Shift Point Question?
Thread Starter
Intermediate
Joined: Jul 2008
Posts: 25
Likes: 0
From: Dallas Georgia
Shift Point Question?
Sorry guys, I know this may be a stupid question, but, I don't have experience in the tuning section. My brother-in-law has a silverado and wants to change his shift points with a hand held programmer. What is the difference and the effect of changing the shifts points negatively and or positively?
Thanks for the help!
Thanks for the help!
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 328
From: CA.
St. Jude Donor '13-'14-'15
It's rather confusing---But at part throttle operation--the shift is commanded by 1 parameter comprised of throttle position & MPH--
At wide open--it changes--The engine has to hit 2 parameters in order to command a shift--1 is MPH and the other is RPM---
A true full tuner can adjust all these tables correctly--however a handheld can only make small adjustments because if you adjust it too far it won't shift at all----a handheld when adding MPH to the shift points can only add it in the Part throttle area- at WOT you can set the shift RPM up higher but NOT the MPH parameter-- A handheld does not address BOTH parameter for a WOT shift--so on a heavily modded car or if adding or subtracting too many MPH at WOT you won't be able too or it may not shift at WOT---most handhelds have limiters to prevent you from going too far on a stock engine---where you can get into problems is using a handheld on a heavily modded engine which the handheld shifting program is not sufficient to correctly make it shift
Sorry to confuse you--this is the long answer--
The short answer---Add 3 PH to the 1-2 shift maybe 1 or 2 to the 2-3 and 3-4 shifts---set the shift RPM to 5600 in 1st---5400 in 2nd and 5200 in 3rd--- set the safety rev limiter to 6000----
IF you have larger than stock tires only make the changes in the 1-2 shift--You won't have enough power on a stock engine to set the WOT shift RPM higher and it will hang and hang forever at the 2-3 and 3-4 points before it shifts
PS: most improvements on an automatic are done with a real tune--I've seen cars and trucks gain 4-5 tenths in the 1/4 mile times without adding a single HP-trans tuning-for the street the best improvements are in tuning the DOWNSHIFT tables--these arent even addressed in a handheld--
At wide open--it changes--The engine has to hit 2 parameters in order to command a shift--1 is MPH and the other is RPM---
A true full tuner can adjust all these tables correctly--however a handheld can only make small adjustments because if you adjust it too far it won't shift at all----a handheld when adding MPH to the shift points can only add it in the Part throttle area- at WOT you can set the shift RPM up higher but NOT the MPH parameter-- A handheld does not address BOTH parameter for a WOT shift--so on a heavily modded car or if adding or subtracting too many MPH at WOT you won't be able too or it may not shift at WOT---most handhelds have limiters to prevent you from going too far on a stock engine---where you can get into problems is using a handheld on a heavily modded engine which the handheld shifting program is not sufficient to correctly make it shift
Sorry to confuse you--this is the long answer--
The short answer---Add 3 PH to the 1-2 shift maybe 1 or 2 to the 2-3 and 3-4 shifts---set the shift RPM to 5600 in 1st---5400 in 2nd and 5200 in 3rd--- set the safety rev limiter to 6000----
IF you have larger than stock tires only make the changes in the 1-2 shift--You won't have enough power on a stock engine to set the WOT shift RPM higher and it will hang and hang forever at the 2-3 and 3-4 points before it shifts
PS: most improvements on an automatic are done with a real tune--I've seen cars and trucks gain 4-5 tenths in the 1/4 mile times without adding a single HP-trans tuning-for the street the best improvements are in tuning the DOWNSHIFT tables--these arent even addressed in a handheld--
