91 tune-noticeable top end gain, no low end improvement, no gas mileage improvment

89 tune-noticeable top end gain, no low end improvement, no gas mileage improvment

87 tune-didn't really notice anything

tow mode-maybe some low end improvment? No top end, horrible gas mileage (I went from 13mpg to 10 without even towing anything)

fuel economy-no performance increases, +1 mpg

This is just what I felt/estimated in my '99 5.9l 4x4. I usually use the 91 tune with 89 octane gas and I have no issues. I have run the 91 tune with 87 octane and had no issues but I wouldn't recommend it.

 

you need an SCT for all that. Forget the chip

 

the manual says that the engine can start pinging on the 91 or 89 tune with 87 octane, but with a good plenum gasket it shouldn't ping.
i got different results on the short trip i took, as soon as i put it in gear it started walking faster then it normally does. and it felt more punchy through the gears until it hit overdrive. i'll have a little more diagnostic time (gas draining time) with it here shortly because i'm about to go to a town that is 30 miles away to weld a glass pack on.

 

I have had my 3815 for about 6 months now. It took a tank of gas before I felt a difference when using 91 Performance tune. You can run 87 octane gas with the 91 tune. Mine pinged like and SOB under hard acceleration. I am not 100% sure that the ping may or may not be plenum related. One nice thing about the 3815 is that it is internet updateable. Which basically gave me SC's new Mileage XS tune for free.( its basically the 87 tune with a little more performance). Just for S&G's I set it back to stock tune, and WOW. Needless to say it didn't stay on stock for very long. Mind you SC, or Hypertech are not "nitrous in a plug in". SCT tuners are custom mapped to your engine, they are still the best "pure tune" to your truck. But SC is stupid simple to use, and does do a nice job with the canned tunes it comes with. I recomend SC's to anyone who is looking for a very simple mod for thier truck, it does get rid of the death flash. I plan on using and keeping mine till I decide down the road what direction I wanna go with this engine.

Sheriff, the tire size adjusts the speedo to tire size. Its not 100% accurate, mine is 2 mph off when checked against my GPS.

 

i noticed the power off the bat, its just so much easyier to get up to speed

 

The 1:7 first if your really going to be modifying your rig. If your not into doing a complete turn around (complete modified overhaul) then go for the tuner. Most people are not going to get into serious modifications, therefore a tuner is the way to go. From the years I've been in modification there really is 2 different options out there.


As for "chips", The PCM on these rigs learn the settings then turn it down anyway. The only way around this is for you to reset the PCM when it learns the tune. This could be in 48 starts and up in the 300 mile range and/or longer. I do NOT support the use of "Chips" and instead support the use of tuners because you actually change the parameters of the PCM.

 

I sent you a PM

 

Finally got mine and installed the performance tune. The only difference I can tell is the TC locks up at 45-50 instead of 40 like it's been doing. I noticed no performance gains, which sucks. Boo.

Any thoughts? I do have 89 in it but noticed no pinging.

 

Oh, and it used more gas :P

 

That's exactly what I thought when I installed my 3815. No performance gains but the TC locked up later, which is nice. Now the engine doesn't lug at 1200rpm at 40 mph. I think that, and the fact that you can read engine codes makes the programmer worth it.