Thread: 4T65E Hard Shift-Solution

Does the P1811 code indicate that this the pcm is the issue? I am throwing that code. Further, the problem did not exist one day and then does the next.

First, just be aware than I am no expert on transmissions. I do get the basic logic of how they work, and have read up a lot on this problem by now.

In short, no the 1811 code doesn't actually tell you anything about whether the PCS is working or not. Its description in code lists is "Max Adapt Long Shift." Basically, the car's computer keeps track of how long it takes to get from one gear to the next. (I believe it is supposed to be .65 seconds or less). If the computer detects too many long shifts (> .65 sec) it will send full transmission fluid pressure into the shifts. When it does this you feel it as a hard shift / bump shift.

The reason it does this is actually to protect the transmission. All smooth shifts (whether in an auto or manual trans) involve momentary clutch slipping between gears. The more slip the smoother the shift. But the more slip the more wear and heat are created. The full line pressure / hard shifting basically eliminates slip - helps avoid completely burning up clutches and overheating the trans.

Now, the PCS enters the picture because it is the thing that controls the line pressure for the shifts. Every time you drive the line pressure is going up and down in response to what all else is going on - e.g. at light throttle line pressure tends to be lower. The computer is watching what all the car is doing and is commanding the PCS to give a certain amount of line pressure for each shift.

Apparently it is the case that many of these PCSs had problems - they get gunked up and don't work right anymore, and/or get shorted out by high trans temps. If the PCS does get messed up you can get the hard shifts for various reasons.

But, it is also the case that the PCS might be doing exactly what it is supposed to. If your trans is worn and there is too much slipping between gears the computer will see it, it will command full line pressure, the PCS will respond the way it should, and the 1811 code will get set.

The only way that you can really find out is by having a highly experienced transmission tech put the car on a very fancy scanner where all of the inputs and outputs and pressures and etc. can be monitored. But even that doesn't always seem to help.

If the computer does detect a PCS malfunction, that does have its own code - P0746 (PCS Performance). I just don't know what kinds of conditions or events trigger that code.

Hope that helps.

Originally Posted by jhs3eva

First, just be aware than I am no expert on transmissions. I do get the basic logic of how they work, and have read up a lot on this problem by now.

In short, no the 1811 code doesn't actually tell you anything about whether the PCS is working or not. Its description in code lists is "Max Adapt Long Shift." Basically, the car's computer keeps track of how long it takes to get from one gear to the next. (I believe it is supposed to be .65 seconds or less). If the computer detects too many long shifts (> .65 sec) it will send full transmission fluid pressure into the shifts. When it does this you feel it as a hard shift / bump shift.

The reason it does this is actually to protect the transmission. All smooth shifts (whether in an auto or manual trans) involve momentary clutch slipping between gears. The more slip the smoother the shift. But the more slip the more wear and heat are created. The full line pressure / hard shifting basically eliminates slip - helps avoid completely burning up clutches and overheating the trans.

Now, the PCS enters the picture because it is the thing that controls the line pressure for the shifts. Every time you drive the line pressure is going up and down in response to what all else is going on - e.g. at light throttle line pressure tends to be lower. The computer is watching what all the car is doing and is commanding the PCS to give a certain amount of line pressure for each shift.

Apparently it is the case that many of these PCSs had problems - they get gunked up and don't work right anymore, and/or get shorted out by high trans temps. If the PCS does get messed up you can get the hard shifts for various reasons.

But, it is also the case that the PCS might be doing exactly what it is supposed to. If your trans is worn and there is too much slipping between gears the computer will see it, it will command full line pressure, the PCS will respond the way it should, and the 1811 code will get set.

The only way that you can really find out is by having a highly experienced transmission tech put the car on a very fancy scanner where all of the inputs and outputs and pressures and etc. can be monitored. But even that doesn't always seem to help.

If the computer does detect a PCS malfunction, that does have its own code - P0746 (PCS Performance). I just don't know what kinds of conditions or events trigger that code.

Hope that helps.

Great explanation! It is nice to see thorough explanations to issues and solutions that involve more than just 2 sentence explanations loaded with sarcassim. BTW-Just passed 7,000 miles on my transmission with the coolers and shift kit with no hard shifts. Thanx.

jbamonte, when you pulled your accumulator what kind of shape was the accumulator gasket in? How about the piston seals? Did that kit come with new gasket and piston seals or were the old ones perfectly good to reuse?

The Transgo shift kit doesn't come with these and I don't know if I need them.

For anyone else looking at this job, there is akit by Thrasher what comes with new gasket and piston seals. I'm kind of wishing I ordered that one... (but it is also $90.)

Originally Posted by jhs3eva

jbamonte, when you pulled your accumulator what kind of shape was the accumulator gasket in? How about the piston seals? Did that kit come with new gasket and piston seals or were the old ones perfectly good to reuse?

The Transgo shift kit doesn't come with these and I don't know if I need them.

For anyone else looking at this job, there is akit by Thrasher what comes with new gasket and piston seals. I'm kind of wishing I ordered that one... (but it is also $90.)

\\


I installed the shift kit about a year ago and the accumulator gasket was perfectly reusable. I carefully separated the two halves of the accumulator once the bolts were out, it easily came apart with the gasket in perfect shape and very reusable. The piston seals on mine were perfect, no issues. My gaskets were in excellent shape but as I have said before, my transmssion was never abused since new in 2001 and the fluid was changed at 45,000 miles (way too long BTW!), 65,000, 93,000, and again at 95/96,000 chasing the hard shift problem before I came across my solution.

jbamonte

Did you happen to get any Pictures of this setup with the cooler?