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issue with transmission downshifting

91gpse

91gpse

New member
ok so i just got my grand prix back on the road.... its been sitting for a year and a half.... its got a really hard downshift... shifts fine just downshifting bangs real hard. i think it might be the valve body or soleniod but idk any ideas? its a 91 with a 4t60 trans
 


if it wasnt doing this before it sat up for a year and a half... i would think somethin is probably gunked up in valve body... try a can of seafoam trans tune. follow directions on can.
 
gtpinsc said:
if it wasnt doing this before it sat up for a year and a half... i would think somethin is probably gunked up in valve body... try a can of seafoam trans tune. follow directions on can.
Click to expand...

thats what i was thinking too im going to the parts store anyways today so ill pick up a can.... i also think it might be a clogged trans filter and no it wasnt doing that before it sat. trans itself only has about 1500 miles on it since it was rebuilt.
 
u can "TRY" resetting the PCM. not sure if it will help. but worth a shot.. disconnect battery for an hour or so... reconnect and see if it still does it. if its got 1500 miles on rebuild id doubt its the filter. but seafoam trans tune is good stuff... has cleared up issues for me before.
 
gtpinsc said:
u can "TRY" resetting the PCM. not sure if it will help. but worth a shot.. disconnect battery for an hour or so... reconnect and see if it still does it. if its got 1500 miles on rebuild id doubt its the filter. but seafoam trans tune is good stuff... has cleared up issues for me before.
Click to expand...

the shop reset the pcm already when they put the new motor in. i bought lucas oil high milage transmission treatment. i put some in and its already 10 times better so my guess is it was just full of gunk. shifts alot smoother and downshifts a little better... a buddy of mine that works there said itll take about 100 miles before the problem will be gone completely so i guess its just wait and see.
 
update on trans works like a brand new trans since i put the lucas trans treatment in it. didnt even need much have about 2/3rds of the bottle left...
 


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