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Author Topic: DL501 Oscillation after shift  (Read 404 times)
ruan
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« on: November 06, 2019, 05:24:45 AM »

Yeah I know this forum is mostly about SI Audis with ME7, but I know a lot of guys on this forum work with these transmissions more than I do... I'm a Volvo/PSA guy really and don't have all the tools to pull the file off a CP14 with tprot.

I've just picked up a B8/8K A4 Allroad with the CCWA 3.0TDi 239 and 0B5 DL501 S-Tronic, it's got a file from Superchips on it which I've logged with what tools I have (not VCDS sadly), but it appears to be reporting a peak of 620N.m Engine Torque which from brief looking at a file from a CCWA, 620N.m is the same value at peak as in EngPrt_trqLimP_MAP, so guessing fudged torque conversion. I've seen a peak of 82mg/str, which is significantly higher than in PhyMod_trq2qBas_MAP.

It's got the classic DL501 fault of banging harshly into 1st gear when rolling slowly to a stop and then hitting the gas to accelerate again, but another weird fault is that it seems to oscillate on some shifts. I've managed to catch a video of it doing it when it's pretty noticeable under high power, it seems that the engine speed isn't quite correct, it slips the clutch a little and the TCU performs a torque intervention due to it seeing the slip. It also does it on lower power shifts, it seems that the engine speed isn't quite right at the point of the alternate clutch engaging, hence the engine speed jumping up/down and setting up an oscillation.

https://www.youtube.com/watch?v=y81MM5_E3ms

Has anyone with more experience with these transmissions seen this before, is this likely a fault or just due to bad tuning? If it's likely due to the shit map sending de-calibrated torque values to the TCU, I'll pull down an original and flash it back to stock, I do tuning as a hobby really and I've not invested in a tool that can do MEDC17 BSL to pull what's on there as of yet. If it requires re-tuning, I'll go from scratch and do it again and proabably invest in the tools to flash these ECUs and the DL501 itself.
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prj
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« Reply #1 on: November 06, 2019, 06:54:08 AM »

You can NOT decalibrate torque on any dual clutch transmission and expect it to work. This is 100% the reason for clutch slip.
2->1 banging = mecha unit, replace and will be fixed.

PCMFlash is the cheapest tool for you to do both the DL501 and the ECU over OBD.
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ruan
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« Reply #2 on: November 06, 2019, 07:13:50 AM »

You can NOT decalibrate torque on any dual clutch transmission and expect it to work. This is 100% the reason for clutch slip.
2->1 banging = mecha unit, replace and will be fixed.

PCMFlash is the cheapest tool for you to do both the DL501 and the ECU over OBD.

Exactly as expected, thanks, I'll ask favours to see if someone can pull the original so I can see what previous owner paid for. Pretty set on PCMFlash, although I'm not 100% on whether it can flash CP14 via OBD with tprot on?

What's the _ACTUAL_ cause of the 2->1 banging which is fixed by replacing the mechatronic unit?! I'd heard it's due to adaptation of the clutch pressure from previous microslipping causing it to not release K2 enough before beginning to engage K1 - but I don't actually know.

https://www.youtube.com/watch?v=DFgUuL4yrT0

This is what I mean by the slight oscillation even at lower power, after the shift is performed, the engine speed takes a while to settle, you feel this as the driver as a "bouncing" or "oscillating" sensation as the power comes back in.
« Last Edit: November 06, 2019, 08:56:21 AM by ruan » Logged
cherry
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« Reply #3 on: November 06, 2019, 10:59:01 AM »

There is a repair set available from Audi with 2 clutch valves and a cooling valve included, no need to buy complete mechatronic. Then you need to flash latest software and calibrate valves, this is other procedure than basic setting clutches. If you do not have dealer diagnostic better ask dealer to do the job. After this normal basic setting and adaption drive is done. If your clutch is already burned you need to renew them too...
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ruan
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« Reply #4 on: November 06, 2019, 11:20:03 AM »

There is a repair set available from Audi with 2 clutch valves and a cooling valve included, no need to buy complete mechatronic. Then you need to flash latest software and calibrate valves, this is other procedure than basic setting clutches. If you do not have dealer diagnostic better ask dealer to do the job. After this normal basic setting and adaption drive is done. If your clutch is already burned you need to renew them too...

Pretty sure the TCU is on the latest software - P/N 8K0927156J Software Version 0014. At last check, there were no faults registered in the ECU/TCU

So it's the clutch valves and/or thermostat valves that actually fail and stick, causing the problematic clutch actuation? I'll have a search for the repair kit - I've seen the "DL501 Repair Kits" which seem to just be the flex board and wiring harness without any valves. I suspect VCDS will be my next purchase.
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k0mpresd
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« Reply #5 on: November 06, 2019, 11:26:41 AM »

although I'm not 100% on whether it can flash CP14 via OBD with tprot on?

pcmflash can flash any vag medc17 via obd without issue.
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cherry
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« Reply #6 on: November 06, 2019, 11:36:56 AM »

Repair kit should be P/N 0B5398048D. But ask your dealer, some early mechatronics are different and no valves available from dealer. I dont think you can make all adaptions with VCDS because it´s not documented. If you just change valves and think problem is fixed you can kill even more. Maybe clutch is already burned thru failed valves are stupid software.
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ruan
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« Reply #7 on: November 06, 2019, 11:59:08 AM »

Repair kit should be P/N 0B5398048D. But ask your dealer, some early mechatronics are different and no valves available from dealer. I dont think you can make all adaptions with VCDS because it´s not documented. If you just change valves and think problem is fixed you can kill even more. Maybe clutch is already burned thru failed valves are stupid software.

Urgh. Nice.

Well, I've checked codes with a relatively modern tool, coming back with P174000 intermittent, which is Clutch Temperature Monitoring. Suspect clutches slipping causing it combined with thermostat valve issues. It's under warranty, so it'll be going back, if it were me I'd be looking at clutch pack and mechatronic repair + valve replacement.

 
pcmflash can flash any vag medc17 via obd without issue.

Great news, thanks.
« Last Edit: November 06, 2019, 12:01:14 PM by ruan » Logged
prj
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« Reply #8 on: November 06, 2019, 02:32:43 PM »

The repair kit does not help for 2->1 banging issue AFAIK.
I've always replaced the mechatronic unit, and that solved. The dealer also does NOT recommend a repair kit for this specific issue, they replace the mechatronic on a hard 2->1 bang.

But who knows, repair kit might work, it's certainly cheaper.

Thermostat valve with coolant leaking and entering plug is a totally different story and will make entire car go dark if it shorts the CAN out.
Change it before this happens.
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cherry
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« Reply #9 on: November 06, 2019, 04:00:35 PM »

Btw i´m talking about the valve for clutch oil cooling which let the clutch burn when it fails. After installing the repair kit AND correct basic setting from the valves (not normal basic setting!) these cars drive smooth again. It´s a little bit hidden in Odis and not in normal functions, there is also a TPI for it.
The water cooling valve is a very bad thing and can cause high damage. Also water containers in some MQB cars make problems again in the moment. A trick is also to cut the wires and solder them together again, this will stop water. It was a common trick for some older Opel cars with leaking camshaft actuator valves, even after replace them...
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prj
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« Reply #10 on: November 07, 2019, 09:13:11 AM »

I am talking about specific 2->1 hard shifting issue without any other issues present. Every gear working perfectly, only 2->1 giving hard shift when coming to a stop. This has nothing to do with cooling valve.
In both cases that I experienced it on low mileage vehicles (under 100 000km), the Mechatronic replacement solved the problem and nothing else was changed in the transmission.
Both cars drive fine.

Maybe replacing the solenoids would help, idk.
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ruan
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« Reply #11 on: November 08, 2019, 04:13:45 AM »

I am talking about specific 2->1 hard shifting issue without any other issues present. Every gear working perfectly, only 2->1 giving hard shift when coming to a stop. This has nothing to do with cooling valve.
In both cases that I experienced it on low mileage vehicles (under 100 000km), the Mechatronic replacement solved the problem and nothing else was changed in the transmission.
Both cars drive fine.

Maybe replacing the solenoids would help, idk.

Thanks all for suggestions, it's now in the hands of warranty idiots. I'll be pushing for a full mechatronic unit replacement, but I suspect they'll want to try the repair kit first. I'll keep updated with the situation as I'm interested to know what causes this.

Upon further reading, I'm slightly convinced that the 2->1 "banging" is different to what I'm experiencing, whilst mine does "jolt", it feels more like a clutch actuation problem rather than a "bang" - as it engages K1, it actuates the clutches far too rapidly and the revs suddenly dip and you feel the car jump, I've even had it stall the engine before now as K1 engages which is what I refer to as the "bang" as it feels like the engine's about to fall off the mounts. It seems almost like the solenoid jams or similar, it winds up and then suddenly applies pressure to the clutches as the solenoid unjams from greater current being applied. It pretty much ONLY does this when cold FYI and it's done a little over 162,000KM, the colder the components due to the ambient temperature, the worse it can be, it doesn't "jump" in other gears, but other shifts when cold are not particularly smooth, there's lots of delay, however, I've never driven anything with a DL501 which I know does not have this problem to compare to.
« Last Edit: November 08, 2019, 04:15:53 AM by ruan » Logged
prj
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« Reply #12 on: November 08, 2019, 06:36:55 AM »

What you are describing is precisely what is solved by the mechatronic replacement.

Warranty - Audi will deny any factory warranty, since your car will be TD1 when warranty check is done, as the ECU is not stock.

If you bought the car from a dealer with this already present then you are of course entitled to a statutory warranty, and this should not matter.

The dealer procedure for this matter is to replace the mechatronic unit, the repair kit is for other issues.
« Last Edit: November 08, 2019, 06:39:22 AM by prj » Logged
ruan
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« Reply #13 on: November 08, 2019, 06:46:28 AM »

What you are describing is precisely what is solved by the mechatronic replacement.

Warranty - Audi will deny any factory warranty, since your car will be TD1 when warranty check is done, as the ECU is not stock.

If you bought the car from a dealer with this already present then you are of course entitled to a statutory warranty, and this should not matter.

The dealer procedure for this matter is to replace the mechatronic unit, the repair kit is for other issues.

Of course, yes, the car was from a non-VAG dealer, the car was supplied with the tune on, so should be zero TD1 issues.

I'll push for the mechatronic replacement - do you know if there's a TSB for this issue?

Thanks for help so far.
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