Rough downshift from 2nd to 1st in auto mode

[Silver Cervy]

Got a cel today when I started my car up, so I decided to drive in auto mode to work so I wouldn't stress the engine too hard. On the way I noticed that whenever I came to a stop the car would shift very roughly from 2nd to 1st, and would make a noticeable clunk. Switched to manual for a bit and it downshifted like normal, did not notice any clunking, then switched back and the clunking returned. I've barely driven in auto mode since getting the car so I'm wondering if this is just normal for AT models?

In regards to the cel, I'm gonna have it read at Autozone after work, but would a cel pop up for transmission issues? My hunch is the cel is being caused by a header leak because I heard some rasping when I started up the car that I had never heard before (I'm still on stock header), so I don't think the code and the clunking are related. Thoughts?

[Silver Cervy]

Update: Cel was just an evap code, so definitely unrelated to this issue.

With the stop-and-go traffic on the way home I had a lot of chances to get the clunk to happen, and I'm convinced that it isn't the transmission. The clunk happens in both auto and manual mode and it is definitely coming from the right rear corner of the car. It only happens when I'm slowing down to a stop and get to 10 mph, and only if I'm applying moderate-to-heavy braking (so if I'm crawling to a stop it doesn't happen). If I had to describe the clunk, it feels like the wheel gets caught on something for a split second and I hear a small bump noise. Because of this I want to think that it's the brakes but I honestly don't know for sure.

Anything I should look for when I inspect the wheel tomorrow?

[humfrz]

You may wish to inspect the CV joints on the axles.


humfrz

[Ultramaroon]

I'm going to risk incurring @humfrz wrath and respectfully disagree.



Have you hit any potholes recently? I know, North Carolina but...

Brakes could be the culprit but I'm leaning towards a blown control or toe arm bushing. If you grab the top of the wheel and shake like hell until the whole car rocks, can you feel the clunk?

The old "kick the tires" saying comes from doing just this.

[Silver Cervy]

Will do some investigating tomorrow, but if something was loose in the suspension it would most likely cause a lot more racket than just a single clunk at 10 mph. Have not hit any potholes in my recent memory but may have gone a bit quick over speed bumps. The ones in my apartment complex are pretty brutal.

[Ultramaroon]

You might be surprised. Braking torque applies unique forces to the components.

[humfrz]

Well, Silver Cervy, I read your post too quickly and thought you said the clunk happened on acceleration also.

So, I'll go with a brake problem, either a lose pad, a lose caliper.

Then again, it could be a lose rear axle nut.

As for YOU @Ultramaroon ....... ...... the OP stated that the clunk was "definitely coming from the right rear corner of the car". Are their control or toe arm bushings in the rear of the car .....??



Keep us posted.


humfrz

[Ultramaroon]

Originally Posted by humfrz

Are their control or toe arm bushings in the rear of the car .....??



Keep us posted.

Augh...

Yes.

[humfrz]

........ hesh up @Cole ........ I had a senior moment ...... OK!


humfrz

[febrz]

http://www.ft86club.com/forums/showthread.php?t=12477

use search functions or google. I can provide you with a quick tutorial on how to use google if need be. just kidding. but here ya go dude

[Ultramaroon]

Originally Posted by febrz

http://www.ft86club.com/forums/showthread.php?t=12477

use search functions or google. I can provide you with a quick tutorial on how to use google if need be. just kidding. but here ya go dude

Ummmm...


no


And welcome!

[rjgough95]

Originally Posted by Silver Cervy

Got a cel today when I started my car up, so I decided to drive in auto mode to work so I wouldn't stress the engine too hard. On the way I noticed that whenever I came to a stop the car would shift very roughly from 2nd to 1st, and would make a noticeable clunk. Switched to manual for a bit and it downshifted like normal, did not notice any clunking, then switched back and the clunking returned. I've barely driven in auto mode since getting the car so I'm wondering if this is just normal for AT models?

In regards to the cel, I'm gonna have it read at Autozone after work, but would a cel pop up for transmission issues? My hunch is the cel is being caused by a header leak because I heard some rasping when I started up the car that I had never heard before (I'm still on stock header), so I don't think the code and the clunking are related. Thoughts?

This is being caused by your CEL. I discovered this a few years ago with my aftermarket exhaust headers. It is sort of a limp mode only in the Automatic. Pull the fuse out for your ECU and leave it out for a couple minutes and put it back. Start it up and it should be gone for a short amount of miles until the CEL returns.

So your only fix seems to be either fixing the exhaust issue or get a OFT and turn off the CEL code.

[Silver Cervy]

Originally Posted by rjgough95

This is being caused by your CEL. I discovered this a few years ago with my aftermarket exhaust headers. It is sort of a limp mode only in the Automatic. Pull the fuse out for your ECU and leave it out for a couple minutes and put it back. Start it up and it should be gone for a short amount of miles until the CEL returns.

So your only fix seems to be either fixing the exhaust issue or get a OFT and turn off the CEL code.

Yea that was probably the case. The CEL was for an evap leak which was caused by the fuel pump cap coming loose. After I got it fixed the clunk went away completely.