Built trans issue?

[joelykool]

Hey all,

Got a built trans with the gmax kit with a sun coast 1056 converter with maybe 7,000 miles on it. For a while now its been giving me an issue. It has no burnt fluid, the magnet is clean etc...But after the truck is warmed up and up to operating temp (only happens when warm)...I then shut the truck off and let it sit something like an hour or so. Start it up, say let it shift into 2nd gear in a parking lot, then slowly come to a stop. Right at 1-2 mph as I come to a stop it lurches the truck forward like its in the torque converter or something. Any idea what could be causing this. No check engine lights or anything of that nature. Wasn't sure where to begin with this. Is there an internal leak causing pressure to build somehow...any help would be appreciated!

 

[joelykool]

The truck, after it lurches forward after only have shifted out of 1st gear and coming to a stop for the first time, will not do it again until it has sat for an hour or so. So it will not lurch forward if I keep it in first gear to a stop. But as soon as it shifts out of first and coming to a stop is when it will act up. Just trying to clarify!

 

[2004LB7]

Have you talked to your builder?

 

[joelykool]

I did and he wasn't sure where to start other than to tear it down and see what we see. I was just hoping someone else may have had something similar. Its definitely in the torque converter I believe as the lurching forward is not a shift/bang of any sort. Its like a fluid motion. Its enough of a push forward that I have to be careful there isn't a car too close!

 

[oscyjack]

Before you tear into the trans, it could be something as simple as your slip yoke hanging up. Pull it, clean it, grease it and then see. Worst case you wasted 15 mins

 

[Mike L.]

Hook up a Tech2 and see what the turbine sensor is doing when it come to a stop. You may have a problem with the converter flow valve or a sprag going bad in the converter. If it was a converter clutch problem, I would think it would try and kill the engine.

 

[Hambone]

Not to hyjak or anything but can efilive monitor turbine speed?
I can't seem to find the pid for it
Trying to check for TC slip

 

[IOWA LLY]

Yes it can. I can't remember what the piddocks called, but I know Efi can log all 3 speed sensors associated with the Allison. Input, output, and turbine. It might be labeled as intermediate. I can't remember


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[WVRigrat05]

Both of mine has always done that randomly, I always thought it was fueling.

 

[WolfLMM]

Are you sure you aren't experiencing the infamous 2-N-1 downshift. It feels kinda like someone lightly rear ended you.

 

[joelykool]

I guess ill first try to log with efi live...and then move on to the tech 2. It really doesnt feel like a shift at all...very fluid pulpulsion like. Its hard to describe. Thx for the input everyone. Ill post whati find out.