Torque Converter slippage (Help)

[GringoPete]

Does anyone here know anything about "Torque Converter Slippage"?

When i am at a complete stop and go to hit the gas the front end of my car shudders until i lighten up off the gas. At first i thought it was my worn tires which i replaced but it is still doing it. Doing a little research on the transmission in the 98 Lesabre i had found other people with this tranny having what is called "Torque converter problems/shudder" It only happens when at a complete stop. Other than that the tranny is very smooth.

[HotZ28]

Converter shudder does not happen when you first accelerate, normally that happens during T/C lockup. First, check Trans & motor mounts.

[GringoPete]

Originally Posted by HotZ28

Converter shudder does not happen when you first accelerate, normally that happens during T/C lockup. First, check Trans & motor mounts.

I'm assuming the motor mounts are fine as i drive all day without any jolting , motor shifting, or any other noises. Completely quiet and smooth going. Only from a complete stop if i give it a little too much gas. If i pull from a stop slowley it doesnt do it. Do you think it's the tires spinning out when i give it too much gas?

[BNaylor]

To start double check and inform us which autotransaxle you have. Should be the 4T65E GM RPO code MN3 or M15. Check the SPID label located on the spare tire cover.

Launch shudder can be cause by a flaky pressure control solenoid (PCS), a valve body issue or an internal hardware issue such as worn out clutch packs etc. Get it scanned with a trans capable scan tool and see if any slippage or long shift codes are stored. A few of these DTCs such as P1811 do not trigger the SES/CEL light but stores for retrieval if set.

Also, what is your mileage?

[GringoPete]

Originally Posted by BNaylor

To start double check and inform us which autotransaxle you have. Should be the 4T65E GM RPO code MN3 or M15. Check the SPID label located on the spare tire cover.

Launch shudder can be cause by a flaky pressure control solenoid (PCS), a valve body issue or an internal hardware issue such as worn out clutch packs etc. Get it scanned with a trans capable scan tool and see if any slippage or long shift codes are stored. A few of these DTCs such as P1811 do not trigger the SES/CEL light but stores for retrieval if set.

Also, what is your mileage?

My milage is 90,000 . I'll get back to you on the Transaxle info.

[GringoPete]

Ok, I wasnt sure which number to copy so i took a picture. Too much trouble emptying my trunk everytime i need to access this info. Now i'll have it handy on my computer

[gquirk]

check the motor mounts as suggested, I had the same problem on my buick took it to a trans shop to get checked and it was the motor mounts going bad
you say you assume they are ok just get them checked
you seem to post alot of questions until you get the answer you want, start following some of the advice before you ask the next question

[HotZ28]

Do you think it's the tires spinning out when i give it too much gas?

Do you have traction control?

[GringoPete]

Originally Posted by gquirk

check the motor mounts as suggested, I had the same problem on my buick took it to a trans shop to get checked and it was the motor mounts going bad
you say you assume they are ok just get them checked
you seem to post alot of questions until you get the answer you want, start following some of the advice before you ask the next question

Will do. I'm going to bring it to my mechanic and have him take a look at it.

I only assumed that it wasnt the motor mounts because i've had motor mounts go on me in other cars and the symptoms were much different. But who knows? I did ask my mechanic about it before when i was picking up my wifes car and from what i explained to him he said its not the torque converter. He said if it was then the car would surge when i hit the gas and then stall kind of like when you put a manual transmission into gear and dont give it enough gas when you let off the clutch.opcorn:

Thanks for your suggestion(s).

[GringoPete]

Originally Posted by HotZ28

Do you have traction control?

No traction control.

[HotZ28]

Originally Posted by GringoPete

No traction control.

Well, that also eliminates the possibility of the EBTCM pulsation of the brakes during wheel spin, as a potential source!

[BNaylor]

Originally Posted by GringoPete

Ok, I wasnt sure which number to copy so i took a picture. Too much trouble emptying my trunk everytime i need to access this info. Now i'll have it handy on my computer

Thanks for the feedback. You have a 4T65E GM RPO Code MN3.

[Blue Bowtie]

Has the fluid been changed recently? Has it been changed regularly? Using an incorrect fluid can contribute to clutch slippage.

It might be beneficial to check the line pressure with a gauge and compare it to what the internal pressure sensor array is reporting to the PCM. Weak/dirty internal pressure sensors can report higher pressures, causing clutch slippage. Obviously, internal wear and hydraulic leakage can also result in slippage.

One potential (but not always definite) way to check for low pressure is to start in Range 1 and manually shift through the ranges. The PWM pressure control is basically bypassed when in manual mode, allowing full line pressure to operate the clutches and servos.

[GringoPete]

Originally Posted by Blue Bowtie

Has the fluid been changed recently? Has it been changed regularly? Using an incorrect fluid can contribute to clutch slippage.

It might be beneficial to check the line pressure with a gauge and compare it to what the internal pressure sensor array is reporting to the PCM. Weak/dirty internal pressure sensors can report higher pressures, causing clutch slippage. Obviously, internal wear and hydraulic leakage can also result in slippage.

One potential (but not always definite) way to check for low pressure is to start in Range 1 and manually shift through the ranges. The PWM pressure control is basically bypassed when in manual mode, allowing full line pressure to operate the clutches and servos.

Both the fluid and filter were changed almost two months ago. however, this is something that was occuring before that. I'll try manual shifting today when i go to work and i'll post back tonight to let you know what happens. Thanks for your help.

[BNaylor]

Did you ever get it scanned with a trans capable scan tool or at least one that can read out GM extended DTCs like P1XXX? As I might have mentioned earlier certain DTCs related to PCS and internal slippage may not trigger the SES/CEL light but are stored when a fault occurs.

Slips, Harsh Upshift or Garage Shifts, Launch Shudders, Flares, Erratic Shifts and Intermittent Concerns, DTC P1811 or P0748 Set (Replace Pressure Control Solenoid Valve Assembly) #00-07-30-002B - (07/19/2002)

Adapt Function
The 4T65-E transmission uses a line pressure control system, that has the ability to adapt line pressure to compensate for normal wear of the following parts:

The clutch fiber plates
The springs and seals
The apply bands
The PCM maintains information for the following transmission adaptive systems:

Upshift Adapts (1-2, 2-3 and 3-4)
The PCM monitors the automatic transmission input shaft speed (AT ISS) sensor and the vehicle speed sensor (VSS) in order to determine when an upshift has started and completed. The PCM measures the time for the upshift. If the upshift time is longer than a calibrated value, then the PCM will adjust the current to the pressure control (PC) solenoid valve to increase the line pressure for the next shift in the same torque range. If the upshift time is shorter than the calibrated value, then the PCM will decrease the line pressure for the next shift in the same torque range.

Steady State Adapts
The PCM monitors the AT ISS sensor and the VSS after an upshift in order to determine the amount of clutch slippage. If excessive slippage is detected, then the PCM will adjust the current to the PC solenoid valve in order to increase the line pressure to maintain the proper gear ratio for the commanded gear.

The TAP information is divided into 13 units, called cells. The cells are numbered 4 through 16. Each cell represents a given torque range. TAP cell 4 is the lowest adaptable torque range and TAP cell 16 is the highest adaptable torque range. It is normal for TAP cell values to display zero or negative numbers. This indicates that the PCM has adjusted line pressure at or below the calibrated base pressure.

Clearing Transmission Adaptive Pressure (TAP)
Updating TAP information is a learning function of the PCM designed to maintain acceptable shift times. It is not recommended that TAP information be reset unless one of the following repairs has been made:

Transmission overhaul or replacement
Repair or replacement of an apply or release component (clutch, band, piston, servo)
Repair or replacement of a component or assembly which directly affects line pressure
Resetting the TAP values using a scan tool will erase all learned values in all cells. As a result, the PCM will need to relearn TAP values. Transmission performance may be affected as new TAPs are learned. The PCM must also relearn TAP values when the PCM or the transmission is replaced.

Circuit Description
The transmission pressure is modified by an adaptive modifier which controls the shift execution time. This test checks the time required to accomplish the shift. If the shift takes longer than 0.65 seconds and the adaptive modifier cannot shorten this time, then a counter increases by one.

If the PCM detects a counter value of 2 during one trip, then DTC P1811 sets. DTC P1811 is a type C DTC.

Conditions for Running the DTC
The shift is adaptable.
The 1-2, the 2-3 or the 3-4 shift adapt cell has reached its limit.
Conditions for Setting the DTC
The 1-2, 2-3 or 3-4 shift is longer than 0.65 seconds, twice in one trip.

Action Taken When the DTC Sets
The PCM does not illuminate the malfunction indicator lamp (MIL).
The PCM commands maximum line pressure.
The PCM freezes shift adapts.
The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Failure Records.
The PCM stores DTC P1811 in PCM history.
Conditions for Clearing the DTC
A scan tool can clear the DTC.
The PCM clears the DTC from PCM history if the vehicle completes 40 consecutive warm-up cycles without a non-emission-related diagnostic fault occurring.
The PCM cancels the DTC default actions when the fault no longer exists and the ignition switch is OFF long enough in order to power down the PCM.
Diagnostic Aids
Ask the customer about possible overloading, exceeding the trailer towing limit, or towing in overdrive.
Ensure that the PCM has the latest calibration update.