project 2009 Z4 E89

[SiC]

22 minutes ago, SiC said:

that chime that all BMW owners fear

This is too accurate (thankfully I don't have a N54 - that's the 3.5 twin turbo)

https://www.instagram.com/reel/C6HSgxXPH4t/?igsh=MXhuN2w0cmlmdHk3cA%3D%3D

 

[Split_Pin]

I can't find it now but there was a reel with some lad recreating the bong on his xylophone. 

I'll probably be flinching on the plane to Turkey next week when every announcement opens over the intercom - bing bong, you need Tech 2!

[SiC]

Ah yes I remember that Saab bong all too well - my 9-3 liked to tell me it was broken regularly!

[SiC]

Stuck it on charge again this morning. Gave it a quick start to see what the state of play currently is.

PAS deader than a dead thing.

No noises, no comms, no assistance. 

Looks like its died completely now. Sad times.

I'm going to check the earths and fuses (when I figure which one it is) but I suspect it might be the combined motor/control at fault. Mostly as when it did work and have the warning on the dash, the wheel still had a fair bit of assistance. I'd expect dry steering to use the most power and show up any power supply issues as not providing full assistance.

The motor is on the bottom of the car. Not the hardest to get to. Removing it is a bit of faff but something I should be able to do. Just need to decide whether to buy a second hand rack+motor or send this off to repair. I need to double check power supply lines first and then decide. 

[SiC]

Just come back from a short holiday in Tenerife. Weather was lovely and not too hot - unlike apparently the UK has been recently.

 

So back to this irritating car. I hate cars. I was hoping to be getting on with the Midget the next few days, not fixing the Z4.

Just been on to the phone to BMW Bristol and ordered a set of alternator bolts. Being TTY aluminium bolts they're only one use. £11 for a set of four. Cheaper than the £22 odd off eBay but still annoying they need to be replaced just to take off an alternator.

The box of bits that need fitting to fix is growing. 😅😭

Last night I had a bit of time to jack it up and have a poke around at the steering rack warning light being on. Only code I have is the instrument cluster saying no comms to the rack.

The EPS assistance actually works fine. It's not heavy steering at all. However it pings up the warning light all the time when driving. Also the assistance is supposed to be speed sensitive - at high speeds it reduces assistance from reading the speed over the car CAN network. Hence it's a bit unnerving on the motorway with the steering wheel pretty lightly weighted as it's in a fault state giving maximum assistance. So I could ignore it but the binging/binging is very annoying and the assistance is not pleasant to drive.

The motor and rack is actually quite accessible as it's situated right on the bottom of the car. 

Jacking it up was a bit tricky as the thing is so stiff that it's got one wheel in the air when using only one stand.

So I ended up just jacking the whole front end up instead.

Three connectors on the rack motor. This contains the control unit too and so the car CAN powertrain network is connected to it. 

First off I checked the chunky power connector. Test light showed a healthy brightness and the negative to earth on a multimeter showed extremely low resistance. This would suggest power to the unit is okay. I think this makes sense as the fault I'm seeing is that the rack power assistance actually still works, just the rest of the car can't talk to it.

Next up was the other two connectors. Bottom (disconnected in this pic) is to the torque sensor on the top of the rack. Top is the CAN network connection.

The torque sensor connection I think is fine. I disconnected it and the rack stopped providing assistance. This makes sense as it can't sense where the demanded position is from no sensor. It also was a useful test as there still was no comms to the rack. Given the assistance was completely off, the power consumption was minimal and thus any dodgy power connection shouldn't be enough to both cause the module to not work properly and light up the test light.

 

I found this diagram on a E90 forum that described the pinout of the CAN connection. Only three wires.

15WUP is the wake-up signal. Simply putting power on here will cause the unit to wake up and start communicating. Basically ignition on feed. I was getting 11.5v on this line. Which given the battery is a bit flat, absolutely about right.

CAN is a 5v differential signal. What this means is that there are two data lines. One switches from 5v to 2.5v and the other from 0v to 2.5v. This is by design as it cancels out any electrical interference. 

CAN-H line was reading 2.58v. 

CAN-L was reading 2.37v

As there was likely traffic going across the network, it'll be averaged voltages. So those values seem absolutely bob on what I'd expect.

I probably should stick the oscilloscope on those lines to make sure things look sensible in more detail, but I'm pretty happy there is no wiring issue. The wiring is bent quite sharply over and would usually be a red flag but I gave the wiring a wiggle and those values didn't change.

So this leaves an internal fault in the EPS motor control unit as the highest probability. Boooo

New/refurb racks are £LOL (over a grand), so that's not happening.

ECU Testing will fix the motor unit for £500. Probably the least hassle course of action.

Second hand racks range from £150 to £350+. Probably the best course of action for a garage as just a case of slapping a rack on and push it out the door. Get the right/same part code and it'll probably not need coding for the car to be happy. For me, fitting a rack on my back on the drive doesn't sound like a whole lot of fun. While accessible, still a massive faff and a realignment will likely be needed.

I could probably take the motor off the second hand rack and fit it. But a quick look on eBay found the BMW motors available second hand. Unfortunately nothing for a E89 but there were some for the E90/E87/E83 (3'er/1'er/X3 iirc). 

Would they work?

A bit of googling found this post.

https://www.e90post.com/forums/showthread.php?t=1729509

Invaluable nugget of info. Basically three revisions of the motor - E90/E87/E83, E89 (2009) and then a later with all three (2010+). Checking NCSDummy (BMW coding application) showed that the later revision had E89 variant coding options. Makes sense as BMW do like to reuse parts to save costs. You can't get the wrong type and reflash it to a later unfortunately. However in theory I could get a later motor and fit it. RealOEM only show one part number for the E89 rack (remanufactured unit), so a later unit should work fine on my 2009 car hopefully.

But how do I find the right part?

This was the motor I was after buying.

After a bit of hunting on eBay for used E89 racks and looking at motor part numbers, I found this for sale which had that identical part number on it.

Fantastic! 

This means the £34 motor above should hopefully be retrofittable to my rack 🤞

I'll need to do some coding but hopefully it will just be a case of telling it that it's now in a E89 Z4 and it'll play nicely with the rest of the car 🤞🤞

 

If this works then it's a £150 to £1k+ cost saving on other repair options!

Now after writing all that and procrastinating, it's time for me to go back outside and start fitting this window regulator.... Tomorrow will be the fun* of the DISA valve. Maybe replacing the rack motor too if that arrives (I suspect that'll be next week though).

Kids, just don't do drugs old BMWs

[scdan4]

If that motor does work then that's an great win. Top sleuthing 😁

[Split_Pin]

Aye top work, my patience would have run out with jacking it up 😂

[N Dentressangle]

what a PITA

I really hate modern cars. No-one asked for computer-controlled speed-sensitive electric power steering. Just yet more pointless and expensive shit to go wrong, innit?

[SiC]

Wasn't too tricky to get to this stage of glass out. Helped that I had the replacement regulator next to me in finding fixings.

All in a few hours job. Time consuming rather than hard. 

Oh wait, what is that gap at the top?

Oh FFS! The glass isn't high enough. Tried reinitalising the window position with a scantool but still too low.

Time to disassemble the door again...

BBL 🥲

[N Dentressangle]

'reinitalising the window position'

Who comes up with this crap? 🤣

[SiC]

I'm currently sat in the passengers seat staring at the door thinking to myself "I really don't want to pull that apart again". But know that I need to if I don't want it filling full of water. 

I am so glad I don't have to do this as a paid job. 🙃

[SiC]

8 minutes ago, N Dentressangle said:

'reinitalising the window position'

Who comes up with this crap? 🤣

Once I get it all sorted, I'll do a video of the roof in operation. About as remarkable in operation as my wife's facial expression when she was watching it opening. 

It's pretty phenomenal any of these cars still work at 15 years old. I imagine by the time they're 40+ year old classics, owners will be too scared to touch the roof button and just store them always open in a garage. 

[Split_Pin]

I recall the regulator on my A4 cabriolet being a bloodied-knuckle war. 

Good luck!

[mk2_craig]

I still have PTSD from dismantling the Bini R57 drivers side window mechanism FOUR FUCKING TIMES.  Looks like the adjustment methods etc is probably similar on this, you have my deep sympathies. 

[SiC]

Just tried out the roof. Opened fine.

Closed .... well we've stopped here for no apparent reason. 🙈🫠🤣😭 Is about my emotions right now.

[Wibble]

1 minute ago, SiC said:

Just tried out the roof. Opened fine.

Closed .... well we've stopped here for no apparent reason. 🙈🫠🤣😭 Is about my emotions right now.

You clearly have far more patience than I do. I’d be dropping a match down the filler neck right about now.

[SiC]

Okay it wanted the drivers door shut to continue. No idea why and it wasn't telling me that. 

Battery is also quite low from faffing with the windows which is probably not helping. I do have it on charge but that likely won't be meaty enough to supply the whole car with it on. 

I'd remove the battery and charge it off the car, but if you close the boot with no battery, you can't get access to it again as it's electric release. Makes sense to do that on a thing that hides the battery away. Well I imagine there is an emergency handle somewhere but I can't find it and Google isn't helping me find anything. 

[N Dentressangle]

1 hour ago, SiC said:

Once I get it all sorted, I'll do a video of the roof in operation. About as remarkable in operation as my wife's facial expression when she was watching it opening. 

It's pretty phenomenal any of these cars still work at 15 years old. I imagine by the time they're 40+ year old classics, owners will be too scared to touch the roof button and just store them always open in a garage. 

None of them will become 40 year old classics. Not because they're bad cars - they're quite the opposite - but because the numerous, mostly electrical faults will make them impossible or unviable to repair.

The L322 Range Rover and Discovery 3 are cases in point. They're worth little more than scrap value if they're broken, and not that much more when they're working. Because everyone knows the next error message or £1k+ FTP is just around the corner. Whether it's a broken crank, knackered autobox, electronic module failure, electronic handbrake failure or some other crap, they're unviable to mend. There will be very few left in 10yrs time.

Your ability to fix electronics in particular is way higher than the average guy. Far higher than mine, certainly. If you were paying someone £60ph+ to do the work, like 99% of people would have to, the car quickly becomes scrap.

[SiC]

15 different sensors to detect which part of the roof is where on this. No wonder this got stuck yesterday. I won't deny, this roof gives me the fear a bit. Not that I won't know how to fix it, more that if it fails when out, there isn't an easy way of overriding it to close. If the soft top module isn't happy that one of those 15 sensors or 8 motors/valves aren't working correctly, it'll stop exactly at the point it was unhappy and won't move again till it is. 

The only manual override is a hex bolt on the hydraulic pump that you can undo to release pressure. Then manhandle the roof panels into some sort of correct position. Finally hope that it's close enough to close that it'll lock the roof so you can drive off home. 

Except that release screw is in the boot and you can't get into the boot manually as it's a fully electronic (soft close) release mechanism with no override handle. Also the boot is inaccessible from the passenger compartment on EU models (USA had a ski hatch), so you can't even get to the mechanism. 🫠

The cause of this stoppage appears to be a hall effect sensor (think of a micro switch that's triggered by a magnet).

No wonder there is a breakdown recovery phone number scrawled on the back of the owners manual. 🤣

 

I've managed to find on the internet the factory service manual for a 2014 USDM model. Hopefully enough similarities that it'll provide some learning material on how it all works. 

A Diagnose Dan gives an idea on what's in store if a sensor malfunctions. Plot spoiler, it was a broken wire in the loom. I know this happens quite often on these as the wires are attached to the mechanism with many pivot points to work harden/snap wiring.

 

It really makes me appreciate the simplicity and comparative reliability of my old E85 roof - which even then has a reputation of issues. 

[SiC]

Window now works lovely. I basically removed the door card again, undid the glass clamps and pushed the glass up as high as it could go. Then moved it down to match the dirty glass line you get from the seals to match how it was before. 

Looking at the old mechanism, there really wasn't much life left in it. I imagine the drivers side window might need similar attention at some point given these get operated together when opening the top.

[SiC]

Started on the DISA valve replacement last night.

Air box out. 

Throttle body and large DISA removed.

Three bolts this side attach the small DISA which is on the other side of this. Pic is to remind me the long bolt is at the bottom. 

Old versus new.

Belt off. Pic to remind me of the belt path. Simpler than my 330i as no PAS hydraulic pump and idler pulley.

Alternator out.

Disconnected the vacuum pump line - a bit more difficult than I expected as it still had vacuum in it). Hands in deep to remove the DISA while being ever so careful to not snap any of the plastic CCV hoses. I did detach one of them to give me a bit extra room to manoeuvre it out.

DISA is the black thing in the middle just below the manifold tubes and the ccv disconnected pipe on the left.

Both old valves out. 

Replaced the tensioner and belt while I was there. You can see how the belt was riding on the edge. Not as bad as my 330i but well worth replacing.

Bolt is aluminium and TTY (Torque To Yield) so one use. 25NM and then 90 degree turn on its replacement.

Likewise these alternator bolts (four of them) as TTY one use only too. Fun 😒

I buttoned it all back up until BMW Bristol let me know my order has arrived. Bolts in are torqued to only 10NM, so hopefully will easily remove without snapping. Replacements will be 10NM + 180 degrees. 

 

Smashed open the old valves to see what their value mode was. They are bonded together so not realistically repairable. 

Small DISA was a mix of disintegrated motor bush, oily+watery mess that rusted most of the internals and components falling off the control PCB. No wonder this was throwing error codes.

Large DISA wasn't as bad in comparison but still a disaster. This one wasn't throwing codes (probably because the control PCB was okay) but given the rusty mess, it's not a surprise that it had failed too. 

Looking inside these makes me wonder what state my 330i valves are in. No codes but they're older (older revisions too), slightly more miles and I bet they have never been replaced.

 

Hopefully I can get those bolts today to finish button it up and go for a test drive. Fingers crossed it will feel more spritely (especially low down) than before. 

Royal Fail are supposed to be delivering the PAS motor today too. 

[Kiltox]

32 minutes ago, SiC said:

Window now works lovely. I basically removed the door card again, undid the glass clamps and pushed the glass up as high as it could go. Then moved it down to match the dirty glass line you get from the seals to match how it was before. 

Looking at the old mechanism, there really wasn't much life left in it. I imagine the drivers side window might need similar attention at some point given these get operated together when opening the top.

That’s definitely used! 😳

[SiC]

All this talk of DISA valves, here is an explanation of what they are and what they do that I found on a BMW forum.  The older M54 (as in my old Z4 E85) only had one DISA valve. This has two for optimising the intake tract length for varying revs. 

 

 

This is why I'm hoping for a more sprightly engine now they should be opening correctly when they are being expected to. 

[Jenson Velcro]

Top skills in diagnosing, then fixing the problems and particular thanks for detailing and explaining the processes so an ignorant numptie like me has half an idea what’s going on.
I was doing some mental arithmetic trying to guess what this would have cost if undertaken by a garage (even if they have the skills for such) and it’s no wonder cars of this age will fall into disrepair and get scrapped.

[Split_Pin]

You don't hang about! Nice work all round as always and detailed write up. My eyes and brain went a bit Father Dougal when reading the explanation on Disa valves though!

[SiC]

44 minutes ago, Jenson Velcro said:

Top skills in diagnosing, then fixing the problems and particular thanks for detailing and explaining the processes so an ignorant numptie like me has half an idea what’s going on.
I was doing some mental arithmetic trying to guess what this would have cost if undertaken by a garage (even if they have the skills for such) and it’s no wonder cars of this age will fall into disrepair and get scrapped.

I'm not out of the woods yet with the EPS 😬

There are two things I am hoping will pan out true with the motor I receive. Firstly it's the right model code that has E89 programming. If not then I'll probably have to fork out for a second hand rack or send my motor off for repair. Secondly that when I plug it in, the car CAN network will see it. If not then I've got to dig into the wiring more as it would likely be a wiring fault (or a faulty used module). 

Prices?

EPS main dealer/specialist probably would put an entire new/reman rack on. Autodoc list a reman for £1k and new £2.5k. Both out of stock but probably realistic on dealer prices. Then labour - probably a good 3 to 4 hours at £150p/h (I think that's the going main dealer rate now) including diagnostic coding. So you're probably looking at the thick end of a £2k to £3k bill. 

Window main dealer I saw a BMW dealer selling brand new regulator on eBay for £160. Again another 3 hours or so labour, you're looking at a £600 to £800 bill. 

DISA valves are a tough one. Unlikely anyone would even know they needed replacing. I mean I wouldn't have done unless I saw the code. The only way someone would have suspected something is up if they drove back to back with another and felt it down on power. But that can be subjective. It's also why I'm going to check my DISA valves on my 330i as I wonder if I'm missing something on them. Not only do they help performance, they also help fuel economy. As that regularly does 20-25mpg, anything to improve it will be appreciated! 😅

Anyway with the window and rack at a main dealer, you'd be looking at nearly the purchase price of the vehicle...

Independents I'd hope would Google for rack faults and see ECU Testing would do a repair for £500. Add a few hours labour and additive for faff, probably £1k? Window regulator probably half the cost of a dealer/specialist? So probably £1.5k all in to fix.

 

The second hand window regulator cost me £16 posted and if this used motor actually works that was £34 posted. So £50 all in to fix those two faults all being well 🤞🤞🤞🤞

Plus my time of course.

DISA valves were £300 all in but I see that as the icing/decoration on the top of the cake. A garage would be a good 5-8hrs in to do it as the recommended way is to remove the Inlet Manifold which is a big job. Also the starter motor is then accessible and I'd imagine them recommending possibly to replace that while they are there. 

[SiC]

43 minutes ago, Split_Pin said:

You don't hang about! Nice work all round as always and detailed write up. 

I've got to be! Owning two old BMWs is like painting the Forth Road Bridge. Once I've fixed one and got it back on the road, there is a good chance the other will be broken again and need fixing! 🤣

[SiC]

1 hour ago, Split_Pin said:

My eyes and brain went a bit Father Dougal when reading the explanation on Disa valves though!

I'm not an expert in thermo and fluid dynamics by any means. However my take on it is as follows.

Imagine water rippling in a bath. When that water hits the side, it bounces off creating a wave/ripple. If that wave hits a wave at it's peak, it'll double the height. If it hits a wave at it's minimum, it'll cancel out. 

The idea of the variable intake is similar if you imagine the air as a liquid that you could see. 

As the air is flowing into the piston with the valve open, it has momentum moving it in. When that valve stops, the air doesn't suddenly stop moving - it still is trying to rush into the cylinder as it has momentum in those particles. However it has nowhere to go. Thus it bounces off the closed valve - like water hitting the side of the bath. 

The article above also mentions the moving piston creates waves back too when the valve is open. Presumably this is from the air swirling around in the piston and also air bouncing off the piston. So that also is an effect of the waves in the air in the intake manifold too. 

Likewise as that air is travelling back into the manifold, it will bounce off the sides - like bath water waves would hit the opposite side of the bath and travel back again. 

So by combining these two events, you can 'tune' the air waves to be at a positive pressure (pressure peak) or negative pressure (pressure hole) at the right time. With a fixed inlet manifold, you can only have a fixed effect on those waves at certain frequencies to have the best effect. Multiple revs speeds on a fixed will be effective as there is harmonic frequencies - don't need to understand the big details on that, just multiple revs will be effected (just to lesser/greater degrees). By making it a variable intake, it allows the engine computer to optimise the best intake profile depending on the revs. 

So you can see that these valves need to open/close quickly (especially as this is a quick revving engine) and at the exact right time to make the system effective. Them doing this when they should be snapping open/close is not going to crack it.

The above is all my understanding from that text and intake manifold theory from what I've read previously. If there are any experts in the field of thermo/fluid dynamics please pipe up and correct any mistakes or incorrect assumptions!

Either way it's all very clever stuff. Things you'd expect on a race or even an F1 engine. Not your every day shopping/posing car. 

[mk2_craig]

2 hours ago, SiC said:

the drivers side window might need similar attention at some point

It may well already have been replaced at least once! 

[Kiltox]

A friend had a steering issue with an older Z4 and it cost similar eye watering money to replace the rack 🫣 so I’m definitely hoping your cheap fix sorts it.