Allison Stutter shifting up hard shifting down

[Chevman-D]

OK so here is the story.

I Just purchased my first Duramax/Allison Silverado a 2003 2500HD with 132,000 on it. Was working great then started having shifting issues and found a blown C5 Clutch backing plate. I swapped out the transmission while out put new bell housing gaskets pump seal etc in so I didn't need to go back in if the used one leaked, also put in the brand new Shift solenoids I had and Transgo shift valves with upgraded e shift valve spring along with a new PMS and of course new filters. It was shifting fine didn't do any hard pulls just part throttle. The truck is bone stock nothing done no tunes anything. So since it was shifting fine and temps looked awesome and cool I took it to work a 45-minute ride. When I got off the highway I had hard downshifts and the upshifts would stutter but I could get into 5th gear. So brought it home and parked it. I have No codes at all. Oh forgot to mention yes it also has a brand new NSBU switch also.

Any ideas what to check? Used trans shifted fine in the truck it came out of.

Thanks in advance guys and or gals

 

[coker6365]

Is the stutter shift in a certain gear, upshift, downshift, etc?

 

[Chevy1925]

you changed a whole lot of thing that that TCM has never seen before. At this point, we have no clue the health of that trans nor does the TCM and its trying to relearn everything you just changed on it.

Make sure fluid level is good and go drive the thing for a long while shifting up and down out of the gears. Then shut it off for a full min and do it again. if the bad shifts dont go away after 100 miles or so of this, you have an internal issue.

Did you use the transgo shift and trim springs? if you did, those need to go asap and put a set of Mikes springs in.

 

[Bdsankey]

you changed a whole lot of thing that that TCM has never seen before. At this point, we have no clue the health of that trans nor does the TCM and its trying to relearn everything you just changed on it.

Make sure fluid level is good and go drive the thing for a long while shifting up and down out of the gears. Then shut it off for a full min and do it again. if the bad shifts dont go away after 100 miles or so of this, you have an internal issue.

Did you use the transgo shift and trim springs? if you did, those need to go asap and put a set of Mikes springs in.

I'm trying to get access to a tech 2 my father and I share so I can put his truck into fast relearn.

 

[Chevman-D]

The Spring I installed was just the E shift spring upgrade that was slightly stiffer for the stuck E shift valves, the valves are the Steel transgo replacements. I didn't do anything to pump pressure or the trim valves. That is all stock. I was reading about Mike's Springs will save that for the rebuild on the one I took out. Trans temp was awesome nice and cool.

This is why I replaced the Transmission. https://www.youtube.com/watch?v=Z-gOpUqqh1c

The Stutter shift is through all the gears up and slamming all the gears down. I should note the OLD trans did this same shifting before the broken backing plate was found and gave me the stuck E valve code hence the spring I just installed in the used trans I put in for now. I drove it for about a half-hour to forty-five minutes part-throttle shifting all the way up and all the way down was shifting fine till I took it on a highway ride in 5th gear for about 45 minutes to work, came off the highway and started the harsh downshifts but upshift was fine, pulled in for a coffee and when I pulled out had a shift stutter was like it dropped out of gear waited and then slammed into the next gear, did this all the way the rest of the way to work. Parked it turned it off and when I went back out and it acted the same way. I am lucky enough I work with BdSankey and I am probably driving him nuts with my questions and mind thoughts being a newb to these trucks. Love the thing so stoked to get it up and running right so I can build the old transmission and have him get me a few tunes in it.

 

[2004LB7]

Debre in the cooler may have made its way into your new trans if you didn't clean or replace it

 

[Bdsankey]

Debre in the cooler may have made its way into your new trans if you didn't clean or replace it

I'm betting a relearn with help greatly. The truck has adapted to the old trans with broken parts.

 

[Mike L.]

Sounds like a trim valve sticking.

 

[Chevman-D]

Mike,

I can Drop the Valvebody this weekend and give them a once over. I didn't take them out at all in this trans. Anything I should do to clean them and the bores besides Brake clean? Being they are coated I don't want to mess up the finish on them. Just some ATF and Vasaline for reassembly? May as well do it before clearing and relearning it. I am kinda getting at home under this thing.

Thanks

 

[Chevman-D]

Ok so, nothing in the valve body. Did a fast learn and same issue. No lights on BUT I do have a P0561 code I cleared it with a Tech2 came back.

 

[JoshH]

That is a voltage code. Have you verified your alternator is charging correctly? If it is, it sounds like you have a wiring problem not getting proper voltage to the ecm, and it is probably affecting the TCM as well. I would look into the code before further diagnosis. Incorrect voltage to the trans or TCM will cause strange problems.

 

[Chevman-D]

I watched on the tech2 as I moved the harness around and connectors and it stayed at 12.5 engine not running and 14.20 to 14.30 running. Alternator is new about 3 months old. I shifted drive to reverse watching to see if engine torque changed it but it didn't. BUT after doing that a couple times when I let it in reverse and was going to see if adding torque did anything it would engage disengage engage disengage. I found something about checking pins 1 and 5 on the TCM gray connector. Had .9 to .8 ohms. Ignition switch is new about 4 months. ago. Battery grounds are 1.0 ohms harness and battery to engine. Cleared the code did fast learn again started shifting good then back to wrong like usual but now no code.

 

[Chevman-D]

So I picked up a TCM out of a 2005, reflashed it with the tech 2, went through the fast learn, drove around up down shifts probably at least 20+ times about 10 under tow haul. After first 10 or so upped to about 3/4 throttle. Temp stopped climbing at 152 and was still shifting good so far. So fingers crossed I had a bad TCM. If it acts up I will let everyone know. This week will be using it for some local runs see how it does.

 

[Chevman-D]

Update for anyone following or if you ever have the same issue. As of today, she is still shifting as she should. Tonight will be a tow test with a tandem axle trailer and around 5,000lbs on it. Yeah, I know that's nothing for these things but the first test under a moderate load anyways.

 

[Chevman-D]

Well, it looks as if I have it licked and as of now the New TCM, Reflash and relearn solved the issues. Used one of the Clone Tech2's and it worked great, Reflashing the TCM for my Truck was not as bad as I thought it would be and putting it into Fast learn was simple. Towed the trailer in Tow haul for an Hour truck was lucky if it saw 140-145 on the trans temp, she stayed nice and cool. Starting to wonder if the Bad TCM is the cause of the snapping of my C5 backing plate now. But anyways I hope this Thread helps someone in the future if they have a similar issue. Also thanks to everyone for trying to help me figure this old girl out. You're a great bunch!

 

[DAVe3283]

Thanks for the update. Glad to hear you've got it fixed!

 

[dirty_max]

I am glad you came back and updated us. I am having the same issue in my 2002 with a built trans. Seems like 2 to 3 it stutters, then 4 to 5 it stutters, then bangs into gear while downshifting. It just seems really delayed. When i come to a complete stop, the truck jumps forward after about 1 second. I have a tcm from an 01 and one from an 02 but both were from 2wd trucks. Can i use them? And can i use my v2 to flash and reset them? I tried a relearn through the cts and it seemed to help a little at first but went back to being angry at me. Ever since i bought the truck on random and rare occasion it would have a hard downshift. The other night i had my truck out and beat on it a little. It was fine and never acted up all night. Let it sit 2 days and now it's doing this.

 

[Mike L.]

History on the trans?

 

[2004LB7]

Is the ecm tuned?

 

[dirty_max]

History on the trans?

Not 100% sure. I just bought the truck this summer. Was built with a ppe kit about 50k miles ago.