Humidity - Transmission issues

[procon]

I have a 93' Ford Taurus (3.0 L, Automatic Sedan). Whenever it rains overnight or if it is very humid, the first time i start the car, the whole car shudders and does not like to shift. Its like stuck in one gear. I have to wait for it to heat up (atleast 20 mins) until i can shift. If i dare to shift before it HEATS up, the engine stalls.
Has anyone had this issue or similar thing? Please advise.

[shorod]

I'd start by giving it a good tune up, specifically distributor cap, rotor, spark plugs, and spark plug wires. The symptoms you describe are pretty common for a cracked distributor cap - moisture gets into the distributor through a crack and shunts the spark to ground through the condensation rather than through the spark plug wire and plug. The car may idle, but as soon as you put a load on it, it misfires horribly bad and stalls.

If that doesn't fix the gear change issue, then you should check the condition of the transmission fluid. If the fluid is badly burnt, it could cause the pressures to be off, effecting the shifting. Or, you may have a vehicle speed sensor (VSS) that is faulty.

-Rod

[procon]

Thanks Rod. I will get all those checked.

Also someone mentioned about some "Ground Strap" not being attached could cause this kind of problem. Do you know anything about that?

[shorod]

There are multiple ground straps in the engine compartment, and probably one for the transmission, but I'm not certain. I would not expect that a loose or missing ground strap would cause the symptoms you describe.

The ground straps are there to reduce noise and ground loops, but I would not expect issues due to ground straps to only show up in humid/condensing situations. Your problem is likely due to moisture in a connection somewhere causing a sneak path for the signal.

-Rod