Auto tranny help -- calling all VW/Audi folks!

"Ash78, voting early and often" (ash78) 08/26/2014 at 15:33 • Filed to: None

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Hey crew,

The wife's Passat has auto tranny ZF model 5HP19FLA, which was pretty common in late 90s to early 2000s AWD Audi and longitudinal VW cars.

A few months ago, she noticed her 2001 Passat wagon (V6, only 107k miles) acting strangely on long drives, long hills, or whenever the tranny was asked to shift repeatedly. We couldn't replicate the problem while I was driving until recently, and it was definitely odd — when accelerating, the car wanted to stay in 2nd and not upshift unless forced into Tiptronic (manumatic) mode, at which point everything would act normally. Sometimes this would happen in 3rd, but usually 2nd. Further, the car also suddenly "learned" how to downshift into 2nd or 3rd when slowing, which is another new behavior that coincided with the above strangeness.

I already had the an ATF fluid/filter kit sitting in the garage, so I did the full change about 2 weeks ago...no improvement. In fact, as time goes on, it seemed to be getting more frequent. There are no tranny codes in VAG-Com at all, and otherwise the tranny is as smooth as it's ever been. I've tried logging MAF and solenoid behavior, and nothing is terribly off. The indy mechanic sent it to his tranny expert who simply said we needed a new tranny, $3500, and that 2 nd gear was slipping due to high temps. However my confusion is that the tiptronic mode still works fine – it forces a torque converter lock, but otherwise should use the same valves and solenoids as normal automatic shifting. This makes me think the problem might be hidden in a sensor or control module somewhere, but no error codes?

I've got a reluctant appointment with the dealer on Friday that I'm not looking forward to. This car is otherwise in great shape and I was planning to inherit it in a few months when the wife moves up to a van. Now I'm having serious reservations….

Thanks in advance for any help, this is a last ditch effort in case my fellow VAG-o-philes have seen similar behavior or know of a solution.

Chris Clarke > Ash78, voting early and often 08/26/2014 at 15:36

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Got a 98 A4 had the same issue. Bought a used MAF off Ebay. Problem solved. Can't remember if I had MAF CEL? Might have my old logs.

Ash78, voting early and often > Chris Clarke 08/26/2014 at 15:39

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Thanks...brand new ones are only $100-$150, so I might try that route. I've heard a handful of people aaying the MAF could be at fault and is often ignored when it comes to emissions/tranny problems (in my '98, it failed and caused all kinds of stalling). Tonight I'll try cleaning the MAF and driving with it unplugged to see what happens. This used to be my specialty...search for MAF cleaning Passat and my DIY and data logs come up. Oh, to have free time again!

Yowen - not necessarily not spaghetti and meatballs > Ash78, voting early and often 08/26/2014 at 15:39

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Was the tranny person that looked at it a VW expert? I would get an expert opinion/quote/diagnosis.

On my 97 Jetta resetting the adaptive learning got me out of trouble for a while, but the slipping eventually resurfaced.

Ash78, voting early and often > Yowen - not necessarily not spaghetti and meatballs 08/26/2014 at 15:41

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No— the indy is a brand specialist, but the tranny shop was generic. That's why I wanted the second opinion from the dealer. My service advisor loves this car and is pretty honest with me.

Chris Clarke > Ash78, voting early and often 08/26/2014 at 15:45

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Found my logs from a couple years ago. MAF code wouldn't show up everytime even when the tranny went limp. Never got a tranny code either even though it suggested I check. There was also an occasional Load Calculation Cross Check error caused by a bad MAF which will affect the trans. If you could find a MAF to swap, maybe from your indy shop, that'd be a cheap/quick diagnosis.

16486 - Mass Air Flow Sensor (G70): Signal too Low

P0102 - 35-10 - - - Intermittent

18032 - MIL Request Signal Active (Check TCM for errors too!)

P1624 - 35-00 - -

17549 - Load Calculation Cross Check: Implausible Value

P1141 - 35-00 - -

Ash78, voting early and often > Chris Clarke 08/26/2014 at 15:48

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Thanks, the faulty engine load calculation could definitely mess with the tranny. In my two previously bad MAFs, I never actually got an MAF code, even though it was the problem. Weird.

Chris Clarke > Ash78, voting early and often 08/26/2014 at 15:55

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MAF stands for Mystery As Fuck.

jariten1781 > Ash78, voting early and often 08/26/2014 at 15:55

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Did you try the go-to reset? Not sure it works on that model, but it does on a ton of VAG autos. It clears all the adaptive shift points, resets everything to default and resyncs with the throttle.

Key to accessory

Throttle full in for ~10 sec

Key off while still holding throttle

Release throttle

Key to accessory - wait 5-10 minutes without touching anything

Startup

RallyWrench > Ash78, voting early and often 11/24/2014 at 14:48

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As others have suggested, the MAF is a good place to start, as they can cause all kinds of no-code driveability issues. The load calculations that the TCM uses for shifting are based mostly on throttle demand, MAF rate, vehicle speed, and temperature.

When checking the MAF, you should see 2.5-4.0 grams per second or so at warm no-load idle, and around 152gm/s at WOT near redline, or about 80% of the engine's rated output. When logging it, log throttle angle (block 60) & the MAF simultaneously, and have the trans in tiptronic mode so it'll hold one gear. Start the log, give slowly & steadily increasing throttle from 0 up to WOT (but not into kickdown), then stop the log. Review it & make sure both numbers correlate, with no peaks or valleys in the MAF reading. The processing speed might not catch everything, but having only 2 fields to log will help.

You can also log the trans, comparing engine speed to trans input speed to see if the TC is locking properly, although they're pretty damn good about setting a code when they don't. These things don't often have control or valve body/solenoid issues, and when they do fail, they usually flare between shifts. When the transmissions are flat worn out, they tend to lose Drive or Reverse.

Ash78, voting early and often > RallyWrench 11/24/2014 at 15:16

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Thanks for that advice, did all of that several times over, unfortunately, and all of the professionals are stumped.

It stopped acting up in the cooler weather (in fact, it runs perfectly now) and since you read my Odyssey post, it's worth noting that the Passat wagon is now my car. Maybe the gremlin is gone, maybe it'll crop up in the spring again...