1991 Dodge Shadow 4 cyl Front Wheel Drive Automatic 150000 miles
Transmission wont shift down to first gear when at a complete stop. I can shift it down into first gear or when I drop it in neutral it will drop to first gear. But if I stay in drive it will shift only down to second when I pull up to a stop light. Now if I accelerate hard of the line it will kick down from second to first then back to second and so forth like its suppost to. Only seems to be the first gear.
The governor valve is sticking, possibly due to varnish buildup in its bore. As the car speeds up, centrifugal force causes the spinning valve to move against spring pressure. As you slow down, the valve moves back due to the spring. That valve, along with the throttle position, determines shift points.
When the governor valve sticks, the transmission thinks the car is still moving fast enough to warrant staying in second gear.
There are cleaning chemicals that may help dissolve the varnish. Some cleaners must be removed by flushing and replacing the transmission fluid. There are other additives that can stay in the fluid. Ask the folks at your local parts store what they recommend for your symptom.