Not down shifting properly

I_HATE_MY_TRUCK

MEMBER
CHEVROLET S-10

I have a 1994 S10 Blazer. Two wheel drive, 4.3 Vortec V6, auto trans. 93,500 miles.
I had the trans rebuilt about 2000 miles ago. Recently it developed a rough idle problem so I took it to the dealer. The theory was that the intake (upper and lower) was plugged up with carbon. $600 dollars later both manifolds had been removed and “scraped out”. The problem persisted and I replaced the EGR valve. That took care of that. But every since the trans shifting pattern has changed, kind of down graded. Off the line if I punch it, it will shift into second gear way too soon. In drive at 30 mph it will half-heartily down shift into second, but at 35 mph it won’t.
On the freeway, in OD it will not down-shift at all. Any thoughts or ideas? I would appreciate any response. Thank you

1 Reply

BMRFIXIT

MECHANIC
19,053 POSTS

Hi there
tranny on this truck need vaccum from the engne
to shift at the write time that it should
so make sure that the vac line going to tranny ok
chek the vac line @ the tranny side
if all good and ok
on the tranny side if you pull the vacc line out you can see an adjusting screw you can try 1/2 turn at the time in connect the vav line and try it
if its improving keep at it untill you like it
if not you can try 1/2 turn out
good luck