[Watsey]

I'd appreciate input from the forum on this one.

I bought my 330d F31 it when it was 2yrs/25K miles old. It's now 8yrs/96K. XHP was flashed when the mileage was ~85K miles.

There have been a couple of annoying issues regarding the transmission ever since I bought the car - I took it to BMW several times but was always told that there's nothing unusual to investigate/fix :

The transmission 'hunts' between ratios 1-2 and 2-3, especially when the transmission is cold and/or when it's in Sport mode. This makes the car lurch forwards and backwards when I'm trying to drive smoothly.

When approaching a junction (almost to a stop) or briefly stopping at a junction, and then using a light throttle to accelerate again the transmission will often lose drive - engine revs can increase to as high as 1500rpm before there is a sudden jolt and the car moves forwards.

The transmission has had a fluid+filter (i.e. new pan) service at 50K miles (double drain + fill) and 85K miles (triple drain + fill) to make sure that the fluid is fresh and that the torque converter had been thoroughly flushed.

I called another ZF transmission specialist (most of them are only interested in doing a basic fluid+filter service) and they suggested having the TCU software updated and that it could be ~75% likely to fix the problem.

The developers of XHP firmly believes that it's a hardware problem.

Personally I suspect it's related to the mechatronic : sticky solenoid, a temperamental pressure sensor, or a checkball or spring valve sticking in one of the channels/seats.

Suggestions please...

[eugene89us]

That is certainly curious. Manufacturer of 8HP recommends (through its partner channels) to do maintenance on mechatronic unit. You would replace the solenoids, the little rubber dampers, and an intermediate plate inside the mechatronic. Fairly easy process and well documented online and in videos. There is a ZF technical document circulating that can provide step by step guidance. One place I would start is to pull up the adaptation values. They can tell you if there is a problem with one of the clutches or solenoids, at least something we can go off. I am sure last fluid fill was done properly, there is no chance of transmission being underfilled? ZF has roughness issues to it, especially when cold in lower gears, but once warmed up - smooth as butter. I would even say that when cold, the roughness is more of it trying to keep gear a little longer which make upshifts a little more sporty feeling when cold. Still a lot smoother than a warmed up DSG. Something here does not add up.

[Enabled]

What flash version was it on before Xhp and what version is it on now? I mean the swfl and its update versions.

[Watsey]

Originally Posted by eugene89us

That is certainly curious. Manufacturer of 8HP recommends (through its partner channels) to do maintenance on mechatronic unit. You would replace the solenoids, the little rubber dampers, and an intermediate plate inside the mechatronic. Fairly easy process and well documented online and in videos. There is a ZF technical document circulating that can provide step by step guidance. One place I would start is to pull up the adaptation values. They can tell you if there is a problem with one of the clutches or solenoids, at least something we can go off. I am sure last fluid fill was done properly, there is no chance of transmission being underfilled? ZF has roughness issues to it, especially when cold in lower gears, but once warmed up - smooth as butter. I would even say that when cold, the roughness is more of it trying to keep gear a little longer which make upshifts a little more sporty feeling when cold. Still a lot smoother than a warmed up DSG. Something here does not add up.

I certainly filled the fluid in accordance with ZF's instructions, including ensuring the transmission was in the correct temperature range.

Attached are snapshots from the XHP App which show the quickcharge times and the adaptation values. According to a reply from XHP Support (including a reference table - also attached) these values are all fine and indicate a healthy transmission.

I've watched several YouTube tutorials relating to servicing the mechatronic and that may well be my next move. Even the 'platinum' service agents recommended by ZF in the UK don't seem overly interested in further investigation in the absence of an error code showing in the diagnostics.

[eugene89us]

Those adaptations do look alright. As long as they are below 300 mbar, you're in the green. Mine are double digits, except clutch C at 168, which is still good and shifts well. So mechanicals appear decent, no sign of leakage or excess wear.

It sure would be curious to compare the version of your software to the ones we have that are trouble free. Do you have ESYS or ISTA to look those up?

But depending on the cost of Mechatronic rebuild kit, would be worth a try I would think. Simple enough as long as you take electrostatic precautions.

[Chihuahua]

Originally Posted by Watsey

Personally I suspect it's related to the mechatronic : sticky solenoid, a temperamental pressure sensor, or a checkball or spring valve sticking in one of the channels/seats.

Suggestions please...

This is what it sounds like to me too, you've hit all of your service intervals so you're good there. I had issues with my E60 (6HP19); intermittant erratic shifting, slip codes. Dealer told me I needed a new gearbox to the tune of $9000. I replaced solenoids, sealing sleeves, and Mecha connector seal and problems went away.

Are you getting any fault codes?

[Watsey]

Picking up on several of the points raised (thanks), plus some updates :

Using XHP to read the TCU, there are no fault codes recorded.

I don't have access to eSys or ISTA (I've never used these tools) - I don't know what BMW firmware is currently flashed as the 'base' map on the TCU.

I re-read the XHP release notes this evening and saw something that I hadn't noticed previously : cars built prior to June 2013 are requested not to run XHP Stage 3 V1.5. My car is a December 2012 build and I had already flashed this version release, not that I have noticed any difference (good or bad) in terms of the hunting & shunting (it was present for the 60K miles that I'd run the car with an OEM firmware TCU). Nevertheless, I've flashed the TCU to XHP's recommendation (V1.1) and will monitor for any changes.

I'm in contact with a ZF parts supplier in the US (Sonnax) - it's recommending that the mechatronic be serviced, its Zip Kit to be installed, the solenoids to be replaced, and the shift adaptations be reset. I've some further questions in terms of also replacing any relevant pressure sensors, check balls, the intermediate plate, and the like, so will continue the conversation to arrive at a sensible kit of parts for a thorough service of the mechatronic.

I've read several recommendations, including from XHP, NOT to reset the transmission adaptations as this can apparently increase clutch wear as the transmission re-learns the required tolerances necessary to avoid clutch slip. As I'm convinced that the hunting and shunting is a related to a sticking component I'll avoid resetting the adaptations at this stage.

I have found a knowledgable ZF transmission specialist who has recommended checking/updating the TCU firmware to BMW's latest version. Their experience is that this has ~75% success rate in resolving the issues that the transmission is experiencing, and at £80 it's a cheap first step in eliminating root causes before I embark on physical work on the mechatronic (and £hundreds in parts).

[eugene89us]

@Watsey Great plan, I think these should resolve the issues for sure. Take some great pics when you work on it, would be great addition to our overall knowledge if we learn together.

Wanted to consult with Enabled if there are specific TCU versions to avoid? I am not as familiar with ZF software as I am with engine control software. However, starting sometime in 2020, certain integration levels have incorporated new encryption protocols that preclude tuning and modification for the engine. Wanted to make sure nothing similar took place with TCU that will somehow affect your ability to tune it in the future.

[Enabled]

Originally Posted by eugene89us

@Watsey Great plan, I think these should resolve the issues for sure. Take some great pics when you work on it, would be great addition to our overall knowledge if we learn together.

Wanted to consult with Enabled if there are specific TCU versions to avoid? I am not as familiar with ZF software as I am with engine control software. However, starting sometime in 2020, certain integration levels have incorporated new encryption protocols that preclude tuning and modification for the engine. Wanted to make sure nothing similar took place with TCU that will somehow affect your ability to tune it in the future.

Nope, most of the older 8HP haven't had updates for a few years now. There is not hard encryption of the 8hp controller. However, there are still some on very early versions and I'm trying to see if there may be a trend going.

[DriveS]

Who did you use in the UK Watsey?

I just had my service done at Austrin and they seem to be very knowledgable about the ZF8.

[Watsey]

Originally Posted by DriveS

Who did you use in the UK Watsey?

I just had my service done at Austrin and they seem to be very knowledgable about the ZF8.

The first transmission fluid service was done by BMW in Stanstead (that may not mean much to people who aren't in the UK) and I did the the second one myself.

The transmission specialist that I spoke with recently is called Tadley Transmissions, based in Reading. Seemed very knowledgeable on the phone.

There's been a potentially interesting development...

I saw that there is a new version (update) of the XHP App. Downloaded it and was looking at the version release notes. I had already flashed Stage 3 version 1.5 but I noticed that it states that it shouldn't be flashed on cars which were built prior to June 2013. Mine is December 2012. There's no explanation of the differences between v1.1 and v1.5, nor anything regarding the differences to the cars/transmissions before/after June 2013.

I've flashed back to v1.1 and have driven the car pretty sedately for the first 200 miles or so and I've not noticed any hunting/shunting, nor any significant loss of drive when accelerating from a crawl. The shifts between the ratios seems a lot smoother too.

It may be linked to the refreshed adaptations process which follows each XHP flash, but obviously I'll be keeping a close eye on things.

Maybe it was software-related after all.

If anyone knows of any differences between the transmissions (8HP70), mechanical or the firmware, relating to the June 2013 build date threshold please do share.

[Watsey]

Originally Posted by DriveS

Who did you use in the UK Watsey?

I just had my service done at Austrin and they seem to be very knowledgable about the ZF8.

BTW, thanks for the suggestion re Austrin. They are too far away for me to visit, but I may call them for a chat / advice.

[DriveS]

Originally Posted by Watsey

BTW, thanks for the suggestion re Austrin. They are too far away for me to visit, but I may call them for a chat / advice.

They had a ZF8 in reception with half the cover off so you could see in and the guy was telling me how it worked and why it was so reliable.

Hope you get it sorted

[raki]

Any update? Have you managed to solve the issue?

[Watsey]

I had the transmission and torque converter completely stripped and rebuilt with a lot of new parts. That was in December 2021.

The shunting was fine for a few months but has started to return. I've no proof, but I'm starting to wonder whether it's related to running XHP.

[raki]

Oh ok. So are you back to square one, doest behave any better ? Do you mind me asking what sort of cost was it for that work?

[Eddamoo]

Originally Posted by Watsey

I had the transmission and torque converter completely stripped and rebuilt with a lot of new parts. That was in December 2021.

The shunting was fine for a few months but has started to return. I've no proof, but I'm starting to wonder whether it's related to running XHP.

Im pretty certain that Eco-Pro completely bypasses XHP - its a completely separate map that stays stock as it doesn't respect any settings the the idle behaviour is different. Did you try that to see if it behaves any better?

One frustration I have from XHP is that it never seems to 'de-clutch' the transmission at standstill, so I have to manually flip to N. Eco-pro is the only way to re-instate this.

[Watsey]

Originally Posted by Eddamoo

Im pretty certain that Eco-Pro completely bypasses XHP - its a completely separate map that stays stock as it doesn't respect any settings the the idle behaviour is different. Did you try that to see if it behaves any better?

One frustration I have from XHP is that it never seems to 'de-clutch' the transmission at standstill, so I have to manually flip to N. Eco-pro is the only way to re-instate this.

Eco-Pro. What's that ?

You're right about XHP not de-clutching the transmission at standstill. There is significant torque still being transmitted into the transmission. Like you, I always manually select N when stationary i.e. waiting at lights or in stationary traffic.

[Watsey]

Originally Posted by raki

Oh ok. So are you back to square one, doest behave any better ? Do you mind me asking what sort of cost was it for that work?

No, not back to square 1. It's not as bad as before, but it can still hunt under specific conditions.

It was a big bill, i.e. £ thousands.

[Eddamoo]

Originally Posted by Watsey

Eco-Pro. What's that ?

You're right about XHP not de-clutching the transmission at standstill. There is significant torque still being transmitted into the transmission. Like you, I always manually select N when stationary i.e. waiting at lights or in stationary traffic.

And as if by magic, i've just had a notification that a "Standstill Decoupling" setting has just been added to XHP! I look forward to re-flashing and trying it out!!

[Watsey]

Originally Posted by Eddamoo

And as if by magic, i've just had a notification that a "Standstill Decoupling" setting has just been added to XHP! I look forward to re-flashing and trying it out!!

Interesting !

My car is a 2012 build and for several years XHP advised that cars built before mid-2013 should not be flashed beyond v1.1.

This restriction was lifted a few months ago, so hopefully decoupling will also work for mine.

[Eddamoo]

Originally Posted by Watsey

Interesting !

My car is a 2012 build and for several years XHP advised that cars built before mid-2013 should not be flashed beyond v1.1.

This restriction was lifted a few months ago, so hopefully decoupling will also work for mine.

So i tried enabling it and..... it didnt work! Please do report back if you end up re-flashing yours!