i just got done installing a tci 3000 stall and transgo hd2 shift kit in my 2003 gmc 4l60 and i got the pcm tuned for the changes but when im driving it at around 40 mph when i accelerate after it shifts and downshits at 40 i get a vibartion noise and it only happens if i gradually accelerte if i go easy it doesnt make the noise and if i go hard it dosent make the noise could you give me a idea of what it could be thanks guys

 

Try and isolate it. Put it in park and and rev it slowly. If you feel it then its in the engine, TC. If it is unbolt the TC and spin it one bolt location and bolt it back up and try it again.

If you don't get the vibration in park it might be in the tranny or drivetrain.

 

yea its not in the tc cuz it only vibrates after the shift its usually, i think the 2-3rd shift and its only for a little bit and once its past that it runs fine and dosnt make the noise at all

 

sounds like the noise and vibration is coming from the tc. your probably experiencing converter shudder, it occures when the tcc goes in to lock up and unlocks when a load is put on it. i had this problem with mine. the lockup clutch went out after 5k mi. now i have the upgraded one only b/c they refunded me. next time i'm going with a fuddle or tb stall.

 

I thought about the TCC lockup but at 40MPH and acceleration?

 

during slight acceleration after 40 or so the converter would stay locked and create shudder, noise, vibration. or so that was my case.

 

so iff it is the tcc how the hell do i fix that or what should i replace ?

 

there's an additive you can add to help it or fix it. pretty much the tci verters are knowned for that in these trucks, judging by everyone else's experience including myself.

 

ok ill try that thanks alot guy uve been a big help

 

Remove Pulse Width Modulation for the Torque Converter Clutch circuit with programming or valvebody modification. The valvebody mod is easy, but you do have to drop the pan and valvebody to do it. If you're interested in doing it I'll post how.