odd c70 trans problem

Gerry_cal · Post by **Gerry_cal** » 04 Oct 2010, 11:20

I have an '02 C70 HPT with the (i think) AW55-50 le trans 75000 miles. The fuild looks a little dark and I plan on doing the drain, fill, drain, fill act on it.

Now my problem. The car upshifts fine, smooth at light throttle, firm at heavy (sometimes with a 1-2 chirp of the tires). The problem is some times (not often enough to reproduce on demand) when on cruise control or light throttle when getting to a uphill where a downshift is required (like at low RPM <2000) when it downshifts it seems to go out of gear, to a neutrl type state, the RPM's climb way high (often up to 4000 or so) then it will bang hard into gear. It happens in several gears, at different speeds. This bang can be hard enough to chirp the tires. I have had to car to a trans shop and they could not reproduce anything or find that it had thrown any codes.

All I can think of is either a valve body problem, low pressure from the pump (is this checked by a computer when hooked up? the shop did this while I drove to try to reproduce- but could not) or something in the computer. Anyone heard of this before? any clues?

Thanks for any answers.
Gerry

FCPEURO · Post by **FCPEURO** » 04 Oct 2010, 19:42

I am thinking valve body also but flushing the fluid first would not be a bad idea. It is a cheap thing to do and could fix everything. Could also be some dirty clogged up in the fluid tracks. The tracks are small so if there is a clog, it would almost stop fluid flow.

jda2000 · Post by **jda2000** » 04 Oct 2010, 19:51

try seafoam transtune just before you replace the fluid, to clean all those internal tranny components

Post by **JRL** » 04 Oct 2010, 20:31

jda2000 wrote:try seafoam transtune just before you replace the fluid, to clean all those internal tranny components

I would not do that.
You need to do the usual, clean fluid, (flush or drain and fill twice) software upgrades (if any)
RESET THE ADAPTIONS, DO THE DRIVE CYCLE

This is the first sign of a bad early build AW 55.
if none of the above work, unfortunately a new tranny will be in order but sometimes what I said can make it 90% better

Gerry_cal · Post by **Gerry_cal** » 07 Oct 2010, 20:03

I want to thank everyone for the answers. I will do the drain/fill bit a couple times and give it a shot. For resetting the adaptions, can most better trans shops do this or am I stuck going to the dealer? Also can you give me a link to the drive cycle? I know with many newer F/I systems the relearn can take a lot of things to fill the map in.