Trans tune issues, experts needed
Thread Starter
12 Second Club
iTrader: (12)
Joined: Oct 2007
Posts: 1,340
Likes: 1
From: Dayton, Ohio
Trans tune issues, experts needed Here’s the cliffnotes of a problem I am having.
Bought new rear end with 3.70 gears (used to be 3.23s). Changed speedo settings in HP Tuners to compensate for new ratio and tire height. Speedo is reading correctly.
Went to track and car hit rev limiter at 1-2 and 2—3 shifts
Lowered commanded shift rpms AND mph in the tune. This fixed the 1-2 shift but not the 2-3. Logs were showing trans slippage and fluid smelled burnt so I replaced it with a built FLT 4L60E.
I go back to the track yesterday with the new trans.
1st pass: Spun real hard, lifted, got back in it and ran it out. 1-2 shift was commanded at 5400 rpms and happened around 5700. 2-3 shift commanded at 5400 rpm and happened around 6100. MPH tables were set 4-5 mph lower to allow rpms to control the shift.
2nd pass: Raised 1-2 shift rpms to 5650 (kept mph the same), Kept 2-3 commanded shift rpms at 5400 and lowered shift mph about 5 mph lower than the logs were showing at 5400 rpms. 1-2 shift happened at 6000 rpms and 2-3 banged rev limiter (6200 rpms) and I lifted.
3 rd pass: Lowered 2-3 shift rpms and mph even lower (5000 rpms) and the car did the exact same thing.
My logs of the runs show the “Current Trans Gear” parameter in HP Tuners. It shows the current gear as 3 rd , then 4 th right after hitting the rev limiter, but the transmission never shifted until I let out of the gas.
I have hundreds of runs on this car with zero issues until I swapped the rear end, so I suspect that it is throwing off something in the tune to cause this issue.
Any help would be appreciated.
Bought new rear end with 3.70 gears (used to be 3.23s). Changed speedo settings in HP Tuners to compensate for new ratio and tire height. Speedo is reading correctly.
Went to track and car hit rev limiter at 1-2 and 2—3 shifts
Lowered commanded shift rpms AND mph in the tune. This fixed the 1-2 shift but not the 2-3. Logs were showing trans slippage and fluid smelled burnt so I replaced it with a built FLT 4L60E.
I go back to the track yesterday with the new trans.
1st pass: Spun real hard, lifted, got back in it and ran it out. 1-2 shift was commanded at 5400 rpms and happened around 5700. 2-3 shift commanded at 5400 rpm and happened around 6100. MPH tables were set 4-5 mph lower to allow rpms to control the shift.
2nd pass: Raised 1-2 shift rpms to 5650 (kept mph the same), Kept 2-3 commanded shift rpms at 5400 and lowered shift mph about 5 mph lower than the logs were showing at 5400 rpms. 1-2 shift happened at 6000 rpms and 2-3 banged rev limiter (6200 rpms) and I lifted.
3 rd pass: Lowered 2-3 shift rpms and mph even lower (5000 rpms) and the car did the exact same thing.
My logs of the runs show the “Current Trans Gear” parameter in HP Tuners. It shows the current gear as 3 rd , then 4 th right after hitting the rev limiter, but the transmission never shifted until I let out of the gas.
I have hundreds of runs on this car with zero issues until I swapped the rear end, so I suspect that it is throwing off something in the tune to cause this issue.
Any help would be appreciated.
Moderator
Joined: Aug 2010
Posts: 7,323
Likes: 529
From: Ann Arbor, MI
When you say the MPH tables were reduced, I assume you mean the "Full Throttle Shift Speed" both Normal and Performance tables. Also assume you changed the "Full Throttle Shift RPM" both Normal and Performance tables. (Since I don't know when/how my PCM is in Normal or Performance mode, I set both tables the same for MPH and RPM.)
Note: Setting the "100% Throttle" column in the "Partial Throttle Shift Speed" is not the same. The setting "Full Throttle Enable" determines at what % throttle the "Full Throttle..." tables are used.
Perhaps you already know all this, but please confirm.
Note: Setting the "100% Throttle" column in the "Partial Throttle Shift Speed" is not the same. The setting "Full Throttle Enable" determines at what % throttle the "Full Throttle..." tables are used.
Perhaps you already know all this, but please confirm.
Joined: Aug 2007
Posts: 24,241
Likes: 89
From: Turnin' Wrenches Infractions: 005
Let me give a couple of pointers from my time fooling around with my 60 hitting the limiter.
1. Commanded mph must be met BEFORE the commanded rpm. Meaning log rpm vs. mph and set a mph that is 3-5 mph below your commanded rpm.
2. 1>2 is usually dead on or within 50 rpm of commanded rpm
3. 2>3 is usually 2-300 behind commanded rpm, but sometimes fluctuates, see #4.
4. Actual vs. commanded changes and is never 100% steady. Meaning just because it doesn't hit the limiter one time doesn't mean it won't any other time. I attribute this to differences in fluid temps, etc. Leave yourself a margin of error.
5. Read the A4 tuning sticky here by Coolaid, it can only help you. You need proper pressures to keep the clutches from slipping/burning.
6. Maintain proper fluid level for pressure consistencies.
7. Raise your limiter to gain a bigger window.
8. Make sure all your tables match for WOT stuff, including the part throttle table that lists a 100% throttle column.
1. Commanded mph must be met BEFORE the commanded rpm. Meaning log rpm vs. mph and set a mph that is 3-5 mph below your commanded rpm.
2. 1>2 is usually dead on or within 50 rpm of commanded rpm
3. 2>3 is usually 2-300 behind commanded rpm, but sometimes fluctuates, see #4.
4. Actual vs. commanded changes and is never 100% steady. Meaning just because it doesn't hit the limiter one time doesn't mean it won't any other time. I attribute this to differences in fluid temps, etc. Leave yourself a margin of error.
5. Read the A4 tuning sticky here by Coolaid, it can only help you. You need proper pressures to keep the clutches from slipping/burning.
6. Maintain proper fluid level for pressure consistencies.
7. Raise your limiter to gain a bigger window.
8. Make sure all your tables match for WOT stuff, including the part throttle table that lists a 100% throttle column.
Moderator
Joined: Aug 2010
Posts: 7,323
Likes: 529
From: Ann Arbor, MI
Obviously raising your rev limit depends upon your risk tolerance and engine mods. I have dual valve springs and set my rev limit at 7100. That way I can quickly change my shift points at the track by only changing the Full Throttle Shift RPM.
Also, you can set a much lower rev limit for just Park/Neutral, which helps overrev in those positions.
Thread Starter
12 Second Club
iTrader: (12)
Joined: Oct 2007
Posts: 1,340
Likes: 1
From: Dayton, Ohio
Thanks for the ideas guys. It always helps to have other people "check your work"
Both the mph and rpm tables were changed for "Performance" and "normal". I also changed the 100% column in the part throttle table to match the WOT tables.
This is all good advice and I have done most of it. Fluid level was checked and re-checked, trans temp was 170 and I believe all the part throttle tables match the WOT tables.
I would rather not raise the rev limiter due to my stock valvetrain. I'm not sure it would do any good though because nothing I do it the tune seems to have any affect on when the 2-3 shift happens. It may not even shift even if it had more rpm to do it.
I ran across some stuff on the HP Tuners forum that I am going to try today. I am going to log output shaft rpms to calculate the actual mph that the trans thinks it is seeing and use those values to command the shift.
When you say the MPH tables were reduced, I assume you mean the "Full Throttle Shift Speed" both Normal and Performance tables. Also assume you changed the "Full Throttle Shift RPM" both Normal and Performance tables. (Since I don't know when/how my PCM is in Normal or Performance mode, I set both tables the same for MPH and RPM.)
Note: Setting the "100% Throttle" column in the "Partial Throttle Shift Speed" is not the same. The setting "Full Throttle Enable" determines at what % throttle the "Full Throttle..." tables are used.
Perhaps you already know all this, but please confirm.
Note: Setting the "100% Throttle" column in the "Partial Throttle Shift Speed" is not the same. The setting "Full Throttle Enable" determines at what % throttle the "Full Throttle..." tables are used.
Perhaps you already know all this, but please confirm.
Let me give a couple of pointers from my time fooling around with my 60 hitting the limiter.
1. Commanded mph must be met BEFORE the commanded rpm. Meaning log rpm vs. mph and set a mph that is 3-5 mph below your commanded rpm.
2. 1>2 is usually dead on or within 50 rpm of commanded rpm
3. 2>3 is usually 2-300 behind commanded rpm, but sometimes fluctuates, see #4.
4. Actual vs. commanded changes and is never 100% steady. Meaning just because it doesn't hit the limiter one time doesn't mean it won't any other time. I attribute this to differences in fluid temps, etc. Leave yourself a margin of error.
5. Read the A4 tuning sticky here by Coolaid, it can only help you. You need proper pressures to keep the clutches from slipping/burning.
6. Maintain proper fluid level for pressure consistencies.
7. Raise your limiter to gain a bigger window.
8. Make sure all your tables match for WOT stuff, including the part throttle table that lists a 100% throttle column.
1. Commanded mph must be met BEFORE the commanded rpm. Meaning log rpm vs. mph and set a mph that is 3-5 mph below your commanded rpm.
2. 1>2 is usually dead on or within 50 rpm of commanded rpm
3. 2>3 is usually 2-300 behind commanded rpm, but sometimes fluctuates, see #4.
4. Actual vs. commanded changes and is never 100% steady. Meaning just because it doesn't hit the limiter one time doesn't mean it won't any other time. I attribute this to differences in fluid temps, etc. Leave yourself a margin of error.
5. Read the A4 tuning sticky here by Coolaid, it can only help you. You need proper pressures to keep the clutches from slipping/burning.
6. Maintain proper fluid level for pressure consistencies.
7. Raise your limiter to gain a bigger window.
8. Make sure all your tables match for WOT stuff, including the part throttle table that lists a 100% throttle column.
Yes, all good stuff. While I didn't mention it above, I also keep my "Part Throttle 100% column" in agreement with my Full Throttle table.
Obviously raising your rev limit depends upon your risk tolerance and engine mods. I have dual valve springs and set my rev limit at 7100. That way I can quickly change my shift points at the track by only changing the Full Throttle Shift RPM.
Also, you can set a much lower rev limit for just Park/Neutral, which helps overrev in those positions.
Obviously raising your rev limit depends upon your risk tolerance and engine mods. I have dual valve springs and set my rev limit at 7100. That way I can quickly change my shift points at the track by only changing the Full Throttle Shift RPM.
Also, you can set a much lower rev limit for just Park/Neutral, which helps overrev in those positions.
I ran across some stuff on the HP Tuners forum that I am going to try today. I am going to log output shaft rpms to calculate the actual mph that the trans thinks it is seeing and use those values to command the shift.
Trending Topics
Moderator
Joined: Aug 2010
Posts: 7,323
Likes: 529
From: Ann Arbor, MI
I am unable to help anyone from Ohio State! 
)
Actually congrats on your perfect season! Too bad the team now has to pay for the mistakes of others.
I don't know if this forum allows its, but if you could post your tune and a log file from HP Tuners, I would be happy to look at it. I'm sure experts like 01ssreda4 would figure it right out. If you cannot upload the files here, you can email them to me at ted -at- vedit -dot- com.
Ted.
)Actually congrats on your perfect season! Too bad the team now has to pay for the mistakes of others.
I don't know if this forum allows its, but if you could post your tune and a log file from HP Tuners, I would be happy to look at it. I'm sure experts like 01ssreda4 would figure it right out. If you cannot upload the files here, you can email them to me at ted -at- vedit -dot- com.
Ted.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
Pretty old post left hanging by the OP.
Anyway, this worked for me.
http://www.hptuners.com/forum/showthread.php?t=27981
I used the spreadsheet provided and found it to work well.
Ron
Anyway, this worked for me.
http://www.hptuners.com/forum/showthread.php?t=27981
I used the spreadsheet provided and found it to work well.
Ron
