Hey guys,
I just read this thread because it looked interesting, but it got me thinking. My 98 1500 is a daily driver (mostly highway). Going up the hills on the interstate everyday (gradual inclines nothing too steep), the rpms and mph just drop. It also gets a little jerky around 45-50mph.Replaced the TPS and installed an AEM Brute Force intake about a year ago and that seemed to help. Moved up to 285/75/r16's about 6 months ago and the problem seems to have come back. I'm hopingits not the tranny (replaced it about 2yrs ago). I've also been told that I don't need anything larger than the stock gears, so I guess that's not the problem. Just brainstorming here, soif anybodyhas any ideas as to why i'm decelerating that way, I'd greatly appreciate the input.

FYI, I'mrunning the Superchips tuner tomorrow and I have a 50mm fastmanTB.

 

It's b/c the OD on these truck and many others is weak as cat's ****... It is meant for level low-strain situations to drop your rpm's and save gas and engine wear. I have found that many OD's are alike...touchy and bogging. I turn my OD off unless I am on the interstate. If you hit an incline, even a high speeds, it is normal to shift out of OD. This was not meant as a power gear by any means. Regardless of what you've been told, 3.55 gears are too high for 285's. It won't snap an axle, but it's toohigh for top performance. You aren't experiencing anything out of the ordinary.

 

Mine used to sort of be like this. Once I hit 60 or so it just didn't seem to have much power left. You had to get on it for it to go. I mean not floor it but get on it some. Once I put the Hypertech on there it seems to want to just walk away from 60 very easily. I didn't expect a difference up in that power range but it seems to have helped. I guess thats what did it. I did the tranny and lsd in the rear at the same time along with plug wires. The wires weren't that old though and it didn't seem to miss. I don't know if this would help you but it seems to have helped me.

Then again it might just be you are in OD and have to floor it to get it back into 3rd. IF this is the case it's probably normal as they just don't have much power in overdrive.

You also might want to check your pleneum as it could cause a lack of power.

 

Thanks for the input. As far as the gears go, I guess I should move up to 4.10's?? I use plural because its a 4x4 (front and rear). Any idea on the $$$

Had the intake gasket (which I think is the plenum...kinda new to this) replaced at the dealership about a year ago. Apparently, the oil was basically pouring into the fuel and burning out that way.

 

I'd still check it as it's a good possibility that it's bad again. They seem to blow out fairly often unless you fix them with a Hughes or APS kit. The pan is steel and the intake is aluminum so they expand at different rates and blow the gasket. You need to get a kit like the two mentioned above with an aluminum pan or else you will keep replacing them. This is one of the things that you shouldn't take it to a dealer for.

 

Thanks hometheaterman.
Unfortunatly, I just changed the oil, so I don't know if its been burning like it was ( i don't think so though). Also, grey/black smoke came out of my pipes the last time (i.e. the oil burning out with the gas). I assume that when I put on the fastman TB, would also be a good time to put on the hughes kit if I see I need it. Kickin myself for not checking that oil before I changed it! Ah well, gota a week or two before the TB gets here, so I'll keep an eye on it.

Thanks again