I have an 08 1500 with the 6.0 Vortec Max engine. Since new it hesitates bad between 1500 and 2500 rpm. Whats going on is its flip flopping between v4 and v8 at the same time transmission can't decide what gear to be in if you are driving with a light foot. If you put your foot in it it drops a gear and stays V8 and all is well. It just so happens that 65 mph is like 1800 rpm with the 20" tires.

Took it in under warranty and dealer said it was normal behavior There was another valve they were talking about shifting at the same time and said if it were not for my modified exhaust I wouldnt even know it which is BS. You can feel it bouncing back and forth. I have an aftermarket muffler and its a little louder with dual exhaust but not a lot louder.

I'm to the point of wanting the AFM shut off so it just stays in V8. Anyone else having this?? It would alos be nice if it cold be fixed. The v4 mode is a marketing move as it only stays there when costing anyway for the most part. I bought it to pull trailers and milage isnt a big concern. I have a POS Ranger for daily driving and good gas milage.
Thanks
John

 

custom tunes from someone like Justin @ blackbear performance can turn off the DOD. some people have claimed to get better mpg because of turning it off, some claim less mpg.

plus with that motor, remove 80% TM, and with his tunning you will probably see another 20-25hp @ the wheels.

 

Not only that but he could also fix the shift points so the tranny doesn't try and jump gears or shift back and forth between gears when pulling or normal driving.

With the tune you may also get bigger gains because of the other mods you have already done. That would also help! But if you are planning on doing a CAI as well then do it before you get your tune so you can get max gains out of the tune without having to get it tuned multiple times.

Good luck and let us know what you are doing to it and how it responds.

 

Tell us what ALL of the aftermarket parts that you have installed on your truck. You said you had dual exhaust, is it true dual? How many miles do you have on your truck?

 

The truck just turned 10k miles. At 500 I had the exhaust cut off ahead of the muffler and replaced with a low restriction single in dual out muffler. Its louder but not bad. I had a 2001 Suburban that we put a Flow Master on and it resonated something fierce inside the truck at certain RPMS and was not liked by the family members. THe muffler shop talked to thier supplier and ordered this one special for my truck its just right.
Other than that no mods. It does have the factory 20" wheels and I was wondering if I could take it to a sport truck place and have it it tuned without mucking up the warranty. Not sure what the tuners cost but might buy one, I restore tractors as a hobby including rebuilding motors, pretty mechanically inclined.
THanks!

 

Spent all summer modding the motorcycle and its done, see a CAI in my near future! Any idea if the Corvette servo mod is a possibility for the tranny behind the 6.0? Its supposed to be some HD tranny but its not an Allison.

 

Sounds like the problem is throttle related so I would check the TPS(throttle position sensor), and the MAF(mass air sensor). Both of those can cause wierd and unusual transmission shifts. Start there and find out.

 

all stock 700R4, 4L60, 4L60E, 4L65E, and 4L70's (Im sure i forgot one in there ) will benefit from a corvette servo upgrade. you can do this as long as its not the new 6 speed.
if i remember reading correctly you have a half ton with the vortec max package, its a slightly upgraded 4L60E, renamed as a 4L70E, so yes, you should get it done.

 

If it is under warranty then take it back again. And ask them if there is an update for the tranny or the drive by wire system. Keep harrassing them. If it feels funny take it back. If it sqeaks funny take it back. Make yourself a known customer that will not take it laying down. As farif it as a tune goes... it can void your warranty, but it also depends on the tech looking at your truck and the computer hooked to it. If he or she is smart and see it they can report it.... well you get the picture.
I had similar problems with my GMC Sierra and they never updated the computer until I was in there enough times and got a tech to ride with me before he looked into it. And WALA an update suddenly appeared that was out for 3 months... Go figure... Dealership + dragging their feet running warranty out = come back and charge you an arm and a leg for the update to correct the problem.

 

I agree about harrasing the dealership/s. Don't stand lower than them because this kind of thing definatly shouldn't happen obviously. The "super duty" transmission is the 4L70. I'm trying to learn more about this transmission in particular as it is relatively new. I don't think it has much difference from the 4L65 and 4L60s. I'm wondering (I don't think you would do this) if you had driven it a little hard in the begining since you said you had custom exhaust done at 500 miles. It's very tempting to hear all you can out of the exhaust once it's custom. Another thing...even though the owners manual says you might not even need to change the oil for almost a year! I don't trust that at all, when I got my truck I changed the oil at 600 miles, 1500 miles, 2500 miles, then again at 4000. Since then I change it between 2000-3000 miles. I'm a bit of an old schooler so I just wanted to make sure all the oil was completely clean during breaking it in. I didn't get the rpms over 3500 until after 5000 miles.