audisport12

The car is a 2000 4.2 w/ 103k miles.

Randomly now for the past while when I drive the car cold, the first shift clunks HARD followed by the gear selections on the display screen lighting up in all red. To make it shift correctly after that, I have to turn the car off to reboot it. Then it works fine.

Today it happened twice back to back in the middle of campus with all sorts of traffic behind me. After I turned the car off, then on twice, I got a CEL. I had Autozone scan the codes and it brought up:

P0730
Definition:
Gear incorrect ratio

Explination:
Open or short circuit condition

Probable causes:
1. poor electrical connection
2. low transmission fluid level
3. failed transmission solenoid

Another weird thing that I'm concered about is when taking off from a stop and steadily driving slow in 2nd gear, when a LITTLE bit of throttle is given, it jumps down to 1st then back up to 2nd pretty quickly. Also when driving on the highway cruising around 55-60mph, if I punch the throttle, it tries to search for a gear and will sometimes slam into 2nd when not needed and then kick back up to 3rd.

Now I know these cars are known for having tranny problems, But I am not sure if this is something that can be dealt with before anything gets worse.


Sorry for the long post.
Any idears?

MP4.2+6.0

Ideas. If you search for posts you will find a bunch, including extensive ones from me. I have a 2000 4.2 since new.

1. Check tranny fluid of course.

2. Change tranny fluid and filter. Lots of posts on this. Likely won't cure, but may help.

3. Replace MAF (mass airflow sensor). May seem odd to replace the key engine fuel flow component, but the MAF is tightly coupled with all of the electronic throttle, the ECU, and the tranny computer (TCU/TCM). ECS tuning sells rebuilt ones that are essentially new. Can also be cleaned (maybe...) with rubbing alcohol or electronics parts cleaner. Again, there are prior posts on this.

4. Get tranny valve body rebuilt. Can be done with tranny entirely in the car just by dropping the pan. I did a long post on this some years back. Really tightened up my shifting. Cost some $$ though, so you may just want to try a fluid change, the MAF tweaking and the item I mention next.

5. Check output speed sensor wiring. Of all things, this obscure thing was my definitive problem. Needle in a haystack to find, but I ohmmeter checked it and it was discontinuous. I spliced around it from the sensor to the tranny TCU and problem 100% solved ever since. Look for a prior post of mine detailing this too.

MP4.2+6.0

<ul><li><a href="https://forums.audiworld.com/a6/msgs/619706.phtml">output speed sensor problem</a></li></ul>

Stampy

I found an old post on here that talked about the throttle body being filled with gunk. The theory was that the plates inside the TB couldn't close all the way/react quickly enough covered in gunk. So I took off all the intake piping and cleaned out the throttle body as best I could. Man, I really pulled a bunch of crap out of there. In my case it helped tons. The problem was pretty much gone and hasn't returned since. I'll search and see if I can find that post.

JAGMAJ

Those can sometimes cause the cars to shift hard and to go into limp mode. I'm not sure whether that would throw your code, though.

MP4.2+6.0

I tried for hours and just couldn't get it out of the 4.2 when I suspected it. It seems to really need the tranny to be dropped, which then begs a whole rebuild question

MP4.2+6.0

In turn this ties into what I mentioned about the very tightly coupled ECU and MAF--the throttle body is directly downstream of what the MAF is reading and of course links right to the electronic gas pedal. If you pull the MAF out to replace or clean it, definitely do the throttle body cleaning too. It's easy to get at by just pulling off the 90 degree big rubber boot.

WOWDee

next question would be why? where is the leak? pan or torque converter / pump seal ...... to check the fluid level u will need a bently manual and vag com ... follow the instructions ...... if fluid change/level does not solve u will probably have to pull it 4 a rebuild ...... diy pull &amp; send in 4 rebuild was $2500 ...... dealer quoted $6k for entire job