shiftpoints
 

My name is Justin and I'm new to the forum. The reason why I joined is to check out all the other trucks out there and to ask you guys and ladies questions about mine. I have a 2005 GMC sierra 1500 Z71 with a Fabtech 6'' suspension lift, 35x13.50 ProComp X-terrains, 18'' ProComp alloys, a K&N FIPK air intake, and a Hypertech Max Energy Programmer. I would like to get the very best out of my programmer and would like to know how i should adjust my shift points. As of now it is set at: 1-2: +300, 2-3:+400, 3-4:+500. Shift firmness is @ %75. My gears are still stock and my Rev. Limit is set at 6200. How do yall think i should adjust my shift points or should i continue with trial and error?

Justin,
Does your programmer give you an option for tire size? If so I would try that 1st.

Second when you say your truck is running stock gears, did you truck come with 35" tires? Most likely your stock tires were some where around 30" to 31" by changing to 35" tires you have reduced your effective gear ratio. This means you have lost pull power.
Assuming your trucks stock gears are 3.73 by changing to the 35" tires your effective gear ratio is now 3.17. if you started with 4.19 you are now at 3.51, if you started with 3.42 your effective ratio is 2.93 as you can see these tires have a direct on your trucks performance. On the street this should not be much of an issue pulling a trailer or off road you may feel like you have lost power.
Just a little food for thought

Good Luck
vp

thanks vp
 

Dear VP,
Thanks for your insight on my issue with my truck. That's one thing that I have not modified yet, my gear ratio. When I first got my truck, it was all stock. I was going to change my gear ratio but I was thinking maybe later on going bigger with lift and everything and just changing them then. I guess, changing to proper gear ratio will improve throttle response also? Thanks again, you helped me a lot.

Justin

Your shift points really depend on the camshaft the motor has. If its stock then set the rev limiter to 5800 and the shift points are usually 100 below that. With 35" tires, I would go with 4.10 gears to get back your torque and keep it economical.