Torque Converter Problem?
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Torque Converter Problem?
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Hey guys need some help figuring this one out. The truck starts and drives normal until 4th gear. Once the truck shifts from 3rd to 4th it feels like I'm suddenly driving on washboards. The speed is about 40 MPH and the RPM is about 1200-1500. If I'm on a flat stretch and just give it slight throttle it gets worse through about 60 MPH. I have the identical symptoms if I set the cruise and accelerate using the cruise. If I accelerate a little more aggressively and keep it in 3rd I can speed through those speed ranges without a problem. But as soon as the tranny goes from 3rd to 4th, its back to feeling like I'm on a washboard road again.
Any ideas? I'm thinking torque converter but wanted to hear if anyone had other ideas. Is there any way to eliminate the TC as the culprit? Thanks!
Hey guys need some help figuring this one out. The truck starts and drives normal until 4th gear. Once the truck shifts from 3rd to 4th it feels like I'm suddenly driving on washboards. The speed is about 40 MPH and the RPM is about 1200-1500. If I'm on a flat stretch and just give it slight throttle it gets worse through about 60 MPH. I have the identical symptoms if I set the cruise and accelerate using the cruise. If I accelerate a little more aggressively and keep it in 3rd I can speed through those speed ranges without a problem. But as soon as the tranny goes from 3rd to 4th, its back to feeling like I'm on a washboard road again.
Any ideas? I'm thinking torque converter but wanted to hear if anyone had other ideas. Is there any way to eliminate the TC as the culprit? Thanks!
Lead Driver
Joined: Jun 2003
Posts: 8,298
Likes: 25
From: Damon (South East Texas)
Do you have or access to Auto Enginuity or other scan tool that can monitor shifts, TC lock up, and slippage? I have seen worn Center Support (one inside the trans), along with bad bearing, cause a vibration in OD at low speeds. Not saying this is your problem. Hard to diagnose "feels like" situations over the web. 
Lead Driver
Joined: Jun 2003
Posts: 8,298
Likes: 25
From: Damon (South East Texas)
The reason I ask is that monitoring shifts, TC lock up and PW, speed, and other parameters could aid in determining the cause of your problem. Some defects will not set codes. Armed with more information can aid in this determination. I like to be triple sure before just swapping parts.
Logistics Pro
Joined: Dec 2010
Posts: 4,738
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From: Temperance, MI
You can use the torque app to see rpm slippage. That's how I diagnosed mine.
If the converter was the problem it would happen in 3rd too most likely but be much more noticeable in 4th. When mine went out the computer would see slippage and kick the trans down to 3rd gear. Even going up a slight hill. It played a 3rd or 4th gear guessing game on itself until the road flattened back out or I was going down hill.
Never any SES light either. I took it to my trans guy and his fancy snapon couldn't see rpm slippage on it. I got out my phone and the torque app and had him hold it and look at it while I drove. By the end he handed my phone back abd said your converter is junk
If the converter was the problem it would happen in 3rd too most likely but be much more noticeable in 4th. When mine went out the computer would see slippage and kick the trans down to 3rd gear. Even going up a slight hill. It played a 3rd or 4th gear guessing game on itself until the road flattened back out or I was going down hill.
Never any SES light either. I took it to my trans guy and his fancy snapon couldn't see rpm slippage on it. I got out my phone and the torque app and had him hold it and look at it while I drove. By the end he handed my phone back abd said your converter is junk
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Thanks guys! I'll give it a once over again to make sure I didn't miss anything obvious. This thing has run like a top for the last 7 years so I've been kinda spoiled in not having to do much more than fluid changes over the years. Now I got something going on and it's like "ohhh snap" I hope it's something obvious.
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Tuned
Joined: Jan 2004
Posts: 476
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From: Hickory, North Carolina
I had a similar problem and on the way to replacing the torque converter we discovered a cracked flywheel. Replaced the flywheel and it cured the noise and vibration. Hard to say for sure if it's the same as what you are experiencing but it sounds similar to what I had going on.
David
David
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You can use the torque app to see rpm slippage. That's how I diagnosed mine.
If the converter was the problem it would happen in 3rd too most likely but be much more noticeable in 4th. When mine went out the computer would see slippage and kick the trans down to 3rd gear. Even going up a slight hill. It played a 3rd or 4th gear guessing game on itself until the road flattened back out or I was going down hill.
Never any SES light either. I took it to my trans guy and his fancy snapon couldn't see rpm slippage on it. I got out my phone and the torque app and had him hold it and look at it while I drove. By the end he handed my phone back abd said your converter is junk
If the converter was the problem it would happen in 3rd too most likely but be much more noticeable in 4th. When mine went out the computer would see slippage and kick the trans down to 3rd gear. Even going up a slight hill. It played a 3rd or 4th gear guessing game on itself until the road flattened back out or I was going down hill.
Never any SES light either. I took it to my trans guy and his fancy snapon couldn't see rpm slippage on it. I got out my phone and the torque app and had him hold it and look at it while I drove. By the end he handed my phone back abd said your converter is junk
Then he didn't know how to read the data or operate the scanner (most people don't) because the fancy Snap-on scanner will read TCC slip rpm. Even the old red brick MT-2500 will read the PID for TCC slip.
As for the OP's question....this could be TCC shudder and doesn't always show as a slip when viewing the PID for TCC slip or create a trouble code. If you can read the PID for TCC slip then the RPM should be as close to 0 when the PWM has commanded 100% (converter locks up.) If you barely feather the throttle without the TCC disengaging and see it go more than 50 RPM, then the TCC is slipping and the trans needs to come out.
This symptom is always way more noticeable once the trans is in 4th than when the TCC is locked in 3rd as RPM is much lower which means trans pump output is a little lower and there is much more load in this state (4th gear).
However, I have seen engine runnability issues cause this symptom as well IE injectors, misfiring, etc. so it doesn't always mean the converter has taken a dump.
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Jun 21, 2007 10:46 AM