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Stuck in Commiefornia...
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And so it begins. I did it with the 6.0L, and I'll do it with the 7.3L. Started today by tuning my buddy's 2003 7.3L F-350. Did a 4-position chip, with a switch, and installed basic 40hp Tow, 85hp, 90hp, and 110hp base tunes from SCT. At this point we are looking at how the truck reacts, how it shifts and go from there.

While I'm at it, I'll be tuning my Early-1999 7.3L as well. The first step will be comparing the tuning on the chip to the tuning in the SCT SF3 I'm running now. I don't dislike the programmer really, but the ability to change tunes on the fly is really desirable. Once I get things sorted out I'll start refining the files to get the shifting the way I want it and perhaps increase the power a bit beyond the programmer's files.

I'll update as I go.
 

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Stuck in Commiefornia...
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Discussion Starter #2
Well, had some delays getting started on my own tunig, but things are finally moving forward. Went through the files for the 2003 and Early-1999 carefully, table by table, and updated the Early-1999 file everywhere possible, considering the Early-1999 has a far less sophisticated strategy. And with that I had a new base file from which all my new tunes will be written on.

I've also studied the various base tune files available to me from SCT, ranging from 40hp to 110hp. Now, I'm not new to tuning, gas or diesel, but I haven't really studied a particular tune nearly as intently as this in the past. What I have found is that there is a lot of room in the stock 7.3 calibration to improve the resolution. So I've worked on a lot of the areas that were lacking resolution like the throttle map. So far my base calibration, and my improved resolution files are great.

The surprise of surprises was my first attempt at a small power gain, something I had hoped would be about 40-50hp, well, it's closer to 100hp, and the truck feels fantastic. No codes for high exhaust back pressure or wastegate function, no issues with ICP. Just a small puff of smoke from a heavy application if throttle that clears up immediately. I'm super excited, and the next test will be running this tune on my buddy's 2003.
 
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Stuck in Commiefornia...
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Discussion Starter #3
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ADMIN/MAFIA
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The on the fly 4-6 position chips are nice for the 7.3's as you have instant transm tunning to match. To bad for us 6.0L owners, we can't have that due to the type of PCM we run, and it must be flashed each time to have the transm tunning. I still have my old Hypertech inline sitting around in a box, but it's a tranny killer for the 6.0L.

Harry
 

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Stuck in Commiefornia...
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Discussion Starter #6
Its been quite a while since I've updated this thread. Partly because I wanted to have something significant to update. Partly because I have needed to do some other things to the truck. Since I finally took the time to install the pyrometer probe in the exhaust manifold yesterday, and was able to get everything working properly today (I'm using a very old Autometer EGT gauge,) I was able to do some testing.

The tunes have evolved a bit since my last post. I've done significant work to the transmission functions, as performance wise I was already very happy. So the first thing I worked on was the shift schedule. Stock the truck shifts into overdrive and locks the converter rather late. Being an Early 1999 model truck, the transmission portion of the tune is not nearly as sophisticated as the later 7.3/4R100 trucks. But that doesn't seem to be an issue now. I took quite a lot of time and worked through the transmission section extensively. Shift pressure and shift schedule were completely revamped, as was the torque converter lockup schedule. After about two dozen minor changes and driving tests, I finally reached the current settings.

The results are fantastic. The truck can be driven any way you like, meaning you can put around in it like you have not a hurry in you, or you can drive it like you stole it, and it's perfectly happy anywhere between the two extremes.

So driving it like you stole it, this thing gets with the program. It has no issue getting up to freeway speed on even the shortest on-ramp. At the same time, smoke is modest, even minimal, and if you aggressively roll into the throttle rather than stab the throttle, there is minimal performance difference, but smoke is practically nonexistent. Once at speed, the transmission programming works well to minimize lugging and prevent smoke as well by downshifting when appropriate. The best part though has to be the EGTs. Testing on a 6% grade from 10-90mph generated a whopping 1150° peak exhaust temp.

For simple pleasurable operation, meaning you're not forced to rush, it's a wonderful smoke free experience that is still more responsive than stock by far. The biggest differences notable to this operating style is that by remapping throttle input, I've made the input more linear across the entire operating range, in fact, you could say it responds to pedal input more like a 6.0L, and that was what I was going for. This is where the efforts in transmission and torque converter operation really shine through though. Under moderate throttle, the transmission shifts at about 2000rpm and the torque converter locks up at about 1700rpm in third prior to the shift to overdrive. The entire driving experience is different from the original 1999 model and feels much more thought out and precise, almost like you are driving a later model truck like the 6.0L/5R110. Finally, EGTs at cruise run 550-625° from 55-75mph, so very pleased with everything.

Next up is testing the tow tuning.
 
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Stuck in Commiefornia...
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Discussion Starter #7
I forgot to cover the fuel economy.

Completely stock the truck managed 15mpg highway. Not great, but I didn't expect it to be. With the 6637 filter and 4" intake, straight piped to the stacks, and SCT canned tunes, I was able to get 16.5mpg highway. Big improvement, but not as much as I wanted. I added Archoil AR9100 when I serviced the truck and switched to my own tunes. Early tunes were resulting in 17mpg, and with AR6200 fuel additive 18mpg. The latest tunes however are resulting in 19.5mpg with AR6200. It will be interesting to see the results of this tuning and AR6200 after running the new AR6400-D through the truck. Would be nice to crack into the 20mpg range solidly before lifting the truck and installing larger tires.
 
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