Truck is a 2000 Silverado 5.3 z71. So around 4 months ago I installed an aftermarket 3200 converter, I do not recall if the converter locked up right after the install, as I made the switch to speed density around the same time. Anyways, I drove it for 4 months without lockup until one day it tried to lockup, but shuddered and went back to being unlocked. Well driving it in this state caused excessive wear on the lockup clutch, which sent clutch material through the transmission, and damaged the tranny. I went ahead and got an RPM LVL6 unit, and sent the converter back to the manufacturer so that it could be refreshed. Got the truck back together yesterday, and still no lockup!? Got with my tuner to try and manually lock the converter, still would not lock.

Does this sound like a wiring fault somewhere? A possible conflict between the speed density tune and the converter? Not sure what to do, being that it's a brand new tranny and brand new converter, there must be an underlying issue that I cannot determine. Thanks for your time!

 

Feel free to post or email your tune file and I will have a look for you on the tuning side.

 

So we spent a few hours double checking the tune, and all is good. The transmission is brand new, the converter is brand new, this whole situation just doesn't make sense.

Upon further analysis, the converter does lock up, but it is still allowing 200-300 rpms of slip during lockup.

At a stand still with what to do at this point. Converter company says it's the tranny, RPM says it's the converter, me and the tuner don't know what is causing it. Interested on any input you may have!

 

could be a bad lockup oring on the input shaft.

 

Sounds a lot like your TCC minimum pulsewidth is too low. You can't allow any drop in pressure to the lockup clutch when trying to apply the clutch. GM converter lockup clutches are designed to slip; aftermarket converters are not. Better check that calibration or you will trash the trans again.

 

So how do you decide what to make the minimum pulse width?

 

Whatever duty cycle results in apply pressure that won't let it slip. You could figure it out, but no need really...just set it to 90% or greater and you're good.

 

Rpm does a pwm eliminator on their trannys, so no issues would arise based off that. As far as the tune goes, the tcc is set to 100, as well as the DC. Almost positive it's a converter issue. Going to put the stock one back in tomorrow to verify that it works.

 

Almost a year ago since I posted this. The issue ended up being the converter, which was a single disc. Upgraded to a triple disc and I am getting full lock-up. From the information I gathered, these heavier trucks sometimes push through a single disc, and the triple disc can apply the needed pressure to lock the clutch up.