Hard 3-2 downshift turns into blown tranny?

[Aphix]

A little background, my car has occasionally downshifted itself from 3-2 in the past as I am slowing down using the brakes. It wasn't a hard shift and I took it as normal behavior.

Well today I'm doing about 35 down the road when my tranny all of a sudden does a full line pressure 3-2 downshift and scares the hell out of me. After the light I begin to accelerate and realize the transmission isn't working right at all. I couldn't even tell what gear it was in, it was very loose. On top of this, the car began to idle around 2k rpms and had a sputter almost like I had a boost leak?

I was almost home so I limped it back, pulled the CEL's but had nothing. I sat there and shifted it in and out of gears a little and found that the reverse to drive shift was very rough and I could hear a metal-on-metal popping as I did it, however this could be from shifting with the high idle, Im not sure.

I hadn't been running the car particularly hard today. I changed the fluid and filter less than 7k miles ago, fluid level was fine also. Any insight on this would be great.

The transmission downshifting itself very hard at a coast and then acting erratically has to be indicative of something.

 

[twicks69]

Yeah, it sounds like your auto needs a rebuild. You could have damaged the reverse kickdown band, the reverse sun shell could be galled up, you could have shitboxed some frictions/steels, maybe a solenoid issue, a clogged/damaged oil passageway in the valvebody, it could be a bunch of things. Either way, it sounds like a full teardown is the smartest solution to find the problem.

 

[Aphix]

Ok thanks. Now I have a direction to go with this thing.

Also, the engine is acting like it takes longer for it to idle down as well. When I rev it up in park it will sit at a higher rpm for awhile until falling back down.

 

[twicks69]

Ok thanks. Now I have a direction to go with this thing.

Also, the engine is acting like it takes longer for it to idle down as well. When I rev it up in park it will sit at a higher rpm for awhile until falling back down.

It could or could not be related to your transmission issues. I would focus on one thing at a time, then troubleshoot each one and minimize variables.

 

[Aphix]

The engine was running great up until that hard downshift so I would imagine its related to the transmission. I just didnt know if that might be a symptom. I just trailered her to my shop so I'll drop the transmission and take a look hopefully this weekend.

Also a little more info, the transmission is able to shift in first through third gear, I never tried fourth. It isn't particularly smooth though. But it will go into gears fairly quickly. I guess my biggest lead is the fact that it wanted to downshift itself from 3-2 and that when it really went was after the worst 3-2 downshift I'd ever felt. Possibly a kickdown servo/band/drum issue?

Also something I entirely forgot to mention, when the car has sat all night and I goto drive it, I will throw it into gear and have to let it sit for about 30 seconds before it will want to engage. I assumed this meant there was a bad seal and the fluid was draining over night.

 

[Aphix]

Finally got around to looking at the car in this crazy weather we're getting. I was talking to my buddy about it and we both agreed that there must be some sort of electrical short or ground issue. So I did a quick log and was getting very erratic readings from the TPS, jumping from 40 to 90% at idle while I'd had it properly adjusted at 13.333% not very long ago. The car was also advancing timing to around 25 degrees at idle and getting high knock counts and then retarding it in a sort of cycle. To me this all points towards a short circuit of some kind.

I was also driving it and was able to shift through all gears and could only get the transmission in limp mode by doing a 4-3 downshift at cruising speed. Maybe a kickdown servo issue? I'm not too familiar with automatics though.