Hot Rod Forum banner
1 - 17 of 17 Posts

·
Registered
Joined
·
131 Posts
Discussion Starter · #1 ·
I have a 4L65E GM transmission behind a Chevy 350 in a 67 chevelle and it is shifting late and hard. All new equipment. We have tried to adjust the TPS to deal with the problem but can’t get it right. We have not attempted to mess with the programming yet.
We have a 2400 to 2800 torque converter in it because that is what the GM dealer said I should get. From what I have read that might be a little high? Not sure if that could contribute to the shifting problem.
Looking for help with this shifting issue. I assumed that the factory tuning would suffice for street use. I think I either have a flakey TPS or the tuning isn’t right or worst case I have a lemon trans.

Hopefully someone here can help with external solution or program calibrations that work with this configuration.

Thanks.
 

·
Administrator
Joined
·
10,122 Posts
What transmission controller is used?

The 4L65E only shifts as the inputs from the controller tell it. Is this 4L65E a fresh unit? The converter stall speed does not affect shift timing.
 

·
Registered
Joined
·
131 Posts
Discussion Starter · #3 ·
What transmission controller is used?

The 4L65E only shifts as the inputs from the controller tell it. Is this 4L65E a fresh unit? The converter stall speed does not affect shift timing.
The controller also came with the transmission and is a GM SuperMatic controller GM (19332775)
all equipment is new.
 

·
Registered
Joined
·
131 Posts
Discussion Starter · #5 ·
Also, your will need a way to read what your tps is doing exactly. Just guessing at this could be your problem.

What carb are you running? How is the sensor attached?
Not sure how it is attached. The guy who put this together is a veteran car builder but rarely uses electronic transmissions. The controller kit came with tps sensor and mounting hardware. It’s on a holley 650 I think. I have not looked at it yet but I have no reason to believe it is not installed well. I’ll be able to mess with it this weekend. I’m planning to check voltages on the tps and look everything over. I might even be able to look at the program calibration provided I can get the app installed and everything hooks up and works.
 

·
Registered
Joined
·
131 Posts
Discussion Starter · #7 ·
You‘re going to have that controller set up for your combination.
How could it know gear ratio,drive by wire or tps,pwm or off / on lock up and other parameters when it could be installed in any car.
it’s advertised as plug & play but I hear ya. It may require some programing tweaks. I’m looking at the manual now. I can see in the manual where you can specify tire size and some other specs and I’m sure I can handle that once I get in there. But there are a lot of other parameters in the calibration that are Greek to me. Maybe the easy stuff is enough to get it rolling and I hope so. But if I have to mess with pressure and rpm curves and other stuff I won’t be able to do much more than guess.
But I was expecting the tps to be the biggest source of shifting info so I thought something must be wrong. First time I have ever messed with an ele trans. Makes me wonder how the old ones without computers ever worked.
 

·
Registered
Joined
·
95 Posts
it’s advertised as plug & play but I hear ya. It may require some programing tweaks. I’m looking at the manual now. I can see in the manual where you can specify tire size and some other specs and I’m sure I can handle that once I get in there. But there are a lot of other parameters in the calibration that are Greek to me. Maybe the easy stuff is enough to get it rolling and I hope so. But if I have to mess with pressure and rpm curves and other stuff I won’t be able to do much more than guess.
But I was expecting the tps to be the biggest source of shifting info so I thought something must be wrong. First time I have ever messed with an ele trans. Makes me wonder how the old ones without computers ever worked.
Install any parameters you can and go from there.
 

·
Registered
Joined
·
131 Posts
Discussion Starter · #9 ·
Install any parameters you can and go from there.
Ok, will do. There are other issues going on like having to remove the dash again because the ac is not working correctly so even though I can work on the calibration this weekend I might not be able to drive it. It’s always something. But I have to at least go through the motions with the calibration so I can work through any problems I have with getting that stuff to work since I have not attempted it yet. Not that anything could possibly go wrong...

thanks.
 

·
Registered
Joined
·
131 Posts
Discussion Starter · #10 · (Edited)
Ok, will do. There are other issues going on like having to remove the dash again because the ac is not working correctly so even though I can work on the calibration this weekend I might not be able to drive it. It’s always something. But I have to at least go through the motions with the calibration so I can work through any problems I have with getting that stuff to work since I have not attempted it yet. Not that anything could possibly go wrong...

thanks.
Today I connected a laptop to the transmission and was able to set the tire size and rear end gear ratio. Did not get to drive it yet. Other settings were basically curve charts that can be adjusted to change shifting characteristics. One was based on pressure and the other based on TPS position.
Only the basic feature was enabled. Other features like breaking, manual shifting, performance mode, overdrive cancellation etc were all disabled.
The tire size was only 1/2” off and the gear ratio was something like 3.5 and we changed that to be 3.08 per the rear end in the car.
It’s hard to believe that is enough to make a difference but hopefully it is. If not then I guess we will have to play with the curves. The instructions say that modifications most likely will not be necessary but if the tire size and gear ratio changes don’t fix it then I guess we are a special case for some reason.
I think the TPS curves for the shift points are fairly straight forward and I could tweak those but I don’t know how I would adjust the pressure curves. Don’t know exactly what that means yet and therefore I don’t know what changes to make.
Got to drive it first though!
It would have been nice if the manufacturer had provided a bit more detail to help with tuning and troubleshooting but adequate documentation is not a concern of most venders today.
There are a number of transmission controllers on the market today that do offer multiple “out of the box” tunings based on defined car configurations but my controller software did not come with any.
 

·
Registered
Joined
·
131 Posts
Discussion Starter · #11 ·
Also, you will need a way to read what your tps is doing exactly. In real time.
Just guessing at this could be your problem.

What carb are you running? How is the sensor attached?
I need to go back and test the tps voltages. Last time I went over there I did not have pins to stab the wires with and could not measure the voltages.
So with this in mind, what voltages should I see from idle to full throttle? The only info I see in my instructions is that one of the wires is a 5v reference wire and that the voltage on the output should increase as you move from idle to full throttle. So assuming the max range is 0v to 5v, what exactly am I expecting the voltage to be at idle? Probably not zero but maybe .5v to .6v ? I have seen some other folks setting it about there on other vehicles.
And full throttle should be maybe 4.5v to 4.8v ?

Does that sound right?
 

·
Registered
Joined
·
131 Posts
Discussion Starter · #12 ·
I finally found the time to check the throttle position sensor and it was off a bit. We are thinking that the first time it was set the throttle must have been in fast idle position. I was able to set it to .5v at regular idle and confirmed 4.3v at full throttle. This combined with the earlier programming in the tire size and gear ratio seems to have helped. It’s still rough going from 1st to 2nd but 3rd and 4th shifts are smooth. Maybe it will smooth out over time. I am now told that I can reset the transmission controller after driving it some and maybe it will retune itself a little better. Don’t know for sure but I might try that at some point after some break in period. If it’s still rough after that I think I know how to adjust the pressure curve values now.

I drove the car about 20 miles today for the first time. It’s much nicer than I expected. Smooth and tight. Sounds great and scoots when you spur it. Going to be fun once the transmission smoothes out.

The speedometer is whacked out though. It’s way to sensitive to actual speed. 35 actual mph will peg the needle all the way to the right. What’s a car without one more problem, right?
Time to go find the instructions for the gauge cluster...
 
  • Like
Reactions: ExcellenceAuto

·
Registered
Joined
·
445 Posts
Since the transmission requires a correct signal from the VSS (Vehicle Speed Sensor) in order to know when to shift, that may be causing your problems. I vaguely remember that there are different senders, so you need to be sure its correct. If that fails, you might consider approaching the dealer and see if he would put a factory scanner on it .....since he sold it to you and its advertised as "plug and play". Not sure, but I think the dealer can make corrections but you may need a different "pulse generator" to correct the issue. Below is an attachment thats not exactly related, but it does point out that there are electronic ways to fix your problem.
616607


Not sure if the following article will help shed some light or not, but I have to leave and don't have too much time to reread it.
616608

616609

616610

616611
 

·
Registered
Joined
·
131 Posts
Discussion Starter · #15 ·
Ok, it’s been a while but now I’m cooking with gas! I hooked a laptop to the transmission such that I could drive and tweak. First, not being sure of the rear end ratio i ran a gps speedo app on my phone and compared the speed with that of the transmission TCU. They matched which tells me the gear ratio i entered into the TCU configuration is correct. For those who are interested it’s a 3.08 rear end (67 Malibu stock with 283/power glide). In the TCU diagnostic/tuning app I monitored the throttle position sensor, rpm, speed, gear, and was also able to watch the shift curves and the tps/speed indicator ball in the chart in real time as I drove. What I observed was that the ball did not want to cross the shift lines on the chart. It was hovering just below the line no matter how fast I went and would not cross the shift line to go into 2nd until I let off the gas. Letting off the gas moves the ball back to the left (tps signal is reduced) where it will inevitably cross the shift curve line due to the shape of the curve. The reason for the ball not crossing the line has to do with the relationship between your throttle position sensor position and the speed at which the car is moving at any given time. This relationship will be different for nearly every vehicle due to differences in sensor adjustment, engine power, gears and weight and maybe a few hundred other things.
So i adjusted the 1st-to-2nd shift line down in the chart by modifying the values in the curve table and now the ball crosses the shift line and the shift occurs. I now know how to tune this part of the program. It will take some time to dial it in just right as you have to tweak-drive, tweak-drive over and over till you get it right. It will need to behave properly across the full range of driving habits wether you are laid back or aggressive so there is some work to be done over the entire range of the TPS.
Then there are 2 more shifts to work out too. But they are not to bad as is.
There is also shift pressure. Right now the shifts are pretty hard. I didn’t really know anything about this until today and I figured out how to adjust this as well. By increasing the Current settings in the Current vs TPS table you can soften the shifts.
In both tables when making changes I made sure to make small changes each time then retest. You don’t want to get something so far out of wack that you get into trouble. And note that you want shifts to be firm but comfortably so (no whiplash required).
The last thing I need to figure out is the torque converter lockup. The default curves there don’t look to good based on what I have read. The default lockup curve goes up to 255 MPH which is a little fast on the roads I drive. I’m still reading up on TCC lockup and I’ll be able to deal with that after I get the shifting nailed down.
The TCU app has a data logging feature that is very powerful. It will plot numerous types of data including the TCC lockup so I’ll be able to see exactly what is going on and from that I’ll be able to tune the TCC lockup table.

Anyway, I hope this is helpful and interesting. I wanted to share my findings since it is darn near impossible to find good detailed info online about this. I’ll report back again in a week or so hopefully with some final results.
 

·
Registered
Joined
·
131 Posts
Discussion Starter · #16 ·
Since the transmission requires a correct signal from the VSS (Vehicle Speed Sensor) in order to know when to shift, that may be causing your problems. I vaguely remember that there are different senders, so you need to be sure its correct. If that fails, you might consider approaching the dealer and see if he would put a factory scanner on it .....since he sold it to you and its advertised as "plug and play". Not sure, but I think the dealer can make corrections but you may need a different "pulse generator" to correct the issue. Below is an attachment thats not exactly related, but it does point out that there are electronic ways to fix your problem. View attachment 616607

Not sure if the following article will help shed some light or not, but I have to leave and don't have too much time to reread it. View attachment 616608
View attachment 616609
View attachment 616610
View attachment 616611
Thanks for the article. I finally got the Classic Instruments speedo calibrated. So the sensor is correct. The shifting problem is also now understood and is just a matter of tuning. Not knowing anything about this when I started and reading that the transmission should have been a “plug & play” install I had no idea that the programming of the transmission would be so necessary. Someone else mention here that It would be necessary and that person was surely right ( @3w coupe ). I think the 4L65e trans is typically used in trucks maybe so bigger, heavier, lower gears etc. All makes a big difference.
 

·
Registered
Joined
·
131 Posts
Discussion Starter · #17 ·
Ok this will my final entry on this topic. Tuning is near complete and shifting is nice and smooth. The whole problem with my experience here was caused by an incorrect default tune from GM. The TCU Supermatic software app came with two default tunes. One for normal use and one for sport (performance) use. In my case both tunes were the same and they both were the more aggressive tune. Granted most folks will probably need or want to tweak the tune some from the default values but in my case the performance tune was far from good for normal driving and it was the only option I had. I ended up tuning far away from that tune to get it where I wanted it. It’s now properly meek and mild for casual driving and still gives you an aggressive tendencies option when you get more serious with the throttle. I guess if you are racing and need the extra authority on the bottom end then you want the performance tune. If you spend your life on the street the tune for that is quite different. The documentation is not the most helpful and has errors in it but if you think your way through the tuning process and take your time and make small adjustments between testing you’ll figure it out.
Hopefully GM is shipping the right tunes out now. I bought my stuff two years ago. There is a sample screenshot of the shift pressures in the documentation that apparently is the correct curves for the “A” program but that may not match what is actually in the application and the transmission when you get it. I modeled mine after that screenshot and that created a much better starting point.

Hope this helps someone. As soon as I figure out how I may post some pics of my tune.
 
  • Like
Reactions: lmsport
1 - 17 of 17 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top