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Discussion Starter · #1 ·
Hi. I hope to get some help with this downshift issue. I have posted about this before, but now I have more info. First a little background. The car is a 2004 VW Passat V6 4motion wagon with tiptronic and has 142k miles, runs like a champ other than this issue. This is some of the work that was just completed in the last 3 or so months. Timing belt service with all the extras, transmission flush with fluid level checked at proper tempreture, and front and rear differential fluid change. Also had a VAG-Com check, and there were no transmission errors or faults found. Checked around TCM, and it’s all dry.
This is what’s she does. Start driving, everything is smooth. Upshift, downshift, no problems. About 5 minutes into the trip in city driving, as I come up to an offramp or stop sign as I slow down with the foot off the gas, she will jerk as she shifts from 5th to 4th gear. The rest of the downshifts are smooth. This happens even in tiptronic mode. It gets a bit worse and worse every time you come up to a stop sign, and it feels like that the axle is being hit with a sledgehammer. Now - the kicker. As I am slowing down, if I go in to tiptronic and just before the dowshift I would hit the gas and manually shift to 4th gear, then the downshift is smooth again. As long as there is load on the driveshaft, the downshift is smooth again. Once I take my foot off the gas and coast, the downshift becomes rough about 80% of the time. Upshifts are always smooth.
Thanks for any input.
PS. I will change the torsen drive fluid shortly just in case.
 

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2002 V6 trip with about the same miles and the same slamming shift. My local Indy repair shop said the Mass Airflow Sensor was throwing codes and miss-fires on most cylinders. They changed the MAS and it hasn't slammed gears in days. Sounds odd that the MAS could do that to shifts...
Good luck, let us know the fix.
Philip
 

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Did you check with the dealer to see if there is a software update to fix this? There was one for the B5.5 4MO, but I don't know which years it applied to.
 

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Discussion Starter · #4 ·
Thanks for the replies. I did ask the dealer about the TCM reprogram, I even gave the printout of the bulletin. They will call me back once they find out more about it.
Interesting idea about the MAF sensor. I did replace the plugs and installed new ignition wires about 4 months ago. No misfire codes, but I will investigate.
Keep those ideas coming!!!!
 

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Is the software update pre or post the exhaust shield recall? That's the last time my '02 has been at the dealer. How much are they charging for to flash the computer?
 

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This is what’s she does. Start driving, everything is smooth. Upshift, downshift, no problems. About 5 minutes into the trip in city driving, as I come up to an offramp or stop sign as I slow down with the foot off the gas, she will jerk as she shifts from 5th to 4th gear. The rest of the downshifts are smooth. This happens even in tiptronic mode. It gets a bit worse and worse every time you come up to a stop sign, and it feels like that the axle is being hit with a sledgehammer. Now - the kicker. As I am slowing down, if I go in to tiptronic and just before the dowshift I would hit the gas and manually shift to 4th gear, then the downshift is smooth again. As long as there is load on the driveshaft, the downshift is smooth again. Once I take my foot off the gas and coast, the downshift becomes rough about 80% of the time. Upshifts are always smooth.
This is EXACTLY what I had, including the same way to get around the annoying slamming from 5th to 4th. My issue was a bad connection to the MAF, which I fixed and the transmission went back to shifting like butter once again. My CEL came on for this and I could scan a code which told me the MAF had inconsistent voltage readings.

Another member from another board also had the EXACT same issue, but his resolution was replacing an internal solenoid (N91 I believe) on the tranny valve body. This code would only be able to get scanned by a dealer or by VAG-COM.

You are not getting codes which makes things hard to deduce. The 2 examples above are possibilities, but other possibilities include a bad TCM, bad connections from TCM to the tranny wiring harness, bad connection from the tranny wiring harness to tranny valve body, bad solenoids in the valve body, a bad rubber 'o' ring or plug in the valve body.

I would going throught the easy and cheap fixes first, finally arriving at the possibility of getting a reconditioned valve body; roughly $700, but it will include the option to customize shifts to be harder and crisper if so desired. Unless you like the adventure of rebuilding your own valve body. Mister T did an excellent writ-up on his valve body strip and rebuild....


Dave. :)
 

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Discussion Starter · #7 ·
Thanks for a great reply!!:) Now I have something to work with. Dave, do you think you can reply or PM me on what steps you took with the MAF as far as finding the bad connection? Thanks again! You guys ROCK with this forum!
 

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Thanks for a great reply!!:) Now I have something to work with. Dave, do you think you can reply or PM me on what steps you took with the MAF as far as finding the bad connection? Thanks again! You guys ROCK with this forum!
[Embarassing Confession On] I knew I had damaged the wire becuase I mistakenly pulled it out of the connector when trying to remove the electrical block connector from the MAF unit. [/Embarassing Confession Off]

As soon as this happened I got a CEL and my OBD II reader threw a code. The tranny was getting worse and worse as time went by, until I found the wire with the special end connector and soldered in a new wire. The moment it was plugged back in the tranny magically went back to perfection.
 

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Discussion Starter · #9 ·
Cleaned the MAF sensor yesterday. Did not improve downshift issue, but did it ever improve throttle response.Gave her a workout on the freeway today and was REALLY impressed how she was accelarating from any speed. Best 12 bucks I spent in a while.:thumbup: I think TCM reprogram is next.
 

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Discussion Starter · #10 ·
So I just finished changing the torsen drive seal and fluid change. Unfortunately it did not help with the problem at hand. Still waiting for the reprogram of the TMC. Will report back.
 

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The TCM uses MAF data (and other data) when making decisions about when and how to perform shifts. It's a computer controlled transmission. Like with any software, garbage in... garbage out. That's why a bad MAF can cause it to shift strange.
 

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I had a problem withe my 2001 passat v6 - after cleaning the maf with carburetor cleaner, I suddenly had a loud clunk going into drive, and also when shifting from 4 to 5 gear. After using this forum, went out and bought real maf cleaner. Cleaned up the maf with the cleaner, shifting problems gone! Moral: don't ever use anything but maf cleaner on a maf. I saved so much money by not having to buy a new maf!
 

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I'll bump this thread; some of you may have read my thread about the same thing. I have no codes at the moment, but I'm suspecting either MAF sensor or n91 solenoid. As the OP, if I apply a little throttle just prior to downshifting from 5 to 4, it's butter smooth. If I don't, it may or may not be smooth. It seems to be happening more frequently now if I don't apply more throttle, but sometimes when I think it's going to jerk into gear it's really smooth, and other times it hasn't done it in a while so I almost forget until it quickly reminds me it hasn't cleared up yet.

If any of you reading this thread have resolved this, please let me know. I have VCDS-Lite, so I could use that while driving if anyone local wants to ride along with the laptop...
 

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I have a similar problem with my B5.5 V6 FWD Tip 132K as it shifts from 3rd to 2nd gear when coasting to a stop. The car is well maintained. Replaced MAF but no improvement. I also have a delayed upshift from 1st to 2nd when its cold but that can be fixed temporarily by inserting the key, turning the car on but not starting, then pressing the gas pedal to the floor for 10 seconds then remove the key. After I do this TBA the car will upshift as it should when cold for 2-3 days then it goes back to the delayed upshift. I cleaned the throttle body but no improvement. And all the vacuum lines are new and there is no CEL. When the tranny warms up the harsh 3-2 downshift become more noticeable. So I'm wondering if it is temperature related. The engine reaches 190 degrees after 5 minutes of driving and it seems to stay hot for a long time after I finish driving for at least 30 min. It stays hot over 3 hours. I just did a G12 flush and set the mix to 70/30 but no improvement in temp. I have another 5 liters of Pentosin ATF to put in the tranny for my 3rd drain and fill. If I can find a valve body kit for the EZZ tranny I may rebuild my valve body next month. I wonder if the adaptive learning of the tranny is causing the problem as the TBA seems to offer some temporary relief. The downshift is not that bad, but in stop and go traffic it is noticeable. I'm not sure if there may be hidden codes in the tranny that are only visible with a vagcom. Seems I'm running out of things to try. Anyone have any ideas?
 

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50/50 is probably a better mix to use for coolant. Water carries heat energy better than G12 does. A 70/30 mix actually reduces the cooling capacity of the system (ability to move BTU's).

VAG-com can interrogate the transmission control module specifically. See if anyone in your area has a setup and will scan it for you. Maybe ask the local VW Audi car club community.
 

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Mine doesn't seem to be temp related, and since I cleared the code it hasn't come back. The code was:

17095 - Transmission Fluid Temp Sensor (G93)
P0711 - 003 - Implausible Signal - Intermittent

The common fix I've seen here and other websites for this transmission has pretty much been to replace the n91 solenoid on top of the valve body. I called a mechanic buddy of mine tonight and though he hasn't dropped Euro valve bodies, he has done American and Asian transmissions. It's due its 60k fluid, gasket, and filter refresh, so I figured I'd have him replace this for me at the same time. If interested, the link I found for the n91 is Pressure Regulator 5HP19/FL/FLA - N91 Solenoid
 

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The common fix I've seen here and other websites for this transmission has pretty much been to replace the n91 solenoid on top of the valve body. ... If interested, the link I found for the n91 is Pressure Regulator 5HP19/FL/FLA - N91 Solenoid
I replaced the N91 on my 2004 B5.5 4Motion 1.8T 2 years ago to fix this problem and it worked great. Easy to do. Replace the filter and fluid while you're in there.

I had tried all of the other suggestions... Went to the dealer for a re-flash (but they couldn't even locate a flash update so I paid $100 for them to offer to replace the whole transmission for $thousands no thank you), Cleaned MAF, Drained and refilled ATF with Pentosin, Replace motor mount (snub mount), No improvement.

I wish I had just done the N91 first. I got mine from ECS Tuning along with the necessary ATF and replacement filter.

Did it on a lift. Never opened an Automatic Trans before in my life. Took about 2 hours because I was overly slow and cautious. On a scale of 1-10 this job was maybe a difficulty of 2 or 3... It was really easy (I used photos from a Russian site to find the N91 ... you need to drop the valve body which is easy, and its the only one on the top in the corner if I recall correctly).
 
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