With an A4 going from 2.73 to 3.42...is tune required?
04-12-2007, 03:14 PM
#1
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With an A4 going from 2.73 to 3.42...is tune required? I have a friend that recently swapped his 94Z over to an LS1 and kept his 3.42 rearend. The donor car had 2.73's. He went from 6spd/LT1 to A4/LS1.
NOW, from what I thought the PCM controls the shift points and firmness and with having a different gear ratio in it the computer is not going to know when to shift since the signal from the speed sensor will obviously not be right.
He has been manually shifting the tranny to get it to shift at the right RPM but usually with an electronic tranny I thought it was a no-no unless you have a different valve body or shift kit.
NOW, from what I thought the PCM controls the shift points and firmness and with having a different gear ratio in it the computer is not going to know when to shift since the signal from the speed sensor will obviously not be right.
He has been manually shifting the tranny to get it to shift at the right RPM but usually with an electronic tranny I thought it was a no-no unless you have a different valve body or shift kit.
04-12-2007, 03:21 PM
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Originally Posted by SexyTransAm
a hypertech hand held will do what u need. and make the speedo right
Thats what I thought..probably could get one cheap on ebay.
04-12-2007, 03:26 PM
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Originally Posted by dsblk93gt
Thats what I thought..probably could get one cheap on ebay.
Just make you get the programmer for the year that the motor is. The 98 LS1's use one Power Programmer, and the 99-02 LS1's use a completely different Power Programmer.
04-12-2007, 04:23 PM
#6
... or have someone local that has HPTuner (or the like) and can reprogram the gear ratio. Much better then getting stuck with a Hypertech, for just a gear change. Just a thought. 
04-12-2007, 04:26 PM
#7
yea they r cheaper on ebay and more so on here and other sites. but make sure the part number is right for ur car. go to autozone.com or something and get the right part number.
and make sure that the 1 u buy isnt VIN locked!!! or u will have to send it to hypertech and have them unlock it and that will be more $$$
and make sure that the 1 u buy isnt VIN locked!!! or u will have to send it to hypertech and have them unlock it and that will be more $$$
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04-12-2007, 05:19 PM
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Originally Posted by 12secSS
... or have someone local that has HPTuner (or the like) and can reprogram the gear ratio. Much better then getting stuck with a Hypertech, for just a gear change. Just a thought.
Yea..trying to talk him into getting it tuned for the gears with some other friends that are going to dyno tune there cars.
04-12-2007, 05:44 PM
#10
Originally Posted by dsblk93gt
So what will happen if you drive it without the computer recalibrated? Couldn't that screw the tranny up??
Last edited by koolaid_kid; 04-13-2007 at 08:35 AM.
04-12-2007, 11:56 PM
#11
Originally Posted by dsblk93gt
So what will happen if you drive it without the computer recalibrated? Couldn't that screw the tranny up??
04-13-2007, 12:27 AM
#12
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about to go to bed... so only briefly read a few posts.. but .... be careful buying used hypertechs.... if they're not restored to stock (meaning everything , not just the power tune) it's useless to you
Best bet is to find someone local that can change the speedo cal (a gear change only takes like 10 minutes to read, change, BS a little, and then flash lol)
if you change gears, and don't have the PCM programmed/recalibrated there will be no damage.. but your speedo will be off (same for odometer and tripmeter)
If you have an auto trans car.. the shift points will be messed up... so don't go WOT ... but unlikely transmission damage would occur (since speed is off... shift points are off, but a stock car uses MAP to determine line pressure for an auto trans which has nothing to do with speed)
Best bet is to find someone local that can change the speedo cal (a gear change only takes like 10 minutes to read, change, BS a little, and then flash lol)
if you change gears, and don't have the PCM programmed/recalibrated there will be no damage.. but your speedo will be off (same for odometer and tripmeter)
If you have an auto trans car.. the shift points will be messed up... so don't go WOT ... but unlikely transmission damage would occur (since speed is off... shift points are off, but a stock car uses MAP to determine line pressure for an auto trans which has nothing to do with speed)
