My Blazer wont downshift when I apply throttle at 35 + miles an hour. Not throwing any codes. New plugs new wires new distributor new transmission filter new shift solenoid. Don't know where to look please help

 

This is a 1992? If so you won’t get transmission codes as it is a hydraulic unit. Only solenoid in that will be a lock up solenoid. You need to check TV cable adjustment or a hanging governor.

 

Would you mind telling me how to check that.
I have changed the knock sensor, shift solenoid, and the trans filter.
again, I appreciate your input/advice

 

Here are some videos that may help.
https://youtu.be/xofSh2q-1M4Q

 

 

Still no improvement... Starting to think it might be the engine after all. But she runs fine in park only has the problem when I'm driving. Engine bogs and misfires,also won't shift. No codes. New governer, "tcc" solenoid, knock sensor, distributor,and tranny fluid. HELP.

 

Only 100,000 miles

 

Downshifting in 92's should be governed by two instances.

The first one being vacuum.
The second one being kick-down switching.

Not sure how it was built in the 92. AFAIK it could be a T700-R4 or a 4L60. Don't think the 92 already was a 4L60E. I think those came 93 or even only 94.

Now the question is:
Does it "not" downshift at all or does it only downshift when you hit the kick-down?

 

it will downshift if I let off of the throttle. But only while the engine is still cool. The hotter the engine gets the less likely it is to downshift at all. When I press the throttle all the way down the engine has no power transmission won't downshift and occasionally backfires

 

Interesting. IMHO it's also pointing to some other source of the troubles.

Vacuum leak maybe?