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Tiptronic 5-4 abrupt downshifting

14K views 36 replies 13 participants last post by  Spottedbat 
#1 ·
I searched this a couple months ago and didn't really find anything useful. I've been noticing for a few months that when the car is in 5 and I let off the gas, sometimes it seems like it holds gear longer than it needs to and downshifting into 4 is abrupt. It does this regardless if I do it manually or allow the trans to downshift itself. This is the only gear it does this in, and I found if I downshift sooner than it normally would (keeping RPMs up) it has no problem. It's like it isn't downshifting when it needs to and when it realizes it's held gear too long, it suddenly jumps down into 4. I topped off transmission fluid with correct stuff a month or so ago, and that didn't do anything. I'm not sure if it's a solenoid or something else failing, but it is upsetting and I'm hoping it's a relatively simple fix. Do you think maybe a TCM flash is in store? Any ideas/thoughts are welcomed.

Mike

EDIT: It only does this abrupt downshift if the trans doesn't downshift quickly enough, other times you'd never even feel the downshifting. It's been a solid trans so far with 119k miles on it with no issues until this.
 
#2 · (Edited)
I had a neighbor scan the car with VCDS a while back and there was one fault found with the trans, though I'm not sure if this explains what's going on:


Sunday,21,April,2013,20:00:38:24600
VCDS Version: Release 11.11.5
Data version: 20121222



--------------------------------------------------------------------------------
--------------------------------------------------------------------------------


Chassis Type: 3B - VW Passat B5
Scan: 01 02 03 08 15 16 17 19 35 36 37 46 47 55 56 57 58 75 76 77


VIN: WVWPD63B44E170647 Mileage: 189900km/117998miles
-------------------------------------------------------------------------------
Address 01: Engine Labels: 06B-906-018-AWM.clb
Part No SW: 4B0 906 018 DP HW: 8E0 909 018 A
Component: 1.8L R4/5VT G 0002
Coding: 0016551
Shop #: WSC 14130 664 403206
VCID: 72E00F6B6ECF3988278

No fault code found.
Readiness: 0000 0000

-------------------------------------------------------------------------------
Address 02: Auto Trans Labels: 01V-927-156.lbl
Part No: 3B0 927 156 AM
Component: AG5 01V 1.8l5VT USA 1212
Coding: 0001104
Shop #: WSC 05311 000 00000
VCID: 71E200676BC90290DE2

1 Fault Found:
17095 - Transmission Fluid Temp Sensor (G93)
P0711 - 003 - Implausible Signal - Intermittent

-------------------------------------------------------------------------------
 
#3 ·
I wonder if that fluid temp sensor reading is causing the transmission to act a bit strangely. I don't know whether the shift or torque converter lockup controls act any differently on cold cycle than on warm, but I suppose they could -- I'll have to defer to an expert on this question.

I have noticed that the tip seems to have some sort of engine braking logic between overdrive (5) and direct (4), so this may be getting confused.
 
#4 ·
I've been noticing for a few months that when the car is in 5 and I let off the gas, sometimes it seems like it holds gear longer than it needs to and downshifting into 4 is abrupt.
When you say "let off the gas", do you mean that you expect the trans to downshift right away? I've never watched the solenoids shift on VAG-COM while driving, but I'm pretty sure that on my '96 A4 at least, if I am in 5th, and let off the gas and coast, the trans doesn't shift at all until the engine is almost to idle speed. The trans seems to then shift from fifth to neutral, and the engine speed drops to idle as the car coasts to a stop. Just before stopping, first gear engages.
 
#6 · (Edited)
Filter and fluid both done at 75k, and a drain and fill at 100k. Both with Pentosin. I don't expect an immediate downshift, but I do expect it to not be abrupt when doing so. It's like it stays in 5th a tad long and realizes it but when rpms aren't where they should be. Make sense?

When I let off the gas and feel the trans going too long before the downshift, I look at the tach and it doesn't downshift until 1100-1200 RPMs. IIRC, when it shifts properly, it does so at slightly higher RPMs, like maybe 1400 or so...
 
#23 ·
Depending where you are in Raleigh, I've got a full blown Ross-Tech HEX-CAN-K VAGCOM cable. I'm home all summer, and I'm sure we could work something out. Also... they have a bunch of B5.5 Passats over at the LKQ in Clayton right now, and 3-4 B5 (up to 00) at the Durham one. I've found using their website is the easiest way to see what they have. Just throwing that out there in case you consider grabbing any "cheap" alternatives before getting new.
 
#16 ·
Just called the dealer and they want to have it in for diagnostic (though I have the codes and data) for $100, then can let me know what's going on. It sounds like going through the dealer will be pricey (no shocker), primarily because they want to start at tier 1 troubleshooting, though I've investigated already and based on what I've read lately it isn't mechanical, except for when electronically it fails, forcing the mechanical side to also intermittently fail. I'm mentally and probably time-wise not prepared to do this myself (having a lift would be awesome here), but I'm not sure I want to pay the dealer a ton of money. He said they do not do overhauls, but if this is electronic/solenoid, he believes it should be something they do.

I guess another option is to find a local place that has experience with ZF transmissions...
 
#19 ·
Wow, just read this online from March 2004 (clubtouareg.com):

Dynamic Shift Program (DSP) - that is what VW calls its addaptive trasmission.

What does it do? Simple ... when you drive aggressively, DSP keeps the revs higher gears lower; when you are docile, DSP keeps revs lower and gears higher. How long does it take to "learn" - in my experience a few minutes..

I've also encoutered what I perceive as the DSP learning badly ... See the Downshifting after a long drive topic in the Problems/Bug forum.
In short, docile 50mph+ driving for an extended period of time makes the DSP very docile. Too docile. So much so that DSP becomes hesitant to downshift to the point that the revs reach stall range, and the engine and tranny have a momentary dispute manifested as a disconcerning "clunk" between 5th and 4th gears. I hope VW issues a new flash for the DSP, or one of these days, my Touareg and tranny will be separated.
 
#20 ·
Try this place:
MZF-Bayer Transmissions

I didn't order solenoids from them so I don't know for sure, but I got an o-ring and the paper gasket, where two other shops that I tried wanted to sell me an entire kit of parts. When I tried my local dealership, they wanted to replace the entire valve body as they didn't do any work on them nor able to order any parts for it. But hopefully they could at least tell you what exactly is the problem.
 
#21 ·
Using VCDS-Lite last night, I did verify the temp sensor is working. It reported 42*C, which is roughly 107*F. I took the car for a drive through a new neighborhood late last night and saw the temp come up a bit, though I didn't record it so I'm not sure how high it did go. I changed the soft coding in the TCM from 1104 to 1134. The car is still doing the same thing (didn't think it would change the behaviour, but it was worth a shot). It is doing it less frequently, so I'll keep a close watch on it over the next few days, but I'm thinking it may be new valve body time. I'll ride it out as long as I can.


As mentioned in other threads through the years, changing the soft coding from 1104 to 1134 did eliminate the kickdown while in tip mode, and it has allowed the car to hold gear longer while driving in D. Also it does more readily downshift with less throttle input. It isn't night and day difference, but noticeable for sure. Driving it today was more noticeable than last night right after I did it. I was going to do a TBA, but cannot with VCDS-Lite. I'll register it to be able to have a lot more features, but I'm glad I can at least see the codes and clear whatever may be present.

Edit: I did forget to mention I've had this code for at least 2 years now. I was in Winston-Salem at Everything Euro, and was told it was common with these cars and not to worry about it since it shifted just fine. So, I honestly don't think this code is indicative of the symptom. I'm really hoping a new n91 (n215 pressure valve) on the valve body is all it needs.
 
#24 · (Edited)
Thanks for the link, PZ. And thanks for the offer, vb... I'm pretty much available every weekend, weeknights who knows with RTP traffic, etc.

After driving the car with the TCM recoded, there is no difference in the harsh downshift. I was on vacation last week, so it stayed parked for a week. At least that's one week of harsh downshifting I didn't have:)
 
#25 ·
I changed the coding from 1104 to 1134 then to 1034, and honestly I can't tell the difference except when in tiptronic. I may just not be pushing it enough to tell, but it's at least not going to hurt anything.

One thing I've noticed this week and it has worked this way each time is if I press the accelerator in auto or tip just before downshifting, it downshifts properly. For instance, I'm cruising in 5, let off to slow to a stop, but then press the gas again then downshift and it's butter smooth again. If I let it downshift without me doing this, it may be smooth or may not be. It's like keeping torque applied keeps it happy; let the power go away and it may be unhappy and jolt upon the downshift...
 
#26 ·
Another update: I ordered the n91 solenoid for the transmission's harsh downshift, which from reading multiple threads on multiple sites seems to be the most likely culprit and is the most common fix to this exact issue. I still need to order fluid, gasket, filter, etc. but I'm hoping to get this part replaced next week. I just wanted to update for anyone that may be experiencing the same thing. Also to note, this part has gone up in price a little, and with included overnight shipping came to $151. Not cheap, but it is from ZF Germany's US distributor, www.thectsc.com. If anyone is interested, they also carry ZF Life Guard 5 fluid, which is the correct one to use in our 5 speed tiptronics, though I opted to not buy at roughly $18/liter plus shipping.
 
#27 ·
"1 Fault Found:
17095 - Transmission Fluid Temp Sensor (G93)
P0711 - 003 - Implausible Signal - Intermittent"

I suggest you check the Temp Sensor (G93) while doing the other work. It appears it has an Intermittent fault or connection.
I wouldn't expect smooth shifts if it doesn't know the oil temp.
 
#28 ·
What's your reasoning behind this expectation? Just curious.

I have seen that this 17095 fault is fairly common with no driveability symptoms even for long periods (tens of thousands of miles).

I have also heard that this temp sensor which I think is an NTC thermistor is integral to the solenoid wiring harness (01V 971 661 B) at around $300+ cost.

It would seem like the cause would be some kind of intermittent connection issue, but there's not a lot of data out there from people who've replaced the harness to fix the 17095 fault and their observed 'improvements'.

I just thought I'd ask the question of whether you knew something different.

Care to elaborate further?
 
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