Need help with automatic tranny (number two)!
 

Hoping someone can help me resolve this problem easily.

I've got a automatic transmission in my SI (SOHC VTEC) 1996 Civic hatch. The tranny works fine when the car is cold or just starting to drive (first 30 minutes or so). Once the car is fully warmed up (after 30mins-1hr) in city driving it starts getting slushy. The autotranny will shift rough and slips when taking off quickly from a light!

I've had the fluid changed and slip additive (Honda) added to try to help and it still does it.

Now before all of you start telling me the tranny is bad (valve body?) I had the transmission changed out and replaced with another lower mileage version. The 2nd transmission is doing the exact same thing! (even though it was good in the original car)

HELP! This is starting to p!zz me off as I can't beat on my lowly Civic.

Other Info:

- The car has a motor swap from D16Y7 to D16Y8.
- Two transmissions tried both have same symptoms
- install aftermarket rad (auto cooler) a couple years previous.

When you changed the tranny did you change the torque converter with it?

Thanks for the tip, I always thought the TC was buried in the tranny.

I took the car to Honda and had them do a auto tranny fluid change (changed it twice to clean out the old stuff). Looks like this may be helping but still have to drive the car long enough to super heat the fluid (ie. for a couple of hours in traffic).

NOTE TO ALL AUTO CIVIC OWNERS: Make sure you use Honda tranny fluid ONLY! No additives, no dexron crap made for Honda's. I did some more reading and the tranny's are sensitive to sticking with Honda fluid only.

I am actually having similar problems with my 1990 civic automatic, its ok when the car is cold but once it warms up the tranny starts shifting harshly through first and second gear. I suspect its the torque converter but im not sure.