I recently picked up a 2005 1500 RCLB 4x4 with the 4.8 and the nv3500 5-speed. I'm used to the 1996-1998 vortec motors without the drive by wire throttle body. I noticed that the throttle response isn't that great on my '05 and suspect it's because the computer is getting in the way. It doesn't feel or sound like the engine is laboring, it sounds and feels more like it's just not opening the throttle body up as much as I'm telling it to.
For example, in 4th gear, which is a direct drive, it has much better response and pulls pretty good even at only 2000 rpm. From the way it pulls in that gear you can tell it's got some power. So drop it down to 3rd and it should pull a little harder. Nope. Pulls just the same and loses some response and some of the howl in the exhaust like the TB isn't opened up as much. Drop it to 2nd and it's even less responsive and still cannot out pull what it can im 4th.
I've done a lot of searching and reading on this site about different tunes. There's a ton of useful information on here but most people are running automatic transmissions. It wasn't clear how much these 4.8's with a manual will gain from doing a PCM tune, whether the ones with a manual have torque management, and whether the tuner will allow you to turn it off. I see the place to turn it off when using an inTune is in the transmission part of the tune. It seems clear to me from driving my truck that the 4.8's with a manual must have TM from the factory. I could be wrong, but I'm a long time hot rodder, you can tell if the TB is open. A motor that's laboring feels and sounds different than one that's not being given any throttle. I'm going to order an inTune this week and dig around in the settings to see if the option to disable TM will be available. Has anyone else with the manual transmission tried this?
I am going to clean the MAF and throttle body as per the how to articles on this site as well. I'm sure it's due for a cleaning.
For example, in 4th gear, which is a direct drive, it has much better response and pulls pretty good even at only 2000 rpm. From the way it pulls in that gear you can tell it's got some power. So drop it down to 3rd and it should pull a little harder. Nope. Pulls just the same and loses some response and some of the howl in the exhaust like the TB isn't opened up as much. Drop it to 2nd and it's even less responsive and still cannot out pull what it can im 4th.
I've done a lot of searching and reading on this site about different tunes. There's a ton of useful information on here but most people are running automatic transmissions. It wasn't clear how much these 4.8's with a manual will gain from doing a PCM tune, whether the ones with a manual have torque management, and whether the tuner will allow you to turn it off. I see the place to turn it off when using an inTune is in the transmission part of the tune. It seems clear to me from driving my truck that the 4.8's with a manual must have TM from the factory. I could be wrong, but I'm a long time hot rodder, you can tell if the TB is open. A motor that's laboring feels and sounds different than one that's not being given any throttle. I'm going to order an inTune this week and dig around in the settings to see if the option to disable TM will be available. Has anyone else with the manual transmission tried this?
I am going to clean the MAF and throttle body as per the how to articles on this site as well. I'm sure it's due for a cleaning.