higher or lower than the 15.8. Obviously it's not a direct comparison because this tank will be only about 30% hwy. After that, I give the stock Towing a try.

I always calculate my MPG when I fill up. I WISH I was getting what the Gryphon says:)

Do not advance the timing on Bill's tunes. He is the automotive engineer. Five people and gear? That is like carrying an extra 600 pounds. That will have some influence on fuel mileage. Also, higher speed highway will have an effect compared to slow highway. For mileage comparisons you need to try them all under nearly the same exact conditions. That is how I found my tow tune actually gets the best mileage.

Heh. Found that out REALLY quick when I tried. that's why I'm playing around with the trans only tune instead I wish we could know the exact specs on Bill's tunes, but that would be bad for PHP's business. I know my truck will never get the mpg of my wife's minivan, but I want to get all I can. The Gryphon was designed as a performance tool, not an economy tool, I get that. But......if Bill were to write a "max mileage" tune I'd definitely be interested.
I guess you can only do so much with a 5000K-plus vehicle pushed by a 5.4l V8. I REALLY like my truck....everywhere but the gas station.

BTW-Is you Tow tune one of Bill's, or stock?

He isn't only adjusting ignition timing. Some of the gains also come from cam timing adjustments. He also has full access to fuel strategies and things I can't even imagine, especially part throttle where any gain would be found. Something you do not have access to.

He used to have mileage tunes and people hated it. It was weak in performance and people had this strange idea that they could load that tune up and hot rod around and it would give them better mileage. I'd say close to 70% of mileage gains are solely on the driver. Other things like maintenance and strategic modifications bring up the last 30%. Buy a vacuum gauge. It gives you real time manifold pressure (vacuum). More vacuum means less air, less fuel and better mileage. It trains you how to drive.

My tune was a custom by Cody. I had asked him to do a bunch of crazy things because it was a special application tune and, although it took a few tweaks, he pulled it off. It is only giving me 13-14 around town and up to 18 highway so nothing super special. Just consider that it will cost you 20-30 cents per mile to drive the truck. Want to cut down on cost? Streamline errands to minimize mileage.

Also, one tank is not a reliable test. If I showed you my mileage you'd see numbers ranging from 10 to 17.9.

Everything Longshot just said is bang on. I asked Bill for a tune that would maximize highway economy but still give me good passing performance when I needed it. As far as I'm concerned, he nailed it.

My truck, a 4x4 SCrew with a bed cap and factory tow is probably a lot heavier than yours. I get about 15.5 mpg in highway driving averaged over MANY tankfuls (I use a spreadsheet do do this). And, one factor that has a big effect is headwind. If I'm driving into a headwind at 70-75 mph, it probably cuts my mileage by at least 2 mpg.

Do try the tow tune, and don't "tinker" with it much. I think you'll like it.

One thing you CAN try though if you're trying for economy, is to change the part throttle shift and torque lock points. I reduced mine by the max for all upshifts and downshifts and gear ranges. My goal was to get the truck into the highest gear possible at the lowest speed with the torque converter locked. This has reduced the tendency of the truck to downshift so quickly on uphill grades and of course gets it into 4th gear at lower speeds. There's probably a bit of "point of no return" here, I may have reduced these too much, but I can't tell much difference between what I have and a more mild reduction. It's all about optimizing the engine load for efficiency.

This only effects part throttle acceleration. Wide open throttle is not changed.

- Jack

Thanks both of you. I have already reduced Converter lock the max amount on 1-2, and 2-3. I had it way dow on 3-4, but I was having problems with downshifting at unusual times so I brought it back closer to center. My shift points are lowered by only 1 MPH. Maybe I'll try lowering it some more. If I do, should I keep the downshift points matched with the upshift ones?

Yes, they must be the same to avoid transmission confusion and trouble.

Oh yeah. You told me that on another post. I was studying the graph you posted. What are the units on the axes? I would guess MPH, and RPM, but I'm not sure.

The graph is actually multiple graphs overlaid upon each other. The X axis is time from the start of recording. The Y axis is just a scale where the individual graphs must be multiplied or divided by factors of 10 to match. Or in other words, just the red line is MPH with the graphed line being 10x of the true value. The green line is 1/10 of the true RPM.