What programming is REQUIRED for A4 gear change?
Thread Starter
Pro
Joined: Dec 2002
Posts: 695
Likes: 1
From: Edgewood WA
What programming is REQUIRED for A4 gear change?
I just can't stand to see that 3.42 rearend sitting on the garage floor so I'm getting ready for the big 2.73 to 3.42 gear change swap. I like to see what performance improvements each mod gives me, so I want to do the MINIMUM amount of programming until after I see what the 3.42's are going to do for me. Then I'll go for shift points, spark advance curve, etc. I was told that the speedometer is going to be wrong and that's the only program change that would be required. :party:
Safety Car
Joined: Aug 2000
Posts: 4,154
Likes: 1
From: Murphy TX
Cruise-In II Veteran
Re: What programming is REQUIRED for A4 gear change? (vrumvrum)
The speedometer will not be incorrect w/o programming unless tire diameter is changed. People repeat that there will be speedo problems ad nauseum without know what they are talking about.
However, you can all but bank on shift point and P1870 issues till you do you're programming. Part throttle shifts are not much of an issue (a little high), WOT shifts are likely to hang on the limiter. The P1870 stuff is a direct result of miscal.
If you're really in the "do something then measure" camp, you're a prime candidate for using LS1-Edit, Predator, etc yourself. (I'm an advocate of LS1-Edit. :yesnod: ) I presume you're wanting to hold off completely on programming until you can do everything at once? You will not want to wait very long for your gear programming to be done. It's possible to make only gear change related adjustments without doing any additional engine tuning.
However, you can all but bank on shift point and P1870 issues till you do you're programming. Part throttle shifts are not much of an issue (a little high), WOT shifts are likely to hang on the limiter. The P1870 stuff is a direct result of miscal.
If you're really in the "do something then measure" camp, you're a prime candidate for using LS1-Edit, Predator, etc yourself. (I'm an advocate of LS1-Edit. :yesnod: ) I presume you're wanting to hold off completely on programming until you can do everything at once? You will not want to wait very long for your gear programming to be done. It's possible to make only gear change related adjustments without doing any additional engine tuning.
Safety Car
Joined: Aug 2000
Posts: 4,154
Likes: 1
From: Murphy TX
Cruise-In II Veteran
Re: What programming is REQUIRED for A4 gear change? (Corvette Poor)
I know of only one person who claimed to have an HPP3 that offered 3.42 as an option for an A4 car. I was using an HPP3 prior to my gear swap, which I delayed until LS1-Edit was available. Sold my HPP3 after that. No an HPP3 won't do what you're after. The advertising is/was a bit misleading.
Don't try the tire scaling trick you hear thrown around from time to time. It works for F-body but will miscalibrate your speedometer.
The 3.15->3.42 swap is the only one that's a small enough change in gear to offer hope that you can squeak by for a longer time miscalibrated. Mike Mercury is the canonical example.
[Modified by ToplessTexan, 9:06 AM 4/20/2003]
Don't try the tire scaling trick you hear thrown around from time to time. It works for F-body but will miscalibrate your speedometer.
The 3.15->3.42 swap is the only one that's a small enough change in gear to offer hope that you can squeak by for a longer time miscalibrated. Mike Mercury is the canonical example.
[Modified by ToplessTexan, 9:06 AM 4/20/2003]
Team Owner
Joined: Apr 2001
Posts: 54,204
Likes: 180
From: S.W. Ohio. . . . . . NRA Life Member
Re: What programming is REQUIRED for A4 gear change? (ToplessTexan)
TTexan is correct. Depending on your C5 year (2001 and newer), you need do NOTHING in the way oof reprogrammign when going from the 3.15 to the 3.42 and retain your stock torque convertor.
Regardless of year, going from 2.73 to any other gear ratio will require a reprog. It has nothing to do with the speedometer and everything to do with the PCM's factory program not liking the higher RPM in each gear. Taking the 2.73 to any other ratio (even to the 3.15) is too wide a variance and the PCM will probably cause ackward shifting and will most likely throw error codes.
I think it has been determined that the Hypertech will not do gear rescalling properely on a C5 (although it will work fine on F bodies).
The Predator and LS1-Edit are viable DIY reprog options.
for those that haven't yet, visit my web page on this subject:
mikemercury.home.att.net/342.htm
Regardless of year, going from 2.73 to any other gear ratio will require a reprog. It has nothing to do with the speedometer and everything to do with the PCM's factory program not liking the higher RPM in each gear. Taking the 2.73 to any other ratio (even to the 3.15) is too wide a variance and the PCM will probably cause ackward shifting and will most likely throw error codes.
I think it has been determined that the Hypertech will not do gear rescalling properely on a C5 (although it will work fine on F bodies).
The Predator and LS1-Edit are viable DIY reprog options.
for those that haven't yet, visit my web page on this subject:
mikemercury.home.att.net/342.htm
Melting Slicks
Joined: May 2002
Posts: 2,911
Likes: 29
From: Mount Pleasant SC
Re: What programming is REQUIRED for A4 gear change? (vrumvrum)
do it, you will be so happy. I do feel my speedo is of slightly and the shift points are definently different then they where with the old gears. I am going to do LS-1 edit after I get my headers and converter in. But for now, the car seems to be okay. Good luck, as soon as you do that you will want more power and soon you will have the mod bug!
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
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
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
Team Owner
Joined: Apr 2001
Posts: 54,204
Likes: 180
From: S.W. Ohio. . . . . . NRA Life Member
Re: What programming is REQUIRED for A4 gear change? (1 slow 97)
I do feel my speedo is of slightly...
There is no guesswork here on that specific.
If you think you know better, then please provide your source.
Instructor
Joined: Jan 2003
Posts: 204
Likes: 0
From: clarkston mich
Re: What programming is REQUIRED for A4 gear change? (ToplessTexan)
The speedometer will not be incorrect w/o programming unless tire diameter is changed. People repeat that there will be speedo problems ad nauseum without know what they are talking about.
However, you can all but bank on shift point and P1870 issues till you do you're programming. Part throttle shifts are not much of an issue (a little high), WOT shifts are likely to hang on the limiter. The P1870 stuff is a direct result of miscal.
If you're really in the "do something then measure" camp, you're a prime candidate for using LS1-Edit, Predator, etc yourself. (I'm an advocate of LS1-Edit. :yesnod: ) I presume you're wanting to hold off completely on programming until you can do everything at once? You will not want to wait very long for your gear programming to be done. It's possible to make only gear change related adjustments without doing any additional engine tuning.
However, you can all but bank on shift point and P1870 issues till you do you're programming. Part throttle shifts are not much of an issue (a little high), WOT shifts are likely to hang on the limiter. The P1870 stuff is a direct result of miscal.
If you're really in the "do something then measure" camp, you're a prime candidate for using LS1-Edit, Predator, etc yourself. (I'm an advocate of LS1-Edit. :yesnod: ) I presume you're wanting to hold off completely on programming until you can do everything at once? You will not want to wait very long for your gear programming to be done. It's possible to make only gear change related adjustments without doing any additional engine tuning.
You will have to change your MPH shift points or you WILL hit the rev limiter, also make the change from 2.73 to 3.42 by some program,I used the LS1 Edit, thats all you HAVE to do. Then go play & have a lot of fun :cheers:
Thread Starter
Pro
Joined: Dec 2002
Posts: 695
Likes: 1
From: Edgewood WA
Re: What programming is REQUIRED for A4 gear change? (clancy)
Cool, I already have 2 other guys and myself to pitch in on LS1 edit, I get an income tax refund, got a good mechanic lined up. I'm going to have to think real hard about swapping the converter. I'll see if I can find someone around I can do a test drive.
I decided to get the 3.42 after visiting Mike Mercury's site a month ago. It's got a LOT of good info. :smash: :smash: A valueable asset to the Forum.
Hopefully LS1 edit is straight forward.
I decided to get the 3.42 after visiting Mike Mercury's site a month ago. It's got a LOT of good info. :smash: :smash: A valueable asset to the Forum.
Hopefully LS1 edit is straight forward.
