My saga seems to continue... (964 is new to me and we have limited history)

I've had the car in the shop for several weeks now. It was behaving very strangely, going into limp mode, shifting into 4th gear and very sluggish (although I have never driven a properly tuned 964 before).

Mechanic did a complete tune-up and valve adjustment (it has 53k miles). New rotors, caps, wires, plugs. It was immediately improved but transmission was still forcing 4th gear, then the car basically died and would no longer start. ECU was identified as the issue and was sent out for refurb (ECUdoctor). Upon replacement it fires up and runs strong. I still have not driven or seen the car as I am remote from the shop.

However, the report from test driving is the tiptronic will work but after a short time in either 2nd or 3rd will go to 4th on its own. Shifting back to D then to manual will allow shifting again. No faults are shown.

This does not seem like "normal" behavior I would expect. Can any of you tiptronic drivers comment on how yours operates normally. Does it ever shift on its own in manual mode?

Thanks,

 

It should not shift on its own in manual mode the way you are describing. The tiptronic will shift to 2nd when you come to a stop though. I am surprised that the tiptronic control unit does not throw any error codes.
This could be a hydraulic issue. First thing I would check is transmission fluid levels. You need to check at operating temp 80c on a level surface. Also might want to change fluid and filter. Once you have done that it can get expensive very fast. However, the tiptronic is know to be pretty reliable when maintained properly.

Good luck.

 

Thanks. I’ve been doing some research and find no explanation as normal. So... Mechanic will drive around some with the diagnostic tool plugged in. Otherwise I may live with it for a short while. There has to be a code or some other hint waiting to be uncovered.

 

Mine had a bit of a incident a couple weekends ago...

Was driving around and from a stop, shifting to second it was like it hit neutral and wasn't accelerating. Put it in D and it was going again. Couple miles further and all the lights on the gauges flashed on, car lost power and I pulled over. Turned off the key and put it in park. Car wouldn't restart, as if it was in gear. Worked the shifter up and down several times and kept trying to start the car--starter was engagi\ng, but not starting.
Turned the key off, gave it it a few min. and it restarted and was able to drive away normal.
Fairly fresh trans oil change...but it was unusual for sure.

Love the TIP, but gave me a bit of pause. I am guessing it's some sort of sensor in the cabin end of things? If it happens again, I'll be taking it in.

 

Start to change gearbox oil and filter (!) first. In my 20 years of Tiptronic experience this is the first thing to do.
Specially if you are not sure how long the oil is in.

dick964

 

Definitely do this first. The g/box takes 9.5 liters, although you will probably only get 6.5 out.
Normally the Tip is super reliable and should just go into limp home mode (3rd gear). So maybe there is an intermittent/bad electronic connection.
Next is to check and clean the electrical connections. One is in the engine bay just under the ISV.
There are two more on the left of the g/box under the car, one is pretty obvious and the other is tucked way up against the g/box case beside the ATF cooling lines.
Lastly, check the adjustment on the gear lever to g/box cable.

Sorry i do not have any photos to post...........it would have made it easier to explain.

Worst case scenario, buy another g/box. Plenty of Tips around as many convert their cars to manual.

 

OK, guys.. this is clearly valuable advice. I was actually planning this as one of my first tasks. Bought the fluid, filter, gasket, and had the lift available. But there were so many issues with the ignition I had a shop take this on first. They've done all that and have the engine running well and major leaks solved. So I'll pick up the car and get on this. Hardest part I understand is getting the fluid to the right temperature to verify proper fluid fill.

Oh yeah.. they say if driving in fully automatic mode it operates flawlessly. I'm looking forward to driving this car!

Thanks again!

 

I have most the parts for cheap. 50k miles 1993

 

If it's good in auto mode...........but not manual.........maybe check the micro-switches under the selector cover. Three micro-switches for manual mode. One to switch to manual one each for changing up or down a gear.

 

Mine had a lot of dust / dirt / crud on them. They just needed a bit of cleaning. Agree, this sounds like an electrical issue if oil is fresh...

 

I just got an update after a longer drive by the mechanic while actively looking for faults. No strange behavior at all over 20 miles! This car just needs to be driven!
Will be picking it up asap, but it's a logistical challenge. Will update as soon as I get behind the wheel.

 

ok, So I picked up the car last night and drove it across Florida today. Tiptronic function did not work properly at all. I'm not sure what my mechanic was referring to, or this is completely intermittent or yesterday was the last time it worked like it should. I can get it to shift manually through the gears using the 1-2-3-D positions, so I think this has to be a switching or control function. I'm thinking TCU module is toast. It seems to shift properly if left in D, but I am not yet sure. I didn't give it much time in D. Mostly tried manual function.

I still need to have the fluid changed. So that will be next. Would be nice if the TCU could be tested.

 

The "TCU" will throw error codes that can be read with your scanner of choice. Since it is working in D mode, I don't think it is the control unit. You should check the micro switches first. Btw, you can unscrew the push button on the shift **** and then pull the know off. If memory serves me right, it's just friction holding it. Next, take the center console off and the whole mechanism is exposed. Easy. A good cleaning will be in order since all kinds of crud will have accumulated.

 

I was wondering how that **** comes off! I may be able to try this tomorrow.

 

I have removed the console and found it has been done before and slightly broken. Not terrible. Here are the switches for tiptronic. They look to be operating properly, but a little dirty. Without specific electrical contact cleaner what would you recommend for cleaning? Also, the switch in the neutral position, appears to place the car in manual mode, is mounted at a slight angle. Is this normal?