B5.5 Automatic, rpm varying when cruising..

Got a Passat TDI with the automatic/steptronic gearbox. When driving 50-60 mph (90 km/h) the rpm goes "up and down" in intervalls.. As if the gearbox was trying to tedt what gear it is supposed to use.. If I decrease the throttle it stops and simple decreases the speed, as it should.

Is this something its supposed to do? Its about 100 rpm's difference.. its more common under 2000 rpm then over..

Ideas?

100 rpm's IMO is a pitance. Could be tach error (does happen) even the torque converter changing from fluid drive to lock-up.

There are too many variables missing but even so my gut says you have nothing to worry about and I've fried a torque converter to the point where it barely locks up on the hwy and slips 500 rpm's.

I have noticed a similar feature. In my case the fluctuation is about 50 rpm and only occurs around 1800 rpm. In other words, vehicle speed remains the same but the rpm is different or rpm stays the same but vehicle speed may be e.g. 93 or 97 km/h at the same rpm.

I had the car checked at the dealership, and they found that sometimes and for an unknown reason the gearbox program sets the lock-up clutch to partial slip. So there is no defective component in the box/converter.

I have been experimenting with this a bit more.

- If cruise control is engaged, the phenomena happens less.
- If I reduce the throttle just a bit, it stops.

I have been noticing this alot more now, getting this fluctuation of rev's on many different speeds, all below 100km/h (60mph). If I go in highway speed around 130km/h the phenomena is gone.

Got one error on my transmission (related to torque converter), also found that my gearboxfluid was too high. Removed some but no improvement of the error.

Any ideas?

Is the torque converter changeable or do I have to change the entire gearbox?..

It could be trying to tell you something...get it looked at before it stops trying.

ltz said:

I have been noticing this alot more now, getting this fluctuation of rev's on many different speeds, all below 100km/h (60mph). If I go in highway speed around 130km/h the phenomena is gone.

Got one error on my transmission (retated to torque converter), also found that my gearboxfluid was too high. Removed some but no improvement of the error.

Any ideas?

Is the torque converter changeable or do I have to change the entire gearbox?..

Click to expand...

Can you feel the fluctuation? Is the car surging back and forth slightly?

I've been noticing the same thing with my 02 Jetta, 140K, Auto. It seems to happen most around 60 mph. Every once in a while I hear the engine rev and the RPM's rise by about 100 rpm for a split second, as if the torque converter is slipping. Not long enough for the car to change speed. I've been noticing it for about a year. Lately it has been happening more frequently (every few minutes or so). I recently had a tranny flush (done properly). It did not help.
Vag-Com indicates no engine or tranny codes.

Am I just waiting for the torque converter to kick?

rozey said:

I've been noticing the same thing with my 02 Jetta, 140K, Auto. It seems to happen most around 60 mph. Every once in a while I hear the engine rev and the RPM's rise by about 100 rpm for a split second, as if the torque converter is slipping. Not long enough for the car to change speed. I've been noticing it for about a year. Lately it has been happening more frequently (every few minutes or so). I recently had a tranny flush (done properly). It did not help.
Vag-Com indicates no engine or tranny codes.

Am I just waiting for the torque converter to kick?

Click to expand...

I agree with abc...something is amiss and it will only get worse.

I can hear the fluctuation, and visually see it on the RPM-meter. I have filmed the phenomena while driving. But those videos will probably not tell if I can feel it.

I agree, something is breaking soon on the ride. I have gotten error messages surrounding the
torque converter.

If its the torque converter, is this a separate part thats changeable or do I have to change the entire gearbox?..

TCs are separate pieces that go for a few hundred bucks.

Heard from a reputable source that there is an ECM re-flash/update on the way to dealers for a "surging" condition. This MAY be what you are experiencing (may also address the dreaded "stutter" which has been mentioned numerous times on the boards). Sorry if this is old news.

This 01V transmission as VW calls it (5HP-19 by ZF) has a common defect in the torque converter (lock-up clutch will not engage or disengage properly), but this defect will show itself as harsh vibration. In this case it seems that the problem is similar to what I've been experiencing and have reported earlier in the thread (= a bug in the software).

The torque converter can be fixed (if it is defective); there are two workshops in Finland that are able to do it and there must be such places in Sweden as well. In Finland, a brand new TC costs EUR 900 at the dealership while the repair costs EUR 300-400.

I do hope that there would be an update to the software. A few weeks back I asked for such at the dealership but at that time no update was available.

By the way, "Itz" reported that there was excess of ATF. Are you certain that engine was running (and transmission on "P") while checking the level. If the engine was not running, the TC was partially drained of ATF which would show itself as excess oil.

In regards to the torque converter issue, I too have seen common failures (though more so in Audi's). There is a seal in the TC that gets either cut or rolled when the TC is indexed on the transmission, which gives you a TC circuit/lockup fault in the TCM. I am going to guess the condition being discussed here is caused by a simple software issue (likely dealing w/ EGR ) and I will post again when I see the re-flash in person. <crosses fingers>

yes mine is damn it

Konig said:

Can you feel the fluctuation? Is the car surging back and forth slightly?

Click to expand...

Any news regarding this issue, the software flash especially ? My car seems to have become much less prone to "surging" during the past few months.

Don't believe it is just because of lower ambient temperatures as the symptoms were there throughout last winter.

Just wanted to bring this item up as my tranny keeps on doing the partial slip described above.

Does anyone know what criteria must be met so that the TCC is allowed to close ?