Trouble shooting need help

[alexanderfrazier]

Ok first things first. I did as much research possible and still haven't found an answer.
I have a 1990 Nissan 300zx with auto transmission, everything stock.
The problem Im having is that when the car gets wet (rain, washing it), transmission will only shift at over 4500 rpms. Now onces it dries a couple days its back to normal, it shifts fine.

Ok, what I have done so far: I did a auto trans.diagnosis and the third light flashes longer which is the throttle position sensor.

After everything dries it no longer shows a problem with tps. So something is getting wet perhaps and throwing the tps off which obviously affects my shifting.

One last detail. There is a missing vent cover where the wipers are, the one that doesnt allow water to get in the engine bay righr near the battery is. So I have recently noticed that battery gets wet along with anything else in that space.g
Any ideas would be much appreciated!

[Ziggy1621]

On that side of the motor is where the wiring harness goes to the transmission. I would inspect the wiring harness to make sure nothing is exposed and/or possibly rubbing on another part. Water is a conductor of electricity, so it is possible the water is causing the cable to ground out. Just a guess

[Ace2cool]

To add the that, there's also a relay block on that side right next to the battery. Not sure if there are any transmission related things in there, but it couldn't hurt to have a look.

[alexanderfrazier]

Thanks for the suggestions. Things are getting dry again and its running back to normal. I want to isolate the problem, does anyone know where I can buy that piece thats missing? The plastic vent piece right where the battery is.

[ThisIsSparTTa]

Thanks for the suggestions. Things are getting dry again and its running back to normal. I want to isolate the problem, does anyone know where I can buy that piece thats missing? The plastic vent piece right where the battery is.

That's called a cowl. They aren't really made anymore, they're all brittle and broken, and people are charging an arm and a leg for them. Here's both sides http://www.conceptzperformance.com/Cart ... 164.64.142 and just the passenger side http://www.conceptzperformance.com/Cart ... 164.64.142. Flame away, but I've seen some cheap plastic ones on fleabay for $60-70 that are unpainted that I've considered getting. $130 for a piece of plastic burns a bit...

[t.mcginley.jr]

^ to add to that

http://www.ionicdynamics.com/300zxnew13.html

$59.99 + shipping for a new fiberglass one

[Ziggy1621]

Only thing is, I've heard the fitment on the ion dynamics one is not good.