09A tranny problems - this one's a little different

[rattlenbang]

This has happened twice now - 2004 jetta wagon 200k kilometers. When i put it into D or R from P, it bangs into gear, stalling the engine. Like a manual when you accidentally slip off the clutch pedal. Other than that the tranny shifts fine, no hesitation, no slippage. I know solenoids are touchy on these things, but usually they give upshift problems. Any ideas?

 

[j_martell]

Following this.

I had an identical problem about 3 weeks ago, the first "cold" day here all winter. Worked 10 hrs, started my car, waited the normal 90 or so seconds, pulled it into drive, and it thunked like I dumped the clutch on a manual.....fired it back up and all was fine. Still need to get it scanned to see if VCDS can pull a code from the TCM. Zero other problems since, and it's been just as cold or colder since then.

 

[gatz]

I'm not an expert but maybe the torque converter clutch lockup solenoid, N91. If its stuck in the locked position maybe. Just a guess on my part though. It's part of the set of 9 solenoids in replacement kit I put in my unit. Maybe more experienced folk can chime in.

http://www.volkspage.net/technik/ssp/ssp/SSP_232.pdf

 

[j_martell]

That's what I was figuring.....is there a way to see the status of N91 without VCDS, like an X-gauge on a ScanGauge II??

 

[rattlenbang]

I was wondering if it was something about the torque converter they way it felt like a sudden hard link from engine to wheels. And yet if it was locked up, surely that would have shown up on original shutdown? The notion that it locked up after it was parked doesn't make sense.

 

[j_martell]

Unless the lock up is held off hydraulically, and the pressure bled off and caused it to lock. But then it would have had to stick once started and pressure returned I guess? IDK

I suppose it would be more common also if this were the case. It's only happened to me once (owned the car since Sept 2014 with 268,XXXKM, now at 304,XXXKM) and you have had it happen twice

Just thinking out loud lol

 

[rattlenbang]

I just checked, and the solenoid has to be electrically operated to allow pressure to activate the torque converter clutch. The default is no no power, no clutch. A torque converter clutch sticking could cause this issue, but again, it's hard to see how this could happen while parking the car; at those speeds the clutch would be disengaged, and it would only be engaged again at high speeds. So what happens while it sits that it suddenly becomes engage? I suspect barking up wrong tree here.

 

[gatz]

According to the design manual the pressure must be positively turned on to cause the clutch to lock up. It also mentions that this vehicle engages neutral automatically at a stop but doesn't give much information about what solenoid state is needed to activate neutral.

These solenoids fail in one of two ways: electrically, so that when you put an ohm meter on they don't read what they should. The TCU (sometimes) reports this kind of fault on a scan with VCDS. And second: the solenoids stick. This is an intermittant type of fault, and it's what happened to me. I checked all my solenoids with an ohm meter and compared them to the new ones, they were the same value. I think fouled fluid or just age contributes to them sticking.

If you look at the rebuild kits, besides solenoids theres clutch packs, band brakes and two speed sensors. Those items require rebuilding to replace, solenoids are the only thing a DIY'er can really hope to try.

 

[gatz]

So what happens while it sits that it suddenly becomes engage? I suspect barking up wrong tree here.

Good point, although I'm at a loss of what else to suspect.

 

[gatz]

Oh speaking of, I had this video bookmarked from ages ago. For the curious

https://www.youtube.com/watch?v=3DprhBpYrZc

 

[j_martell]

Same. I was just thinking out loud and typing.....I will keep following this as others chime in because I'm curious the cause. More and more a manual swap is coming lol. Wifey will soon have her own car, so the Jetta need not be automatic anymore lol

 

[rattlenbang]

Good point, although I'm at a loss of what else to suspect.

Could be problem with torque converter; something internally jamming. Once the car is placed in gear, it's only torque converter slippage that keeps engine from stalling. Pressure accumulators keep it from banging into gear, but shouldn't be harsh enough to stall engine. I read through Gatz's tranny manual and when it describes various component failures, none mention drivetrain lockup. And while it does have a neutral disengage feature at idle, that's just for emissions and doesn't effect tranny operation if it fails.

 

[j_martell]

forgot about this thread....hasnt happend since, now at 331,XXXkm

still trying to decipher things i dont quite understand to get an x-gauge for monitoring lock up...its not going well lol