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Discussion Starter · #1 ·
1st, the history. I use Tiptronic almost exclusively (better mileage with lower rpm shifts).

70K bought used, fluid/filter change with Mobil. No change, shifted like stock.

100K , fluid/filter change with Redline D4. Smoother shifting, much smoother downshifts into 1st. 2 long road trips this summer (9000 miles) including lots of mountian driving, no problems.

115K (2 weeks ago), noticed the rpm float/climb while upshifting under part throttle. Slightly worse when warm, it would rise up to 400rpm. TC stayed locked while in gear.

Last Sunday, out for a Sunday Morning Drive (think canyon run). At 90-100mph, TC starts to unlock in 5th and revs climb 400 rpm. Shut down for lunch, normal speeds on the drive home and it seemed fine.

Yesterday, take it Sipes, 40 miles up, 20+ hard miles while being scanned. All seems normal, no trans codes just the usual Cat code and a new secondary air flow problem. TC shows locking when it should. Trans temp rises to 90c and stays (as it should).

Drive 40miles home in near stop and go highway rush hour traffic. Get within 10 miles of home and traffic opens up. Get up to 60 and notice revs are climbing too high. 2500 at 60 and it jumps to 2800 if I push the gas. The rest of the drive home, the TC will not lock in any gear.

Drive to work this AM and car is fine :crazy:

It seems similar to this W8 thread about a failed TC.
http://www.passatworld.com/forums/showthread.php?t=237369

I guess we are taking the Golf on this weekend's trip to Austin.
 

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While I'll be the first to admit that I know NOTHING about the fluid flow through these trans/converters, I DO know what happens when a failing converter is allowed to run in a Dodge 46RE trans. $2000 worth of rebuild due to metallic fragments scattered throughout the clutches, bands and valve body...
 

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Dude, that sucks. I had to have mine replaced on my 03 W8 6 months ago. Called the dealer, thye wanted $4000 to replace, then found a GREAT Indy, $2000 which was still hard to swollow!
 

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Discussion Starter · #4 ·
I don't know if the TC is failing or just failing to lock. From what I have seen, all 4MO cars tend to eat converters. The S4 and W8 were the worst. A local Audi mechanic says a seal gets displaced in the TC.

So far, the TC is just failing to lock after 100 miles of hard driving. The scan showed normal locking while driven yesterday and it was not until driving for an hour in rush hour traffic that it got worse.

Since I work less than 6 miles from home, it may take a while for it to show up again. I guess I have to see if Sipes is brave (or stupid) enough to go on the next SMD with me. I am sure it will show up again.

If it holds up locally, I may not bother to repair it. I get a new car in 2 years either way (that's when both cars are paid off). I would rather not drop a 4MO trans in my garage, but I will not pay to have it done. I would even be willing to do a manual swap if I can a donor car.
 

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I've never had to go into one of these transmissions but there has to be a lockup solenoid that controls the torque converter lockup I would imagine. It really sounds like the solenoid is getting hot and then failing. Usually a mechanical failure in the torque converter will not come and go so erratically like yours is doing, especially where lockup is concerned.
 

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Discussion Starter · #6 ·
Yeah, I was thinking it would be an all or nothing on the lockup. My only worry is that the solenoid is getting a bad signal from the TCU. I did not have a code for a bad TC solenoid, so I will wait and see if it gets worse.
 

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with the vag-com when i was watching the variables as we were around we had only one sudden opening of the TC at an odd time. trans temp was at a 90 degree Celsius.

also, i noted one of the solenoids listed in one of the measuring blocks as "solenoid 7" (it's in block 3, 4 or 5... same one as tcc status) the numbers we were getting were along the lines of "0.000 A" was open "0.300 - 0.638" was listed oddly as "regular" not sure what it means. and the TCC closes was at a variable of "0.700 A" and above slightly more, but still within the .7 range. now, i don't know if these are amperage measurements, but these are the most conclusive pieces of data i was able to extrapolate from the car in the drive.

pz, if you're ok with it, want me to post up a link to the data logged?
i figure L1tech, or others may be able to give a little better insight.
 

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Discussion Starter · #8 ·
Yeah, you can post it up but I don't know if it will help unitl we catch it in the act full time. Then we can see if the sensor is sending the wrong signal or if the TC is ignoring it.
 

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If I make it over to the shop today I will see if I can dig up a little more info on whether this uses a tcc solenoid or not, I have heard that it may be purely mechanical. The readings you are seeing are amps of the different solenoids and they should change as the car goes into different gears. If you have the the data log I would love to have a look at it, the more info the better.
 

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Discussion Starter · #10 ·
Yes, there is a soleniod and it shows a set reading with the TC open, active and locked. It appeared to be correct, but the car did not act up until the drive home. If you PM me your email, I can send the log.

It seems to be fine on my short commute except for the little blip in rpm on upshifts.
 

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Discussion Starter · #11 ·
Went on a 375 mile round trip Sunday at normal highway speeds (75 indicated) and with less than a 30 minute stop halfway, the car was fine. I can only guess it is overheating and I will install an extra trans cooler and see how it hold up.
 

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Some slippage in the TC is normal. There is a Reg mode that allows for up to 510rpm of slip in gear. To my knowledge it was put in for fuel economy and comfort purposes in that it keeps the tranny from downshifting if there is a small throttle application.
 

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Discussion Starter · #13 ·
Some slippage in the TC is normal. There is a Reg mode that allows for up to 510rpm of slip in gear. To my knowledge it was put in for fuel economy and comfort purposes in that it keeps the tranny from downshifting if there is a small throttle application.
In Tiptronic, the TC locks in 3rd, 4th and 5th. It should not unlock unless the throttle is floored. The upshifts were quite firm, with just a quick drop in rpm.

When this problem started, the rpm would jump just a little when I upshifted. The warmer the car, the higher the jump (up to 200 rpm). Now that it is cooler (45 at night), the car is acting just like it used to before this started. Nice firm shifts with no rpm blip.

When the TC unlocked on the high speed drive, it was in tiptronic and only at part throttle. Temps were in the mid 70s.

When the TC unlocked after the rush hour heavy traffic, it was in all gears at any throttle input. It did not lock at all for the last few miles. Testing prior to the traffic showed the trans at temp, but not overheating.

The 375 mile trip was in 70 degree weather and the TC was fine.

I think the trans is overheating when used heavily. I don't know how why it did not show up on testing, maybe it was not long enough to overwhelm the stock trans cooler.

With as many W8, S4 and 4MO trans that have failed, I would rather add an external trans cooler to the car now.
 

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Maybe next time you do a fluid change in your tranny use an ATF that does well in high heat. A tranny cooler is never a bad idea.
 

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Tranny cooler is a good idea as is the fluid change. As per the 200rpm blip, keep an eye on it. The viscosity of the fluid will obviously change a little as it heats up. While this is just a guess on my part, if the fluid is loosing viscosity or 'thinning' it may not create as much drag between the halves of the TC or may decrease the line pressure. Either way, if it starts frequently slipping between shifts look for a new TC (that's what I'm doing:thumbdown) check out IPT
www.importperformancetrans.com a custom TC only costs $695. I know the install costs suck but at least you'll have some peace of mind and some extra WHP as a result of them making a more efficient TC.

edit: from talking to various sources it appears that the internals of these trannies are quite rugged, it's the crummy VW spec TC's that fail
 

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Discussion Starter · #16 ·
Update: I finally got the trans to throw a code.

1 Fault Found:
17125 - Torque Converter Clutch: Stuck OFF / No Power being transferred P0741 - 35-10 - - - Intermittent

The TC is now unlocking after 10 minutes or less depending on driving style. Even while locked, it will unlock at half throttle or more. It still is a smooth transition, just a 200 rpm climb at 60 and more with throttle. I guess I will change the fluid and filter when I have a chance and see if that helps.

If the TC is fried, I will change it myself, so no labor cost involved. I just don't feel like pulling it all apart as I have enough to do right now (5 timing belts and a set of coilovers in 3 weeks time, plus 54 hours a week at work).
 

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like i said pz, i can change my work schedule to help you out with whichever route you take...

either way, it's another lesson for me in how our cars are configured :p
 

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Discussion Starter · #19 ·
Thanks for the PM.

Thomas, when I have some time free, we need to take another drive and watch the solenoid values as the TC tries to lock. Then I can see if the soleniod is good before I pull the pan for the fluid change.

And now all 5 timing belts are within 2 weeks of each other. 1 down, 4 to go in the next 9 days.
 

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Nice!

i really wish the 01v really had some pressure sensors built into it... having those would be nice for diagnosis, or even the hydraulic ports similar to what gm does for line testing.
 
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