VERY FRUSTRATED -Continued Tranny Problems after Diff swap
Thread Starter
Heel & Toe
Joined: May 2005
Posts: 21
Likes: 1
VERY FRUSTRATED -Continued Tranny Problems after Diff swap
I've had lots of valuable input from this forum that I've shared with my programer. Thought we had it fixed but had to abort a club trip this morning. This all began with my swap of the stock diff (auto trans) to 3:43. I've been to the programer 3 times now. Your input about TCC tables, timing retard at shift etc have been considered or tried. My programer is actually talking to the LS1 author (he says). The car runs absolutely fantastic around town. When I get on the freeway for 15 minutes or more, tranny temp gets to 195-203 and I begin to notice the RPM creeping up at cruise set speed. This is the sign that the problem is back. When pulling away from stop I get violent gear shifts. After the last programing change I notice that the violent shifts are not as hard as they were prior to the last programing change. For this reason I feel that we might have made some progress. I am frustrated to the point that I may give up on this 42K mile transmission. In any case, I'll make another trip to the programer tomorrow (Monday). Any additional input is greatly appreciated.
Team Owner
Joined: Apr 2001
Posts: 54,204
Likes: 180
From: S.W. Ohio. . . . . . NRA Life Member
generally this is due to incomplete programing.
But one thing mentioned - should not be happening if the only problem is programing.. and that is this:
this would not be happening if the problem was solely due to incomplete programing. There would be no "slipping"... just the hard shifting after running on the highway. The only raising of RPM that would occur with bad programing would be only due to the torque converter unlocking... but that would account for only 300 to 400rpm in 4th OD. And it wouldn't "creep" up, but would be almost an instantaneous RPM change.
There may be another problem here.
Are you certain the tranny is fluid fill is to spec? If you didn't know... checking the tranny fluid level is done with the engine running and the tranny temp within a certain range.
.
But one thing mentioned - should not be happening if the only problem is programing.. and that is this:
When I get on the freeway for 15 minutes or more ... I begin to notice the RPM creeping up at cruise set speed.
There may be another problem here.
Are you certain the tranny is fluid fill is to spec? If you didn't know... checking the tranny fluid level is done with the engine running and the tranny temp within a certain range.
.
Thread Starter
Heel & Toe
Joined: May 2005
Posts: 21
Likes: 1
Tranny Frustration continued -Answers to your questions
No codes have appeared or any problem indicators. I did not not change the TC. The car is a 2001 and has 42K miles. Not sure about the differential as I bought it used but feels tight and runs quiet. I will ask about gear scaler in the PCM. He is using LS1 Edit.
With regard to Mercury's point, maybe creeping isn't the best description. It normally gets my attention because of the feeling of a downshift out of OD. When I back of pedal then reapply power it 100 to 200 above normal which is 2100 at 70 MPH. I normally (manually) shift to 3rd, accelerate to 80 then manaully shift to 4th. It will usually settle back in at 2100 although it is easy to get it to slip up again. Of course when I come to stop the hard shifting is back until the components cool off, then everything is perfectly normal.
As to the fluid level, I have never checked it. The operator manual says if there is no evidence of leak, no need to check. At certain times during this ordeal I have had burned smell and feel like the fluid would smell burned. I'm afraid to change it for fear of losing all functionality.
Think that's all the questions, sorry to be so long winded.
PR
With regard to Mercury's point, maybe creeping isn't the best description. It normally gets my attention because of the feeling of a downshift out of OD. When I back of pedal then reapply power it 100 to 200 above normal which is 2100 at 70 MPH. I normally (manually) shift to 3rd, accelerate to 80 then manaully shift to 4th. It will usually settle back in at 2100 although it is easy to get it to slip up again. Of course when I come to stop the hard shifting is back until the components cool off, then everything is perfectly normal.
As to the fluid level, I have never checked it. The operator manual says if there is no evidence of leak, no need to check. At certain times during this ordeal I have had burned smell and feel like the fluid would smell burned. I'm afraid to change it for fear of losing all functionality.
Think that's all the questions, sorry to be so long winded.
PR
Team Owner
Joined: Apr 2001
Posts: 54,204
Likes: 180
From: S.W. Ohio. . . . . . NRA Life Member
Originally Posted by pmruss
maybe creeping isn't the best description. It normally gets my attention because of the feeling of a downshift out of OD. When I back of pedal then reapply power it 100 to 200 above normal which is 2100 at 70 MPH. I normally (manually) shift to 3rd, accelerate to 80 then manaully shift to 4th. It will usually settle back in at 2100 although it is easy to get it to slip up again. Of course when I come to stop the hard shifting is back until the components cool off, then everything is perfectly normal.
there's a trick you can try to see of it's strictly programing or not... and that's to clear all codes... and then drive exclusively in "3".
and not checking the tranny fluid level is crazy guy !!!
It's not all that difficult to do:If you are going to check the trans with the car on stands, make sure it is high enough for you to safely move and work while the exhaust system is at operating temperature. Start the engine and, using the "gauges" button on the driver information center (DIC), put transmission temperature on the IPC display. Run the engine until the trans temp is between 86o and 122oF. Apply the brakes and shift into each gear for a few seconds, then shift back to park.
Set the parking brake, leave the engine running and crawl under the car. Position a drain pan under the fill plug area and remove the plug. If fluid dribbles out or is right at the bottom of the fill hole, your transmission is full. If fluid leaks profusely, it was overfull and you should allow the excess ATF to drain into the pan. If no fluid comes out you will (need to) add more...
If you need more fluid, add enough to bring the level up even with the bottom of the fill plug hole, replace the transmission fluid fill plug and shut off the engine. Your fluid check is complete. If a large addition of fluid was required, there is a leak somewhere that needs to be repaired. If the leak is not obvious, see the Service Manual for information on leak detection. Admittedly, checking the C5 ATF can be an awkward, messy operation. Before you do it, get the car up in the air and visualize the procedure.
by Hib Halverson
Le Mans Master
Joined: Jul 2002
Posts: 7,370
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From: Slave to the evil empire
Cruise-In V Veteran
St. Jude Donor '04
[QUOTE=Mike
and not checking the tranny fluid level is crazy guy !!! It's not all that difficult to do:[/QUOTE]
If your tranny fluid is burnt then continuing to run it will only burn up your transmission.
and not checking the tranny fluid level is crazy guy !!!
It's not all that difficult to do:[/QUOTE] If your tranny fluid is burnt then continuing to run it will only burn up your transmission.
Burning Brakes
Joined: Mar 2003
Posts: 966
Likes: 43
From: Lansing MI
Unfortunately, based on what he describes I bet it's too late to add fluid. If your anywhere near the midwest, get ahold of Crashed94 or FLP and get it fixed right. I'd also look for a new tuner! JEff
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Drifting
Joined: Sep 2002
Posts: 1,947
Likes: 0
From: Howell MI.
Tcc
It sounds like the converter is un locking due to misfire and when it does this after a while it will put the trans into limp mode or shift extremly hard .
I have done some things to stop this ,but I will not recommend what i did .
My choice !
If you converter is unlocking it will feel like a small downshift and feel like it is slipping
Misfire will cause this.
Have you added a cam also ?
Do a search and find out what most have done.
The other forum has a section on automatic transmissions
When you need a new a4 built ,read the above post .
John Sr.
I have done some things to stop this ,but I will not recommend what i did .
My choice !
If you converter is unlocking it will feel like a small downshift and feel like it is slipping
Misfire will cause this.
Have you added a cam also ?
Do a search and find out what most have done.
The other forum has a section on automatic transmissions
When you need a new a4 built ,read the above post .
John Sr.
Thread Starter
Heel & Toe
Joined: May 2005
Posts: 21
Likes: 1
Tranny cured - thanks to you guys!!!
I took the latest input from you guys to my programer and he got an "OH YEAH" look on his face. The problem was the gear scaler/PCM. It is running perfect again, thanks to guys. I will check the fluild this weekend.
Many,many Thanks!!
Many,many Thanks!!
Pro
Joined: Feb 2004
Posts: 657
Likes: 1
From: michigan
Originally Posted by pmruss
I took the latest input from you guys to my programer and he got an "OH YEAH" look on his face. The problem was the gear scaler/PCM. It is running perfect again, thanks to guys. I will check the fluild this weekend.
Many,many Thanks!!
Many,many Thanks!!
Heel & Toe
Joined: May 2021
Posts: 17
Likes: 1
Piggy back
I know this is an old thread. Did the 3.42 swap then started having rev limiter issues with it bouncing before shift. Fixed it somewhat with my tuner. Now for some reason when I start driving the car, you can hear an audible difference in RPM. If I get on it when it does that it prevents it from hard shifting. If I don't, it'll hard shift. If I turn the car off, it goes away and I'm good until it decides to do it again. What am I missing?
Melting Slicks
Joined: Jul 2004
Posts: 3,294
Likes: 480
From: Brea CA
I know this is an old thread. Did the 3.42 swap then started having rev limiter issues with it bouncing before shift. Fixed it somewhat with my tuner. Now for some reason when I start driving the car, you can hear an audible difference in RPM. If I get on it when it does that it prevents it from hard shifting. If I don't, it'll hard shift. If I turn the car off, it goes away and I'm good until it decides to do it again. What am I missing?
Now about a year ago I installed a 3.42 on my 2002 having it tuned to support the diff change. Ended up having some hard shifts from 1st to 2nd. Code I had was P1870 which is related to the torque converter lockup. Another item to note is the trans temp after running a bit was over 217*F. It got to that temp fairly quickly.
After some diagnostics it was determined that my car had a failing torque converter. My car has 225k on it. So I did the best thing for it, had the trans rebuilt. At this mileage the shop indicated that the clutches were worn and one of the drums needed replaced. Have it all back together and running ok so far. Now I have put about 70 miles on it so far and have not seen the trans temp climb up to where it had been.
I think with my car, the torque converter was failing prior to putting in the 3.42 and doing that brought the issue to the surface.
Gary
Race Director
Joined: Oct 2004
Posts: 12,861
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Failing torque converter clutches (TCC) ruined many 700R4s. Most know that the 700R4 was the father of the 4L60E. I had a TCC fail in the 700R4 of my 1985 IROC-Z. It was stuck in first gear, and when I drove it with the shifter in O/D, under light throttle, it would slowly rev up to almost 5,500rpm before the governor forced a shift to 2nd gear, which made the rear tires chirp pretty good. When I pulled the pan, the 1" diameter magnet was about 3-1/2" diameter full of steel shavings. GM REALLY had a Helluva time getting the bugs out of that trans. Most of it was by the seat of their pants. Actually, OUR pants, as we were all guinea pigs.......
Last edited by grinder11; Mar 2, 2025 at 03:22 PM.