I had a Trailblazer torque converter installed in my '03 5.3 GMC and used Redline ATF. Since the install (1) torque converter won't lock up until 3-4 miles, (2) if lockup occurs before 55 mph rpm will drop about 500 and then after about 2-3 seconds go up about 100 rpm. This appears to be a partial unlocking of the converter (PWM), and (3) if steady throttle is held at any speed between about 45 to 55 mph the rpms begin to cycle on about 2 second intervals. Slightest uphills will stop cycling at the 100 rpm rise and slight down hills will stop cycling at complete lock up.

I am looking for some trouble shooting ideas but would prefer to eliminate the PWM action. Complete 100% lockup when lockup is called for would be ideal.

Thanks

 

Any of the Trans-Go kits have this PWM eliminator valve, & this should fix this problem.

 

I have a Trans-Go kit already. I was going to sort the problem out before installing and complicating the matter. I guess I should have read the instructions before asking questions. Thanks. (Now please excuse me while I slink off to my chair and read instructions.)

 

O.K. I've read through the instructions. I can't find a reference to PWM. Since everything between the torque converter and the output shaft is MAGIC I wouldn't recognize the parts or a different name. The closest thing I can find is their reference to "Upgraded Isolator & Converter Valve" AKA "ISO-CONV Valve". Could this be it?

 

Yes, thats the valve. If you look at the side of the box that has the label, you'll notice it says "PWM Upgrade". Thats the ISO-CONV valve you saw in the instructions.

 

My o2 Z-71 was doing the same thing after the tb converter. There is a table you can tune to get rid of this. I have a westers tune and they fixed it right up. The table is called something to the effect of TCC pwm duty cycle. You can have it set up to 98-100% and it will take care of your problems.

 

oops double post: