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Shudder in Auto trans

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While cruising at 55-60 MPH if I let off the pedal slightly-not all the way- and then depress the pedal normally to speed up, the truck shudders for a second and then all is fine. Is bad enough the passengers can notice it. Actually shakes the truck fairly good.

If you let off the pedal fully and then depress it this never happens. I need to be a straight level road and can duplicate the problem.

Engine RPM's do not drop of fluctuate. Does not seem like the torque converter is unlocking and locking, but possible.

Took it to the dealership and they could not duplicate it. They updated the trans controller and the problem is still present. I'm sure I will need to drive the truck for them to make it happen.

Curious if anyone else has experienced this or knows what it might be?
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Ive had a similar problem, some guys on here told me it might be the flash that my truck is running, they say that some of the newer updated flashes address this problem
 

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I get a similar hesitation - when my truck is cold and I have the engine break on. I let off the pedal and the truck feels like it is stalling for a split second. Really makes the truck shake.

When it is warm, no problems.

RiverRunner
 

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Discussion Starter · #5 ·
This is when warm running at 35-40 MPH and 55-65 MPH without the EB on. If the EB is turned on it gets way worse.

With just a slight lift off the accelerator and then back on it shudders enough to make the truck jerk.

No drop in RPM seen, no CEL or warnings at all.

I thought about driveline wind up but this never happens if you lift off the accel completely. You need to be in between accelerating and coasting but not fully lifted.
 

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My truck also does it when cold at about 60 mph and then stops after it warms up. I don`t know if it is anything to do with cold lubricants but I am inclined to think that might be part of the problem.
 

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Discussion Starter · #7 ·
I would be OK with this is it was only when cold but this happens all the time whether cold or up to full operating temperature. I can make it happen at will.

I am going to take it to another dealer after the weekend-and test drive it with them so I can show them what happens. I get tired of the "could not duplicate the problem" BS from the dealers.
 

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Discussion Starter · #9 ·
I am not sure on what the dealer installed as they did not put any stickers/labels for what is installed. I am assuming it is the latest flash for the ECM and transmission controller as I got the truck back this week.

Truck is completely stock with no performance tuner.
 

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when I was working for a chrysler dodge dealership here in maine some vehicals would go into a partial torque converter shudder at that speed and it kind of makes sense with what you are describing because when you take your foot off the gas pedal it disengauges torque converter until a higher speed is seen by ecm , less load on vehical to lock converter I may be way off track but it possible, and by the way the dealer that is telling you that they cant duplicate the problem ,that is one of the oldest lines in a flat rate shop if they dont want to spend time looking for your complaint I see it to many times thats why I went independent i wish you good luck with that dealer
 

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A lot of trucks do this - there are tons of threads on here about it. Nobody can nail down what it is. But its mostly prevalent on trucks with power adders, when the engine is lugging at or below 1200 rpm's. It'll shake like you are going over washboard.

Mine did it once and never did it again. But I also make a conscious point to not lug the motor.
 

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thats good info to know, Im thinking of getting a different converter but only choices that I have found is ats and a company out of canada ,nacp but both are pricey. do you have any any info on converters?
 

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It'll shake like you are going over washboard.
That's the best way I've heard to describe what it does.:thumbsup:

I have found that by shifting it manually and letting the R's get up a little higher before shifting then it doesn't do it. I find it kind of ridiculous that these things are in 6th gear at 40-45mph in auto.
 

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:confused013:the other thing that happens when it gets low on rpms is pump presure in trans drops off and it could be a combined reaction to converter/pump pressure making it shudder it would be nice to hear frm someone who has already done a upgrade to see what its like now
 

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I had the latest flash in my 3500 2008 mega 6auto 3.73 done about 30 days ago.
It did it more before the flash and now is lots better but it still does it just slightly.
I dont think its any thing to do with cold or warm mine did it more when warm. And speed nothing to do with it I had it happen at walmart parking lot just above idle the motor almost stalled and the tach never moved.
I dont think its in the trans but with the throttle and the motor losing injecton for a split second.
I think its better nowI have to work at it to make it happen.

Brian
North Idaho
or Cambodia
 

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Discussion Starter · #18 ·
Drove the truck 700 miles over the last several days after I got it back from the dealer. It is way worse now with the current flash.

It does at different speeds and different RPM. Even at 75 MPH on the freeway. It does seem like it is in the torque converter.

Engine RPM does not change when this occurs and will happen at 1200 RPM through 2000 RPM depending on the speed. Happens mostly in 6th gear but will happen at slower speeds in 3rd and 4th. I also think this is the same stumble or bog that happens occasionally at part throttle from a stop. It feels like the engine bogs but the RPM never fluctuates. Truck hesitates and then goes fine.
 

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I spoke to suncoast and ats today they both say the same thing about converters and transmission, the converters are not able to handle the additional power of any tuner that makes good power(over 100) and hp gain that we all hear about is nothing compaired to the monster torque these 6.7s make at low rpms and low rpms = low line/pump pressure there is a controler that ats is working on that will adjuwst pressure , lock up and down shift, expected to be ready for 8/09 but we all know how time tables can change as far as reliablty on 68rfe suncoast said there a weak trasmission ats said there a mid grade transmission ,guess it all depends on what the applcation is but a converter will cure shudder were getting when lock up accures durring low rpms its the same problem that the 48s had just at a lower rpm with more ratios to chose from and more torque
 

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I'm getting the sputter also. I thought it may the turbo since the sound comes from the front. But now after reading this thread im thinking i'm the same as everyone else.
I get the shutter after having a light load on the engine in the winding hills and as soon as i get on somewhat level ground i sometimes get the shutter.
 
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