project 2009 Z4 E89 - normal operation and 🤞long that it may continue

[Supernaut]

On 26/06/2025 at 13:03, SiC said:

Kids, just don't do drugs BMWs from any time after the 1990s

I love my E36 but I'm absolutely NOT going to ever buy a newer BMW.

The E36 is relatively simple, just a boggo 1990s car, really.

[bigfella2]

Forget about getting a rack from Autodoc they won't send anything bulky, just tried ordering a bumper grill for my megane and was politely told to fuck off.

[SiC]

Got me bolts. 

1hr45 roundtrip as I forgot about M5 Friday afternoon/evening craziness. I probably should have picked them up tomorrow morning. Oh well. 

Check out the colour of this brand new M135i. Fair play not only to the owner for specing it but also BMW offering it as a colour option. Not to my taste but I absolutely love the brightness of it.

If you blocked off the BMW badge, I'd swear it was a Ford Focus.

[N Dentressangle]

I can't tell what most modern stuff is unless I can see the badge either.

[SiC]

Used module isn't talking either. 😐

Not sure if another dead module or wiring issue still. 

Annoyingly global parts didn't send the same part code that was on the listing.

 

[beko1987]

Grounds for a refund at least as the part you ordered wasn't the specific part pictured? 

[SiC]

Not going well

CAN Signal look absolutely fine to me at this end of the connection. Only thing I probably should do is back probe it when the module is connected.

 

 

[SiC]

Wake up signal is simple. Goes to 12v when ignition on. Goes to 0v when ignition off.

 

[SiC]

Plugged the new module in completely just in case it needs the torque sensor in to communicate. No difference. Scan tool can't connect to it either.

I'm stumped 🫤 

CAN connections look fine. Wake-up line is fine. 

Ground seems fine. Power I think is okay but possibly should double check. 

Only thing left really is to back probe the CAN lines with it all plugged in. 

[SiC]

33 minutes ago, beko1987 said:

Grounds for a refund at least as the part you ordered wasn't the specific part pictured? 

Yeah it's something I'm considering. It's on the edge of being too old to not support E89 anyway. 

[SiC]

Just been out on a test drive. 

Good news is that there is heaps more low down torque. Up the steep hill near me it was still pulling from 30mph to 50mph in 5th gear. Still doesn't feel a super quick car but then it's 'only' 200bhp and my perception of what is fast is likely a bit warped nowadays.

Bad news is that the PAS light is still on. It's definitely providing assistance but it varies. Sometimes it goes light, sometimes it twitchy and sometimes it goes heavy. My suspicion is that if it can't see the steering angle sensor, it's making do with the torque sensor but it can't fully be smooth with just thay. I also get the steering failure warning bong occasionally when driving. This suggests it does talk briefly on the car network and then falls back off again. 

I'm 99% sure still that the module is at fault. A Facebook post I put on the E89 group basically say all the problems I'm seeing are because the module is faulty. The recommendation seems to be to take the motor unit off and cough up £500 to send to ECU Testing. 

I need to find the ground connection to body to fully rule that out. 

I'd like to trace the power wire but it goes from back to front in looms. But given the thickness, it would be extremely unlikely for it to have broken internally. Only if there are some joins along the way that could have caused issue. I need to do some research on the wiring. However from the brief amount I've done, I think it's a solid cable from back to front. 

The rear power connection goes into a join box. This I don't think has fuses in, just one main central fuse on the battery from what I can tell. Either way, this all looks clean and perfect condition. The blue wire is definitely the EPS motor connection as it drops to zero volts on the motor end when disconnected.

[vaughant]

Sorry it's not working out for you 😢😢😢, I've been there many times before with daft faults and often it's like you say, specialist only 🙄🙄🙄.

These are probably slightly too modern to start bypassing things but for what it's worth I think you're doing sterling work on it that very few others would undertake 🫡🫡🫡🫡.

 

Keep up the good fight soldier 🪖 🪖 🪖.

 

[vaughant]

Not easy I know but could you get a clamp meter or multimeter inline and set it to min/max then go out and try it again? Just to get a bit more of a feel for what conditions cause it on the run?

[New POD]

On 26/06/2025 at 15:41, N Dentressangle said:

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?

In 1992, the bloke I sat near next to at the offices in the Lucas Research Centre in Shirley was assigned part time to an electric power steering project at Lucas Car Braking in Fen End.  

I think that's what most of the car manufacturers told them when they invited them to discuss thier prototype.  

30 plus years later the Lucas Automotive plant in Halford Drive that used to make Alternators makes electric Power Steering under the TRW brand name.  

[cort16]

Are the modules VIN coded  or is it old enough to avoid this?  I know in some instances if this is the case they still work in a fashion but throw up errors and can't be calibrated.

Good luck with it,  it reminds me why I now have a self imposed BMW ban!

[High Jetter]

4 hours ago, New POD said:

In 1992, the bloke I sat near next to at the offices in the Lucas Research Centre in Shirley was assigned part time to an electric power steering project at Lucas Car Braking in Fen End.  

I think that's what most of the car manufacturers told them when they invited them to discuss thier prototype.  

30 plus years later the Lucas Automotive plant in Halford Drive that used to make Alternators makes electric Power Steering under the TRW brand name.  

TWR is Tom Walkinshaw?

[New POD]

4 hours ago, High Jetter said:

TWR is Tom Walkinshaw?

https://en.wikipedia.org/wiki/TRW_Automotive#:~:text=In 2015%2C TRW Automotive was,incorporated into ZF from 2016.

Not to be confused with TRW Automotive a big US conglomerate who are now part of ZF 

[Split_Pin]

Well fuck ☹️

Good investigating though!

[SiC]

Right bit of an update. First chance I've had to write anything proper.

Jack the bastard up again.

This time I put an earth clamp onto the motor body to test. @panhard65 suggested this as the motor might need an earth to function. While there is an earth to the main power connector, there is a 1kohm path between that negative terminal and the body. So well worth testing in case the logic runs off the body earth.

Unfortunately no difference.

The unit however does rattle when shaked which would suggest something loose inside. I don't think that's normal. 

My money is still on a dead unit and this second hand one is dead too. More on it in a bit.

I'm not sure my next path. Either I get another motor or replace the entire rack with a second hand unit. Btw I asked at BMW how much a new rack from them was .... £4k. Could buy another car for that 🤣

To replace the motor you need to undo the housing, turn a ring around to de-tension the belt inside and then a few more bolts for the motor to then remove. This is shown in ECU Testing (who repair these motors) video here:

 

I also put a post on a E89 Facebook group. The replies basically saying the fault I'm seeing to be the motor control unit and to send off to ECU Testing for repair.

However I had this response too:

Which begs the question to my mind on if they can't repair it (presumably don't charge) and replace with a used motor, why not just use a used motor to begin with?

£500 to repair versus ~£60 for a second hand 3-series rack (motor useful but rack not).

Or I just buy a replacement rack. Usually ime racks are a nightmare to replace. However looking at this and watching guides, it doesn't look too bad. Basically undo both tie rods, brace bars (albeit the bolts look crusty) and then 2 bolts for attaching the rack to the subframe. Bolts are either side of the jacking pad below. (Motor is the big lump in the middle)

Then a pinch bolt that's accessible up top (this is the bottom view) and slide the shaft off.

Honestly right now I'm fed up of being underneath this stupid car. I really don't want to jack up again to fuck around changing a rack while on my back. 

So I'm really tempted to punt this out to a garage where it'll be a million times easier for them on a lift. Plus changing a rack is a regular job for them rather than fucking around pulling racks apart.

Anyway while it was up on jacks again, I decided to remove the clutch delay valve. It's the thing my fingers are on below. Basically it slows the actuation of the clutch to stop hamfisted individuals not used to driving manuals (i.e. Americans) from smashing up their driveline from poor pedal work. 

Basically clamp off the line, remove the clips and pull off the thing in the middle. Then plug the clutch hose in to the remaining coupling and bleed.

Simple right?

Well first one of my clamps broke.

Then my Sealey pressure bleeder leaked air.

My Gunson eezi bleed had a buggered seal.

Used my vacuum bleeder. Went fine except pedal went soft.

Gah!

Ended up getting a oil filler to pump pressure jerry rigged into the Sealy cap. After about 2hrs fucking around with that I had a pedal again.

It drives soooooooo much better without it. Far snapper and smoother changes. Before it would regularly bunny hop when pulling off as the clutch wouldn't quite finish engaging as you released the pedal. Likewise quick pull-offs would slip the clutch.

 

At this point I was thinking "no more BMWs for me". Literally a moment later my neighbour popped round. "Have you got a BMW code reader to hand?" 

His M4 had shat it's soft close boot mechanism. We both questioned why the hell it really needs a soft close mechanism...

Our best guess is a wiring damaged somewhere. Anyway as I went for a test drive in my car I pass him, upside down in the boot with legs in the air, trying to figure what's buggered with it. 

He shouted "I'm buying a Honda or a Toyota next time!". He's been a life long BMW owner for years too. 🤣 (He does miss his utterly faultless Land Cruiser though)

[N Dentressangle]

That would be a garage job for me. Not very hard if you have a ramp, but a total PITA if you're on your back on the drive.

Life's too short

[SiC]

Yesterday I went for a drive in it. Mostly out of stubbornness that the weather was great and it'll be damned if I can't use it. 

First part of the journey was to the local shop. No PAS at all. Tbh about the same as my BGT and Rover P4. Heavy but manageable to manhandle it. 

Upon restarting, PAS returned - albeit with a warning light on. 

The drive to the seafront had it progressively more frequently pinging up steering fault on the dash. This is a good thing as it meant it was intermittently starting to talk to the rest of the car again.

Parked up, had a walk and ice cream.

Journey back home, full PAS and no warning light at all. 🎉

Naturally later on in the evening when moved the car around, the warning light came back on. But it does strongly suggest it is the module that is at fault rather than wiring.

[Zelandeth]

The thing that would scare me in your shoes is if it's having issues, what happens if it loses it's marbles?  I've visions of me driving down the M1 and the car suddenly deciding to instantly apply full left lock, or for it to just jam the steering up entirely.

Driving a car with EPAS that's misbehaving would just scare to hell out of me.

Still have nightmares about a hire car with it where it shut off the assistance when the over-aggressive stop start shut the engine off, at which point it became all but impossible to turn - think like trying to steer a coach without power steering, but with a car sized wheel.  It also reduced the braking effort to near zero.  It seemed to think the car was stopped when you were still doing walking pace, so I found this out halfway down Anderson Drive in Aberdeen while stuck in traffic.  Would never buy a modern Vauxhall after that experience.  How I didn't wind up embedded in the back of the Prius in front of me I can only attribute to what most people think as excessive following distance and luck.

[SiC]

42 minutes ago, Zelandeth said:

The thing that would scare me in your shoes is if it's having issues, what happens if it loses it's marbles?  I've visions of me driving down the M1 and the car suddenly deciding to instantly apply full left lock, or for it to just jam the steering up entirely.

Driving a car with EPAS that's misbehaving would just scare to hell out of me.

I do 100% have the same concerns. I'm reassured that I have never heard it happening on these though, despite it being common issue for them to full off the network. 

However I've only done short journeys since it started playing up for this reason. I won't be doing any longer journeys until it's properly fixed. If I really have to then I'll unplug the EPS from that rear connection box in the boot and drive with no assistance. While it's heavy at low speeds, it's manageable. Higher speeds you don't really notice it at all. Probably helps that I've driven enough old cars without PAS too.

No assistance is far better than unpredictable assistance. Not only the fear of it deciding to dart the steering one way but more likely it dropping out assistance around a corner making it unpredictable. But actually less of an issue loosing assistance at higher speeds as you don't need much to make a turn unlike at sub 20mph speeds. A lot of older EPS systems were pretty stupid where they provided the same assistance low down and then cut out entirely at higher speeds. I know my old Smart Roadster did that. Around 35mph from memory it would switch off assistance entirely and below it would provide full assistance.

[Noel Tidybeard]

would the pas module fall under Cobbles jurisdiction of complicated shite that can be un-broken?

[cort16]

TBH I would put this out to a BMW specialist who may  have dealt with the fault before. It's a nice car so worth spending some £ on it. Also  rolling around underneath it trying to diagnose a bastard of a fault isn't going to give you much love for it.  Pay the money and get it fixed then enjoy driving it through the summer.  By the time the summers over you'll have forgotten about the bill. 

[RayMK]

@SiC I admire your determined and skilful approach when getting your fleet up to your standards.  Perhaps you need something French and simple* like a Citroen C6 to help you appreciate BMWs a bit more 😀.  

[Fat_Pirate]

Reading this thread has led me here:

Dacia Spring 65 version.  

[Kiltox]

Just now, Fat_Pirate said:

Reading this thread has led me here:

Dacia Spring 65 version.  

Your 0% APR is costing you at least £3k versus buying pre-reg, do bear that in mind. 

[Hertz]

Surely if it's working intermittently then the rack rack and motor should be still ok? Must be a sensor or bad connection/earth somewhere ?

[colino]

Apologies if this has already been covered, but are the battery and alternator up to snuff?  They take a fair whack of power in operation and I just wonder if it is dropping out because it doesn't think there are enough magic pixies in the wire.