Chevy and GMC Duramax Diesel Forum banner

1800-2100rpm surge when converter unlocked

123 views 9 replies 4 participants last post by  093500  
#1 ·
On a long road trip with my truck camper on my 09 3500 with 185k on it My truck has developed a weird pulse/surge when pulling easy hills i was positive it was the FPR. I had very similar issues about 70k miles ago that new FPR solved. Not so lucky this time. Spent 2 days digging into engine and replaced that... no dice.

Further testing it's only happening in normal mode when converter is un locked or in tow haul mode just in 2nd gear before it locks up. If I give it more or less throttle it will stop. If the hill was long enough and i hold it steady around 1900rpm it'll do it forever.
Can see torque converter slip bouncing while it's doing it. 100-300rpm. Truck runs and shifts like new once it's locked up. No slip even giving her the beans with my camper loaded. Worried I might be starting to loose my converter. Rather fix it before it sends shrapnel thru my trans. Have 2000 miles to drive to get home back out west. Currently in east central Iowa (Cedar Rapids area) if anyone can recommend a good trans shop to check this out! All ears!!! Appreciate the help. I want to go home! But don't want to get stranded in no middle of no where or cause more damage!
 
#3 ·
Unfortunately no... not yet anyways. Have edge monitor hooked up so that's what I'm watching data with. It's a tough one to diagnose as when rpms are bouncing so are most readings.

Might just have to send it and hope for best until issue gets more obvious. Hoping someone's had this problem or shop can read some data i can't like line pressure etc and come up with a plan.
 
#7 ·
I'm so confused do people just post in other random people's threads here? You guys need to go play somewhere else lol. Let's get back to my issue... ya know the one I MADE this post about my transmission on the transmission forum! Lolol

I dropped pan today totally spotless barely any clutch material on magnet. This is a weird one.
 
#8 ·
How many miles on your current factory located fuel filter? Could try changing that and see if that helps. My 07 lbz developed a weird surge/hesitation when getting on it around mid rpms. Only did it on tune 4 and 5. Changed filter and problem went away. My filter had about 11k on it. Just a thought.
 
#9 ·
Filter was the first thing I swapped. Had VERY similar issues about 70k ago that new fuel pressure regulator solved 100%. Spent 2 days kneeling on my radiator replacing that and same issue persists.
It's going to a shop tomorrow to get data logged while we drive it and hopefully narrow this down. Don't think it's transmission after messing with this for 2 weeks now. Just doing it with converter unlocked only had me leaning that way. But that would also let engine surge easier then when it's locked up.