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Discussion Starter #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.
 

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Discussion Starter #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



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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
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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

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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

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

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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.
 

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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.
 

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Discussion Starter #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...
 

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Discussion Starter #8
Thanks for that link. I ran across that a few months ago and forgot about it. It looks like a real pain but should fix my issue based on what I read.
 

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Discussion Starter #9
I got a generic VCDS cable last week and plan to register the software for more features, I'm hoping to recode the TCM for "sport mode", and see if that changes anything for the better. I'll post with updates.
 

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I got my new Ross-Tech interface today, and on a test drive watched the gear selections on the laptop as I slowed down. It does in fact shift down through the gears, very smoothly, but I was wrong in thinking that it did a 5-1 shift on coming to a stop.
 

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Discussion Starter #11
I've always been able to tell, though it is quite smooth. Just frustrating this is going on, it's an otherwise smooth shifting transmission.
 

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Working on the valve body is really not that difficult, if that's what you end up needing to do. It's just messy since you'll have the fluid drip all over you as you take it down, but if you let it drain over night and then remove the valve body, it will be a bit less messy.
 

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I don't know what the problem is exactly but I've been experiencing the same problem and yesterday she gave a clunk and now won't come out of fourth gear. Get this looked at professionally immediately.
 

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Discussion Starter #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...
 

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Discussion Starter #17
Wow, just called a local company that does work on ZF transmissions and was told they do "can not" order individual solenoids, they'd have to order as a set. With that and labor I'm looking at roughly $1200. I think I'll keep calling around...
 

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Discussion Starter #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.
 

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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.
 
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