A4 shifting question.
Thread Starter
Racer
Joined: Jul 2004
Posts: 433
Likes: 0
From: Camarillo CA.
A4 shifting question.
I just had 3.42s installed on in my 2000 A4 on Monday. The installer used LS1 Edit to reprogram the current Diablo program for the 3.42s. He also said he would firm up the shifts, even though I allready added 5% line pressure. Now after about 15 minutes of driving the low speed shifting gets very firm and feels as if it's slamming into 2nd and third gear. The car shifts perfect until the trans temp gets to about 150-160 then it shifts like a kick in the rear. All shifts @ WOT are nice and firm, just the low speed problems.
Any ideas, could something have gotten un hooked, could it be a programming problem, could it be low on fluid, could it need a trans rebuild ? What kind of signs do the A4 transmissions give when the need repair ?
Any ideas, could something have gotten un hooked, could it be a programming problem, could it be low on fluid, could it need a trans rebuild ? What kind of signs do the A4 transmissions give when the need repair ?
Drifting
Joined: Jul 2002
Posts: 1,589
Likes: 0
From: Fontana CA
Originally Posted by OOBlackconvert
I just had 3.42s installed on in my 2000 A4 on Monday. The installer used LS1 Edit to reprogram the current Diablo program for the 3.42s. He also said he would firm up the shifts, even though I allready added 5% line pressure. Now after about 15 minutes of driving the low speed shifting gets very firm and feels as if it's slamming into 2nd and third gear. The car shifts perfect until the trans temp gets to about 150-160 then it shifts like a kick in the rear. All shifts @ WOT are nice and firm, just the low speed problems.
Any ideas, could something have gotten un hooked, could it be a programming problem, could it be low on fluid, could it need a trans rebuild ? What kind of signs do the A4 transmissions give when the need repair ?
Any ideas, could something have gotten un hooked, could it be a programming problem, could it be low on fluid, could it need a trans rebuild ? What kind of signs do the A4 transmissions give when the need repair ?
Team Owner
Joined: Apr 2001
Posts: 54,204
Likes: 180
From: S.W. Ohio. . . . . . NRA Life Member
you may be seeing the P1870 error code as well with the tranny shifting like that.
I don't know if combining the Predator and LS1Edit was a good idea. There's more to the reprog than just shift points. The TCC Slip Table needs altered as well, or the PCM will be faked into believing there is too much tranny/TC slip and command extremely high line pressures to compensate (when there was no "real" slippage to begin with).
Why wasn't the Predator used exclusively
I don't know if combining the Predator and LS1Edit was a good idea. There's more to the reprog than just shift points. The TCC Slip Table needs altered as well, or the PCM will be faked into believing there is too much tranny/TC slip and command extremely high line pressures to compensate (when there was no "real" slippage to begin with).
Why wasn't the Predator used exclusively
Drifting
Joined: Jul 2002
Posts: 1,589
Likes: 0
From: Fontana CA
Originally Posted by Mike Mercury
you may be seeing the P1870 error code as well with the tranny shifting like that.
I don't know if combining the Predator and LS1Edit was a good idea. There's more to the reprog than just shift points. The TCC Slip Table needs altered as well, or the PCM will be faked into believing there is too much tranny/TC slip and command extremely high line pressures to compensate (when there was no "real" slippage to begin with).
Why wasn't the Predator used exclusively
I don't know if combining the Predator and LS1Edit was a good idea. There's more to the reprog than just shift points. The TCC Slip Table needs altered as well, or the PCM will be faked into believing there is too much tranny/TC slip and command extremely high line pressures to compensate (when there was no "real" slippage to begin with).
Why wasn't the Predator used exclusively
Team Owner
Joined: Apr 2001
Posts: 54,204
Likes: 180
From: S.W. Ohio. . . . . . NRA Life Member
it's a slip code error. In a nutshell, there is a table in the PCM that supposed to detect a slipping tranny/TC. It does this by comparing the RPM to MPH while in 4th when the TC is locked. (Though I have read that it happens in 3rd or 4th).
When you change rear axle ratios, you get more RPM at a given MPH than before.
If the new RPM is above the threshold set in the TCC slip table, then the PCM commands the tranny to increase line pressure to compensate... falsely thinking there is a transmission/TC problem. Of course there is no improvement, since there is really no increased "slippage".
Seeing no improvement, the PCM commands even higher line pressure. You eventually get neck-snapping shifts, and the PCM will eventually set the P1870 error code... and possibly the CE light.
So the error thresholds of the TCC slip table need to be updated to allow the increased RPM to be considered normal - due to your more radical rear axle ratio upgrade.
LS1Edit can do the job, if the operator knows what they are doing. The newer Predators can do the job... right out of the box. The older Predators will need a custom tune file generated.
When you change rear axle ratios, you get more RPM at a given MPH than before.
If the new RPM is above the threshold set in the TCC slip table, then the PCM commands the tranny to increase line pressure to compensate... falsely thinking there is a transmission/TC problem. Of course there is no improvement, since there is really no increased "slippage".
Seeing no improvement, the PCM commands even higher line pressure. You eventually get neck-snapping shifts, and the PCM will eventually set the P1870 error code... and possibly the CE light.
So the error thresholds of the TCC slip table need to be updated to allow the increased RPM to be considered normal - due to your more radical rear axle ratio upgrade.
LS1Edit can do the job, if the operator knows what they are doing. The newer Predators can do the job... right out of the box. The older Predators will need a custom tune file generated.
Last edited by Mike Mercury; Oct 8, 2004 at 01:15 PM.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Team Owner
Joined: Aug 2003
Posts: 38,314
Likes: 35
It sure sounds like a P1870.
The installer used LS1 Edit to reprogram the current Diablo program for the 3.42s.
Last edited by '06 Quicksilver Z06; Oct 8, 2004 at 03:14 PM.