Torque converter lock and unlock
Thread Starter
Burning Brakes
Joined: Jun 2006
Posts: 933
Likes: 0
From: St. Paul MN
Torque converter lock and unlock
I've recently installed a Yank SS3600 converter and 3.42 diff (along with my heads/cam etc. etc.). When I drive down the highway the converter will lock and then a few mins later unlock....as I cruise at a constant velocity. A couple of details:
1)The car has not been tuned yet (looks like I'm in line to have that done next week).
2)I'm not 100% sure of the trans fluid level but I suspect I'm very close.
3)On a 30-40min cruise the trans temp will reach ~195 (I do have a transmission cooler installed)
I've been assuming that it had to do with the fact that the computer hasn't been told about the new converter and gears.
Any thoughts?
Thanks!
1)The car has not been tuned yet (looks like I'm in line to have that done next week).
2)I'm not 100% sure of the trans fluid level but I suspect I'm very close.
3)On a 30-40min cruise the trans temp will reach ~195 (I do have a transmission cooler installed)
I've been assuming that it had to do with the fact that the computer hasn't been told about the new converter and gears.
Any thoughts?
Thanks!
Burning Brakes
Joined: Aug 2006
Posts: 956
Likes: 12
From: Eastern PA
If your car has not been tuned, I would tell you that it will run kinda weird until it is. Remember that all of the stock parameters would still be in play. These parameters include your shift points, fan op temps,etc, etc. Your tranny is still running like it had all of the stock parts to it and ofcourse it doesn't. With the 3600 SC and new gears versus the old (which I guess would have been either the 2.73 or 3.15) your still running with those old shift points. The stock stall on the C5 I think was 1600 or so (could be 1900 but somewhere in there) Once you have the car tuned, the shift points, fan op temps and a multitude of other items will be adjusted to compliment your upgrades and provide the proper operation of the car.
Thread Starter
Burning Brakes
Joined: Jun 2006
Posts: 933
Likes: 0
From: St. Paul MN
If your car has not been tuned, I would tell you that it will run kinda weird until it is. Remember that all of the stock parameters would still be in play. These parameters include your shift points, fan op temps,etc, etc. Your tranny is still running like it had all of the stock parts to it and ofcourse it doesn't. With the 3600 SC and new gears versus the old (which I guess would have been either the 2.73 or 3.15) your still running with those old shift points. The stock stall on the C5 I think was 1600 or so (could be 1900 but somewhere in there) Once you have the car tuned, the shift points, fan op temps and a multitude of other items will be adjusted to compliment your upgrades and provide the proper operation of the car.
Yes, I upgraded from a 2.73
Burning Brakes
Joined: Mar 2003
Posts: 1,044
Likes: 5
From: Canton MI
i did add a 3000 yank converter that netted me the same 60' as the stock. I have asked about tuning but have never heard a straight answer. I also have 3.42's but shift points were adjusted at time of install(before TC).
Team Owner
Joined: Apr 2001
Posts: 54,204
Likes: 180
From: S.W. Ohio. . . . . . NRA Life Member
Clear out the code and drive in "3" until you get a reprog.
http://mikemercury.home.att.net/342.htm
Advanced
Joined: Oct 2002
Posts: 97
Likes: 0
From: Fort Mill Sc
Yes, I had the same problem when I installed my Vig 2800. I had my tuner modify my misfire tables. This fixed the problem. I don't remember the details, but your tuner should be familia r with this.
r with this.
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Pro
Joined: Mar 2007
Posts: 600
Likes: 11
From: Wilmington NC
Went from 3.15 to 3.73 and installed the Yank SS3200.
It drove fairly awkward until I took it to get tuned. My shift points were off, the MPH was off, and it refused to go into gear (2-3, or 3-4) at WOT.
A tune will adjust the torqe converter schedules for lock and unlock: examples.
You can adjust at which MPH it will unlock in a certain gear under throttle to downshift.
You can do the reverse and program it to not downshift past a certain RPM or MPH and just ride out the gear.
You will also reprogram at which RPM or MPH the transmission will shift up as well.
Take notes on what MPH the car goes at the RPM you want it to shift at. Input these into your new tune. I had to lower all of my speeds with higher gears for the obvious reasons.
It drove fairly awkward until I took it to get tuned. My shift points were off, the MPH was off, and it refused to go into gear (2-3, or 3-4) at WOT.
A tune will adjust the torqe converter schedules for lock and unlock: examples.
You can adjust at which MPH it will unlock in a certain gear under throttle to downshift.
You can do the reverse and program it to not downshift past a certain RPM or MPH and just ride out the gear.
You will also reprogram at which RPM or MPH the transmission will shift up as well.
Take notes on what MPH the car goes at the RPM you want it to shift at. Input these into your new tune. I had to lower all of my speeds with higher gears for the obvious reasons.
Thread Starter
Burning Brakes
Joined: Jun 2006
Posts: 933
Likes: 0
From: St. Paul MN
Is this what is happening?
The computer tells the transmission to lock the converter. It then sees that for the given RPM the vehicle is moving too slow and assumes the transmission must be slipping.
Ok that explains the 1870 code, but why does the transmission come out of lock up?
The computer tells the transmission to lock the converter. It then sees that for the given RPM the vehicle is moving too slow and assumes the transmission must be slipping.
Ok that explains the 1870 code, but why does the transmission come out of lock up?
Pro
Joined: Mar 2007
Posts: 600
Likes: 11
From: Wilmington NC
Is this what is happening?
The computer tells the transmission to lock the converter. It then sees that for the given RPM the vehicle is moving too slow and assumes the transmission must be slipping.
Ok that explains the 1870 code, but why does the transmission come out of lock up?
The computer tells the transmission to lock the converter. It then sees that for the given RPM the vehicle is moving too slow and assumes the transmission must be slipping.
Ok that explains the 1870 code, but why does the transmission come out of lock up?
You will not have to explain in explicit details what the car is doing. A good tuner only needs to hear these words *Gears* *Converter* and they will just ask you what size for each. As Emeryl would say "Bam!"
Team Owner
Joined: Apr 2001
Posts: 54,204
Likes: 180
From: S.W. Ohio. . . . . . NRA Life Member
Le Mans Master
Joined: Mar 1999
Posts: 6,029
Likes: 85
From: Palm Coast, FL
I have the same prob. with my SS3200 with it keeps locking and unlocking, even after the tune...I am NOT going to say who did the tune and start a WAR!!!
I haven't gotten a street tune, since replacing the cam and doing heads and Intake, TB etc. the current tune is a dyno tune and is just well enough to drive it. I wanted to put in a bigger MAF and CAI and 160 Stat before letting him re-tune, I understand the CAI, stat and MAF will require another tune so I really don't want him to have to do it twice.
Last edited by Rob Petyo; Jul 17, 2008 at 09:34 PM.
Advanced
Joined: Oct 2002
Posts: 97
Likes: 0
From: Fort Mill Sc
I was not getting a check engine light, and it was not misfiring. The smaller diameter converter allows enough crank jerk to make the pcm think it is misfiring. It's not constant enough to set a DTC, but will cause the TCC to lock and unlock. Adjusting the misfire tables, reduces the sensitivity. I got the new misfire table from LS1 Tech. Have not had an issue in 2 years. Hope this helps.
