I did my 1st tow with my 05 crew cab 2500 HD, here are some disappointing results. I would like to know if I can do anything to improve the mileage, and if this is normal for the Predator.
I only have 1600 miles on the truck now, and mileage with my other powerstrokes and Cummins trucks never got better with time.
I got 16.6 mpg with my truck empty on the 1st two tanks of diesel. I only use hand calculated method. I haul a 28' race car trailer that is gross 8800lbs with a V-nose. I set the cruise on 73 mph, 100 degrees outside air, fan stayed on 98% of the time (very annoying), the truck pulled great but only got 9.04 mpg! Very disappointing!!!!:help:
On the way back from the races, I filled the tank up again and I installed the Predator on the 65hp tune. The air temperature was only 83 degrees, the fan did not run (probably from being 20 degrees cooler outside) except when getting on the on ramp from dead stand still start. Same stretch of highway, set the cruise on 73 again, and still only got 9.46 mpg. Truck smoked a little on all uphill grades. The big problem is on gear changes the truck seems to slip the transmission, lock up the converter for a split second, and then go to the next gear change where it does the same thing again. This seems like it would tear a transmission up! What do you guys think?:help:
I unhooked from the trailer and drove another 70 miles home unloaded. On that drive, I still had the same shifting issues, and now I am extreemly concerned.
I am going to do the stack seal for the fan running issue in the heat, but the mileage and shifting issues I need some "real help" trying to figure this out. Do you think I have a bad programmer, or need to send this one back and get a different one?:help:

Funky shifting....

Your tranny needs to learn the new tune from the Predator. I'm not surprised that you had disappointing performance given that you just loaded the tune and towed. Not only that, but with stock tires at 73mph you are well above 2000rpms, which for many trucks is the magic number when going for mileage.

Do the stack seal and either do the fast learn with the Predator and tranny or give the tranny time to learn. The shifting should improve. Add a quality 4-inch exhaust and you'll reap more benefits, but be careful of systems that drone -- interior resonance -- since you tow.

We only run ours on the lowest setting when towing. That setting is easier on the tranny also. If you have a stock exhaust you might want to get an EGT gauge on there. It will scare the shi+ out of you on that setting. Predator is coming out with a new tune soon thats supposed to be great.

T-rex is right on with the stack seal and the speeds!

what is the "fast learn"?
the rpms were at 2200-2300. If I keep it at 2000 rpms it is only 65 mph & I will get run over around here.
How long will it take to Learn itself?
The good thing is that the tranny runs about 190 around town and never got above 200 while towing.
Are the biggest areas of concern on the stack seal on the upper portions of the radiator and on the sides at the top?
Do you think the exhaust will help mileage? I definatly do NOT WANT more interior noise.
If I change the tune, will it have to learn it again. This shifting thing is really scary to me.
Thanks for the replies. This site is great for GOOD information.

Fast learn...

From Diablosort -- "Take the truck out on an open piece of road, allow it to shift all the way up to high gear at cruise, then release the throttle and shift the truck down into low gear, not to worry it will not jerk down into low gear, foot off the throttle allow the vehicle to shift down through the gear progression until your riding along in low, apply brake, put the truck in Park, and do it again.
After two or three times, generally, you will see improvements right away, Allison has learned."

Exhaust might help economy -- your right foot and 256s will help more. No drone with a Corsa exhaust system -- pricey, but almost guaranteed no drone. TTS exhaust is good.

Probably need to do the seal and seal it good if you catch my drift. Check with killerbee.

Fast learn...

From Diablosort -- "Take the truck out on an open piece of road, allow it to shift all the way up to high gear at cruise, then release the throttle and shift the truck down into low gear, not to worry it will not jerk down into low gear, foot off the throttle allow the vehicle to shift down through the gear progression until your riding along in low, apply brake, put the truck in Park, and do it again.
After two or three times, generally, you will see improvements right away, Allison has learned."

Exhaust might help economy -- your right foot and 256s will help more. No drone with a Corsa exhaust system -- pricey, but almost guaranteed no drone. TTS exhaust is good.

Probably need to do the seal and seal it good if you catch my drift. Check with killerbee.

Hey T-Rex. Any comments on a 5' exhaust? (I'm looking.) If a 4" is good, wouldn't a 5" be better? How about sound and drone? Thanks a lot.

Ed

You need to look around in the Fuel System, Air, & Exhaust Upgrades forum. Do a keyword search. This thread will go off topic and the mods may feel compelled to move it.

I'll PM you to answer your question. What I have to say is not particularly anymore insightful on the subject than what others would say....

In short: It's an attention getter.

TRex, good points.

3D, with more speed comes more resistance, that means less mpg's. For every mph you increase speed there is a corresponding demand for more power, hence more fuel. Plain and simple! If you don't want to get run over ):h then accept lower mpg's. If you back er' down you'll spend much less time at the pump.

Exhaust upgrade with a kitty extraction will definitely help. Rick made a good suggestion about EGT gauges, NO GUESSWORK!

Sealing the stack will yield better mpg's, lower ECT's and EGT's. Good luck! JJ :)

Fast learn...

From Diablosort -- "Take the truck out on an open piece of road, allow it to shift all the way up to high gear at cruise, then release the throttle and shift the truck down into low gear, not to worry it will not jerk down into low gear, foot off the throttle allow the vehicle to shift down through the gear progression until your riding along in low, apply brake, put the truck in Park, and do it again.
After two or three times, generally, you will see improvements right away, Allison has learned."

i will have to remeber that, it took my truck a few days of driving to realy smooth out to some what normal shifting

moving to LLY electronics.. keep the LLY section for engine specific stuff. thanks