Tiptonic - P0740 ... HELP!

[wams]

I have a '99 Carrera. Recently, for smog test the CEL decode displayed O2 sensor fault and also P0740. Replaced the O2s and cleaned the MAF (per posting/response from Loren on how to clean the MAF with MAF cleaner) and smog passed before the CEL came back on. About 2 days ago, the CEL came on (did not get to check it yet) and suspect it to be P0740, added with a vibrating noise. On stationary mode, it does not produce the noise. When I am driving, the noise is there. It goes away when I press the gas paddle again cames back when I let go the gas paddle and coast. While I was driving (coasting) I shifted the tiptronic from "D" to "N" and the noise was gone. I am suspecting the the transmission ... with the torque converter, along with P0740 (which was there before) is the cause for the noise. Can someone (including Loren) from the forum shed some light on me in regards to this vibrating noise. I guess I will have to break down and take it to Pioneer Porsche in San Diego. Or, is there other reasonable shop around in San Diego area? Thanks.

Edited July 25, 2009 by wams

[Loren]

P0740 Fault, torque converter clutch - present

Possible causes:

- ATF supply

- Torque converter

- Pressure regulator 4 (hydraulic)

- Electrical triggering to pressure regulator 4

- Hydraulic control unit

I would start by having the fluid level checked.

[wams]

P0740 Fault, torque converter clutch - present

Possible causes:

- ATF supply

- Torque converter

- Pressure regulator 4 (hydraulic)

- Electrical triggering to pressure regulator 4

- Hydraulic control unit

I would start by having the fluid level checked.

Thanks Loren.

Also, I forgot to mention that : 1.) sometime when the gear shift from from 3rd to 4th in manual mode, it jerks and almost like jumps into the next gear, with a "thugg" noise; 2.) in auto mode, shifting from 4th to 5th has a hesitation, takes a second or so to shift into the higher gear, while the RPM goes up. Thanks.

[whelton]

P0740 Fault, torque converter clutch - present

Possible causes:

- ATF supply

- Torque converter

- Pressure regulator 4 (hydraulic)

- Electrical triggering to pressure regulator 4

- Hydraulic control unit

I would start by having the fluid level checked.

Thanks Loren.

Also, I forgot to mention that : 1.) sometime when the gear shift from from 3rd to 4th in manual mode, it jerks and almost like jumps into the next gear, with a "thugg" noise; 2.) in auto mode, shifting from 4th to 5th has a hesitation, takes a second or so to shift into the higher gear, while the RPM goes up. Thanks.

I don't want to cause you any stress but I too have a 99 Carrera with 80,000 kilometers on it and here is what just happened with mine. I was noticing a vibration and had planned to replace the engine mounts. About 6 weeks ago I had one case of a really hard downshift from 3rd to 2nd and thought nothing of it. I took it for a long drive on Saturday (about 200 kilometers) and all was great. Then Sunday it started slipping in 2nd gear when accelerating and it also was slipping in reverse. I took it out for a test drive and when I stepped down on it to see if it was kicking down properly, it hit so hard in second it shook the whole car. Felt like I had been hit by another car. The slipping continued also. I took it in to my regular service guy first thing Monday morning and he suggested that he would first check the computer and possible reflash it. There were no error codes at all. I asked that he replace the fluid while he had it there. While I was waiting from my ride to work he was draining the fluid and I heard "the fluid is really black, I see silver in there". Not something you want to hear. When they took the pan off there 1/2" x 1/4" pieces of metal in the pan. It has been sent in to be repair by a transmission specialist here. Two of the drums have broken up. Apparently it can happen with that particular transmission. It's almost the same as the one in a 330 BMW where it tends to happen more often. I'm looking at about $8,000 ($6,500 USD) for the total repair bill. I'm doing the 100,000 k service while the engine is out of the car and replacing the engine mounts and transmission mount while I'm at it. Believe it or not you have to buy part of the transmission casing just to get the mount. And he's going to clean my engine really good while it's out. I have to laugh about it to keep from crying because I have just spent $7,500 on it with a new top, new wheels, led tail lights, etc., etc. It looks really good sitting in the garage.

Anyway I'm sure your problem won't anywhere near that bad, but I would be curious to know if the above suggestions solve your problem. I just bought the car 2 months ago (no warranty) from someone I know and he only drove it about 15,000 kilometers in 3 years. It has never been to the track or anything and he drives like an old lady. I've never run it hard either. I had planned to use it as a daily driver. I'm not so sure that was good idea. I'm not convinced Porsches are cut out to be daily drivers. I've got about 40 traffic lights on my commute so maybe it's just too much shifting for it. I'm back to driving the dog car ($1,000 Mitsubishi Hatchback with 210,000 kilometers on it and no back seat) for the next 5 weeks. Good luck with your car!

Cheers,

Will