What causes inconsistant tranny pressure?

[AznGA]

I am having some 1-2 shift problems with my 02 Grand AM GT. It only happens during WOT. Sometimes the shift is very firm, meaning it slams into 2nd. And sometimes the shift is very loose and the car hunts for the 2nd gear and the RPM just moves up and down once, and finally shifts into 2. Any ideas?

[sil]

best bet to check the actual pressure

what tranny do you have ? 4t60-e?

could be alot of things, best to take it out on a long road then do a road test

make sure car/tranny is warm
from a stop position with lever in d or od if equiped accelerate moderatley and record the shift points from 1-2 2-3 3-4(od) on paper

then test your part throttle downshift at about 45mpg in highest gear (od if equiped) quickly press the accelerator halfway and hold it, the tranny should downshift 1 gear

test full throttle downshift, repeat, but quickly press the accelerator full tot he floor, the tranny should downshift 1 or 2 gears

test for coasting downshift by coasting from highest gear to a complete stop, write down the downshift speeds from 4-3(od) to 3-2 to 2-1

test manual lows put lever into first and accelerate, the tranny should not shift into second and when deaccelerating should provide engine braking

same as 2nd but tranny should shift from 1st into second and should provide engine braking on deaccelerating

check manual 3-2 downshift quality by moving the lever from drive into manual second at a moderate speed, not too fast you dont want to over rev the motor but you do want it to be a noticble downshift
check for engine braking, hesitation? slippy? or firm?

stop car place lever into neutral and listen for noise or vibrations

place into reverse and and check operation at idle and part throttle

[AznGA]

How do you check the pressure?
I have 4T45E.

[sil]

hmm im not familliar with the 4t45-e
but there should be what looks like a bolt somewhere ontop of the tranny near the side pan.. take that out put a hydraulic pressure gauge into it and then you test pressure at idle in gear and also with brake on foot and in gear and at a specific rpm