KwS's not M3, M3 Project (or, the M328i)

[Secniv 182]

8 hours ago, Gaz said:

Whats the outside temp sensor reading? 

I have a spare connector in the vicinity (front passenger side right) but no sensor.

Haynes manual a little unclear but doesn’t the (M20 anyways) use the blue temp sensor feed data to ecu to determine fueling?

Spent the evening replacing vacuum lines (they looked original) see how it goes tomorrow otherwise plan b.

[KwS 2429]

Well this is a familiar job, the old brake light switch failure.

A few drives ago I noticed the familiar "BRAKE LIGHT CIRCUIT" warning on the Check Control. Initially it was just a random warning that would pop up occasionally, but when checked, the rear lights still worked.

Unfortunately this escalated quickly, to the point where when I drove the car to and from work the other weekend, the warning would come up straight away, and sure enough, no brake lights were lit when the pedal was pressed. Eek. Back to the rear fog light when braking trick.

I touched on this error on my first E36, where I had the same issue. I replaced the switch a few times on that car due to faulty new parts, but eventually I got a good switch and the warning went away.

Replacement is fairly easy, once you know how the retention system works. If you try to fight the retaining clips, you will just make it much harder to get out.

This is the switch, in it "ready" state as it would be when installed in the car. The red collar is pressed into the body, and the plunger is short

To release the switch retaining clips, you need to extend that red collar by pulling it away from the body. There is one catch though, the plunger will not allow you to pull the collar out far enough, if the switch has been fitted, as the plunger doesn't extend out far enough. The plunger is on a ratcheting system, and needs to be forcefully pulled away from the body.

With the plunger extended, the red collar easily slips forward, and will allow the retaining clips to be pushed inwards, allowing the switch to be removed

To access the switch, you need to remove the lower knee trim. Its held on with three screws (one under headlight switch in the square recess, one under the dial for cluster brightness, and the other above the clutch pedal)

Once that is removed, the switch is mounted above the brake pedal

To release the red collar, you need to push the pedal down, extend the plunger, and then slip the red collar out. Only then can you violently wiggle the switch around until it comes out of its bracket.

This isn't an easy task to do. The trick is to either have the car engine running, or press the pedal down immediately after shutting the engine off, so that there is vacuum in the booster and the pedal can travel down far enough to allow the plunger to come out. A lot of people get stuck there, you cannot extend the plunger far enough if the pedal cannot be pushed down. I used a screwdriver to lever the plunger out, and then my hand slide the collar forward, whilst holding the pedal down with my other hand.

DO NOT release the brake pedal until you have the switch removed, or it will just push the plunger and collar back in thanks to the ratchet.

Once the switch is free, you can release the brake pedal and if you haven't already, disconnect the wiring connector.

New and old side by side. There was a bit of wear on the end of the plunger, so despite not having a date stamp, I suspect its original.

To fit the new switch, ensure the plunger and collar is fully extended, push the brake pedal down (doesn't need to be all the way like removal) and then push the switch into the bracket until it clicks in. Slip the red collar down towards the body so the switch can't come out. Now release the pedal, and you should hear it ratchet the plunger in. Plug the switch in, and test. You shouldn't have any warnings on Check Control now, and the brake lights should work when the key is ON, and pedal is pressed.

Reinstall the trim, and away you go. Done.

[KwS 2429]

Ok, so obviously i've been trying to sell this car for a bit now, have had more time wasters with this car than any car i have sold previously. A couple of people that were "super keen" have even test driven the car, only to suddenly not be keen based on the KM (i've made the KM pretty clear), or because it's not "A real M" (also obvious from the start). I've been offered as low as 7K, and even a couple of offers in my ballpark that I have accepted, only to never hear from them again.

So i'm seriously considering keeping the car for a longer period. That would mean finishing the list of things I want to do to the car (mostly cosmetic stuff), sorting the suspension (upgrading, either BC Golds or maybe Koni, and poly bushes) and a cert.

On a whim i popped to Pick A Part today and got a good haul. Turns out they have a coupe there, so grabbed a few things I needed, including the boot carpet and plastic trim.... which means I can finally f**k off the boot install. I still forgot the ambient temp sensor, which was the whole reason i went >_< Next time.

[Young Thrash Driver 1020]

@qube wants your boot carpet ?

[qube 3570]

The burberry covered disaster?? Why would i want that hahaha

[KwS 2429]

Well, it will be $1 Res on tardme when I pull it out, get in there guys! ?

[Olaf 3341]

16 hours ago, qube said:

The burberry covered disaster?? Why would i want that hahaha

Go on, you know you want to ?

[qube 3570]

9 hours ago, Olaf said:

Go on, you know you want to ?

If my car sells i may go for this, burberry cover and all!

[KwS 2429]

Its been a while, for two main reasons, but I'm still here, and for now, so is the BMW.

The first reason has been that despite putting some KM on the BMW, it's been pretty reliable and solid. I even ticked over the magical 300,000KM mark the other week.

The other reason is that a while back I was offered a car that I basically only have one chance to own in my life. There is a very long story around how I still don't have that car, but basically I have been trying to sell the BMW to get funds and space to buy the other car, but without success. I have had a stupid amount of stupid people wasting my time, which infuriates me, but still no one has fronted up with the cash.

This leaves me in a limbo of sorts. I'm reluctant to give up on this other car and keep the BMW, as I likely won't get another chance for one again, but I also can't keep dropping the price and losing my arse just to push a sale quickly. So since I'm still stuck with the car, I'm also limited on spending money on it, or working on it. There are a few things that I will do to the car IF I keep it, but at this point I still don't know what's happening.

In the meantime I have picked up a few things from Pick A Part. They had a coupe with a complete boot carpet, which I picked up so at some point I can rip out the boot install and go back to having a functional boot. I also grabbed a few cosmetic bits that were a bit shabby on my car. All cheap bits that aren't easy to get.

One of the most important cosmetic bits I got was a new headlight switch. I hated seeing mine every time I drove the car because it was badly worn/scratched/scuffed. It also didn't light up like it should. You can see how horrible the legend around the dial looks, but even the I/O on the vent above is badly worn.

These are super easy to remove, with only one screw on the underside of the dash surround, going up into the switch housing. Remove that, and gently pull the switch forward (I hold it by the dial). Its clipped into place in the top of the vent, but it'll come free with some wiggling. The wiring is fairly short for the foglight switch, so take care not to pull too hard or you can break that switch. The headlight switch wiring connector has a collar that twists around and the plug will come out.

The replacement I sourced has a broken switch for the headlights, so when you turn the dial it doesn't click like it should. That's OK, my current one works fine, so I will swap them over.

First pull the dial off. It's a press fit

There are two things to note when that is removed. First, the light pipe in the back, at about 10-12 o'clock position. This is how the bulb feeds light to the notch on the dial, so it lights up. The other is the large plastic nut. I used a set of large needle nose pliers to turn this and remove it. Once removed, the whole switch will come away from the fascia.

This is a really good time to replace the bulb, which is inevitably blown. This can be done with the switch still fitted to the fascia, but it's easier to push the bulb out the front, than to pull it out the back.

The bulb is in a large plastic holder. If you push on the top of it, it will push out of the back of the switch

The bulb is a small "grain of wheat" 286 bulb. Now, I believe the original BMW bulb was 0.3W and about $10 a piece!

Madness. In the past I have chosen to use the much brighter 1.2W bulbs readily available on eBay. They do obviously run hotter, but other than a shorter lifespan, there doesn't seem to be any issue running them, but do so at your own peril. I went this route again this time.

Now it's time to strip the good switch from the old fascia.

With a new bulb fitted, install the tube into the good switch. The end of the tube is keyed to only go in one way, but be careful that the bulb passes clearly through. If the bulb isn't seated correctly, you can smash the bulb inside the light switch.... I found out the hard way.

Now install the good switch on the good fascia, reinstall the nut and dial. Plug it into the car (without installing it) and test that everything works as it should. It should light up with the key on. If all is well, reinstall it into the dash and fit the screw.

So much better!

I couldn't stop there. I had the bulbs out, and I knew one other thing wasn't lighting up in the car; the climate controls.

This is another thing I had to fix in the first M3, as that also had neither the headlight switch or climate controls light up when I got it.

This is also an easy fix. First pull all four dials off. They are a friction fit.

Next remove the two screws (one under the fan speed dial and the other under the vent control dial).

Now the fascia can be gently pried forward until it pops off

The back of the fascia is pretty cool. It has a series of light pipes to distribute the light from the single little bulb, to all of the areas around the dials that need to light up. The buttons (recirc, AC, demist) are all lit with little LEDs on the back plate.

The little bulb lives dead center near the top of the unit. Gently pull it forward and it will come out of its holder. There is some discolouration around mine, and it did have a bigger 1.4W bulb fitted by the previous owner, but no distortion of the plastic or anything. Pop a new bulb in and turn the lights on.

Now clip the fascia back on, insert the two screws, refit the four dials and you're done.

Bling bling.

And with all the other light up stuff

The last thing that didn't light up was the ashtray. Turns out the whole bulb holder is missing, but not to fret, I picked up a replacement at Pick A Part today also.

A non-smoker package pocket to replace the ashtray. Fixes the light not working, and also gives me somewhere to put my phone. Win.

Great success. Now I can see things in the dark.

Hopefully soon I will know what's happening with the car. Either it'll go to a new owner, or I will be ripping the boot install out.

[Secniv 182]

1 hour ago, KwS said:

The last thing that didn't light up was the ashtray. Turns out the whole bulb holder is missing, but not to fret, I picked up a replacement at Pick A Part today also.


 A non-smoker package pocket to replace the ashtray. Fixes the light not working, and also gives me somewhere to put my phone. Win.

 Great success. Now I can see things in the dark.

Hopefully soon I will know what's happening with the car. Either it'll go to a new owner, or I will be ripping the boot install out.

Love your attention to detail and thanks for the ashtray delete/phone holder idea.

GLWS and sometimes when chasing dreams figuring out the how can come later  

[Eagle 1679]

Yeah im guessing the "high k's" isn't helping the sale either, but in my experience 300k+ BMW engines have always run clean and strong. Im sure yours is the same.       

Edited April 28, 2019 by Eagle

[KwS 2429]

Likely, but it's not like other M3s are spring chickens either. Most are over 200k and still twice my asking price. 

Engine runs as good as my old one that had 200,000k on it. No smoke, no oil or coolant use and minimal leaks (damn cpv weeping). Neither its condition or how it runs shows 300,000km, it's literally only the number on the cluster. 

I could've been like the previous owner and try to pretend the cluster wasn't original to this car and it's really only done 200,000km, but I'm not an a**hole. 

Edited April 28, 2019 by KwS

[KwS 2429]

Well, the time has come. I'm keeping the BMW for the foreseeable future, so the only logical next step was to drop some dead weight, and pull out the subs.

The decision to keep the BMW wasn't one I took lightly, but I'm not sad or disappointed to be stuck with it. I actually quite like the car.

There are a few things that didn't suit me about the car though, and having a bunch of useless weight sitting over the rear axle is one of those things. The boot install looked nice, but it really killed my enjoyment of the car. It sounded bad, and had been hastily thrown into the car.

The main issue was that the capacitor on the driver's side wasn't actually secured by anything and was just sitting on top of the battery. This meant that every time I cornered hard (like an M3 should), the damn thing would fall over and go for a scoot along the boot floor, until the power wires restrained it.

It was sitting on a block of wood

So out it all comes. I'll tell you what, getting the sub box out was a mission. First out comes the floor panel and amp from the spare wheel well.

Then the side amp, and capacitor come out. This gives enough room to shoehorn the rest of the trim and the box out of the boot opening. Turns out the box wasn't secured at all and was held in with hopes and dreams.

It's a big box, that's for sure. I forgot how big a coupe boot actually is!

In goes the carpet from Pick A Part, after a quick vacuum

Even though this spare wheel doesn't hold air (buckled and leaks at the bead), I still put it in the boot as it helps to hold the carpet up, and also helps with weight balance. I need to find another wheel at some point. The wheel and tire weigh about the same as the amp that was in there, it was a beast.

The previous owner butchered all the standard wiring for the speakers, so unless I want to run a whole lot of new wiring, I'm stuck with running the speaker amp. Thankfully I actually like this one as it looks cool, and doesn't take up too much space. Even the wiring going to this is a mess though. Yes, that is the pair of RCA connectors (usually used as one pair for front, and one pair for rear), split out to fill all four channels, front and rear. I'll rejig the RCA cables that went to the sub amp, and use them for the rear speakers so fronts and rears are split properly.

The final result isn't perfect. The carpet needs some fettling to tidy it up, and the battery is the wrong size so the plastic cover on it doesn't quite fit properly, but otherwise, it's now a fully functional boot.

Driving the car to work yesterday and the lack of weight is noticeable. It's not major, but it doesn't feel like you're dragging the backside around anymore. I would've pulled a good 20-30kg out.

The next steps for the car are in motion. I have a set of BC Gold adjustable coilovers to go in, and a nice Purple Tag E46 steering rack to replace the horrible 3.0 M3 rack, which is the dumpster fire of steering racks. I'll also be rebuilding the vanos, since I already have the parts to do it, just need the time.

[M3AN 4016]

I'm sort-of glad you decided to keep it as you know how to treat it.

I suspect your ownership will uplift the value anyway, so I don't think you'll lose from it.

 

[bradgalbraith 218]

I bet it pulls like a freight train after removing all of the heavy junk in the trunk!

[_ethrty-Andy_ 2136]

worth adding into your post on the brake switch that there are two types, one if the car has OBC (4 pin), one if it doesnt (2 pin)

[KwS 2429]

1 hour ago, _ethrty-Andy_ said:

worth adding into your post on the brake switch that there are two types, one if the car has OBC (4 pin), one if it doesnt (2 pin)

Eww, who wants a car without an OBC? Peasants.

[KwS 2429]

Fixed the speakers today. Since removing the subs and amp I had no power wiring to the speaker amp (piggybacked from sub amp). 

Ran new power and ground wires direct to battery, with a fuse in the +12 line, which the original install was missing, just in case. 

Turns out the speaker wiring at the amp was all on the piss too. The front speakers are daisy chained so only use one output on the amp, so what's the other "front speaker" wire? Well, seems its only purpose in life was to make a cracking noise through the speakers. 

Without the subs, and having the speakers wired properly, I could finally have a go at tuning the amp. Now I have decent sound without distortion. Not perfect, but good enough. Better than listening to my leather vaders squeak on the leather armrest... 

The epic failures of the previous owner still keep haunting me. 

[KwS 2429]

On 3/15/2019 at 3:03 PM, Gaz said:

That could cause it to run rough, see if you can find one

Oh and can also 100% confirm what I said, that the ambient temp sensor doesn't do anything. Fitted one, temp on obc good, idle still rough. 

[KwS 2429]

Ah yes, that time again. It's not my M3 if it doesn't involve rebuilding the Vanos at some point.

If anyone has forgotten, I have previously rebuilt the Vanos unit on my old M3, and what a nightmare that was. Lesson learned, don't use cheap tools.

Being that this car has 300,000KM on the clock, and the previous owner has no history of the Vanos ever being rebuilt, I felt it was prudent to do it. This made even more sense, since when I first got the car I ordered a full Beisan rebuild kit, as the Vanos was completely dead (turned out it was just a sensor issue), so had a kit sitting around.

The previous owner had the Vanos off the head back when they had the head work done, but when I asked, he confirmed that it was not rebuilt at the same time (argh, the hardest part is taking it on and off, why not do it then?!). This gave me some hope that maybe it wouldn't fight me like the last one did.... or on the flip side, there was a chance the previous owner had been kind enough to round off the bolts or something on reassembly.

Anyway, with a nice clear day off work, I got stuck in.

I won't do much step by step work in this post, as it's covered in my previous rebuild, and also on Beisans website.

One reason I had been putting the job off a little bit longer was that the valve cover wasn't leaking, and I really didn't want to pull it off again in case it starts to leak. Oh well, Here goes.

Argh, bugger, so much for not leaking. This little bastard never seems to want to seal. It's a new gasket, with a new rubber washer... and it's still leaking.

The inside of this engine is bloody amazing for 300,000KM. Its obviously been looked after and well serviced. The previous M3, with 100,000KM less, was almost black on the inside. This is lovely and golden brown.

Before you can do anything else you must get the engine up at TDC. This involves having the No.1 cam lobes for intake and exhaust pointing up and towards each other and making sure the crank pulley mark is lined up. I had a hell of a time last time, as the Beisan instructions are incorrect, and the timing mark is hard to find, tucked down behind the crank pulley.

Strangely, on this engine there seems to be a critical change. Not only does it have the marks behind the pulley, but it finally also has it stamped into the front of the pulley! Not sure if this was a South African Market difference or just a difference between 1994 and 1995 engines. I still had to use my old iPhone to see it, but it's better than having to try and see it behind the pulley.

As expected this little piston nut gave me some anxiety. To undo it, you use a 7mm spanner on the nut and a 4mm 6 sided socket on a ratchet to hold the shaft still. The 4mm hex is well known for just shearing off, and then you're having a bad day. Thankfully although it was tight, mine came off just fine.

One part I have been asked about was to give more details on the removal of the oil pump driver when removing the Vanos unit. This is a little disk that sits on the back of the unit. It's circled here

My previous unit was so sludged up that the driver disk was stuck to the unit, but in this case it was nice and free. The risk here is that if dropped, it takes a swift one way trip to the bottom of the sump. Turns out, it's easy to keep it in place. Use one hand to hold and pull the Vanos forward, and the other to hold the disk. There is plenty of space around it.

The Vanos has been leaking externally leaving a mess down the front of the engine

And on the underside of the unit

Of course the unit got scrubbed clean, and the engine was given a quick scrub and clean.

Removing the cylinder cover on the back of the Vanos unit gave me my first surprise. This is meant to have a seal pressed into it.

The seal was sitting on the cylinder, having fallen out of the cover. It was well perished and crumbled when you so much as looked at it

Organised chaos

Part of the rebuild was to clean and test the solenoids again. I had previously done this when I redid the seals on the solenoids, but I wanted to be more thorough this time around. I got sick of having to try and jam the wires from the battery connector into the solenoid connectors, so quickly rigged up a tester using bits from the garage. Now all I have to do is plug the solenoid into the connector, plug in the 9v battery, and hit the button. Easy.

I can use the same tester on injectors too, as long as they use the JPT connector.

With the more thorough cleaning and testing the solenoids when from a nice click, to a firm crack every time they were actuated. I don't think it'll make a difference, but at least now I know they are working as good as they can.

I also resoldered the solder points on the solenoids, as they were looking a bit old.

I also chose to bridge the solder points. I don't know why BMW chose to run it through that little circuit board instead of direct (it literally goes into the outer solder point, across a track on the circuit board, and out to the solenoid via the inner solder points), but this is a common mod to ensure reliability.

With the Vanos unit rebuilt, It was time to do the rattle fix on the splined shaft

This one wasn't anywhere near as bad as the old M3s one, but good to take any play out of it.

Reassembly was the reverse of disassembly.

So, what's the story now? Well, the seals take a few hundred KM to bed in properly, but already the car has perked up down low and has noticeably more punch off the line. Up top is about the same, but it's quicker to get there. It's proper rapid.

The idle issue has not changed. This is really disappointing; I was hoping it would be the solution to everyone that is having the same idle issue, but sadly not. Back to the drawing board on that issue.

Since the WOF runs out at the start of next month I have decided to pull the car off the road shortly. I have a set of BC Gold coilovers and a purple tag steering rack to go in, along with some other bits coming from the States (thermostat, reinforcement plates etc). Once I get back from holiday, I'll book it in for a Cert, and see what happens there.

[Secniv 182]

What reinforcement plates you doing?

[KwS 2429]

Just front and rear strut mounts. Don't want the adjustables poking their way through my towers. 

[Olaf 3341]

42 minutes ago, KwS said:

Just front and rear strut mounts. Don't want the adjustables poking their way through my towers. 

Very sensible!

[KwS 2429]

In my quest to smooth out my idle issue, I wanted to remove and check the DME and VNC units.

The DME (Digital Motor Electronics or ECU in normal cars) and VNC (Vanos control unit) are both stacked in a little compartment at the back of the engine bay, under the cowling. There are two things that these units are known for; A, getting waterlogged in that compartment and B, cracking solder joints.

This is where they live in a RHD engine bay. On the LH side, and on the M3, behind the coolant expansion tank. ALWAYS start by disconnecting the battery. You don't want to short this stuff out.

First, the coolant tank needs to be moved. This is clipped in at the back, and hooked into a tab at the front. The rear of the tank will just lift upwards out of its clip and then side toward the rear of the car to disengage the front tab.

This allows you to undo the 5 screws that surround the black panel. A 1/4" ratchet was the best for fitting in here.

The RH side of the panel is hooked into a little tab. You need to pull the LH side towards the front of the car, whilst holding the loom against the firewall (to unhook it from plastic panel), and then slide the panel to the left.

Then you have a big gaping hole with wires and control units in it. This is the point where you can tell if it's been full of water in there or not. Mine, thankfully, looked pretty dry. A bit dusty if anything.

On the bottom, with the big connector, is the DME. Up top is the VNC, with a smaller connector.

I found removing the DME connector from the DME before sliding the unit forward, was a lot easier than trying to remove the DME first, as there is limited space due to the fuse box.

To remove the DME connector, the silver metal locking tab needs to be lifted up, away from the DME. This will allow you to tilt the wire end of the connector away from the DME. The other end of the connector is hooked into the DME and to disengage it you need to tilt the connector away from the DME until it slides out.

The DME is then friction fit into its mount. It will slide forward with a bit of pressure, and come out.

With the DME out and on the bench, I needed to disassemble it to inspect the solder joints. Normally this requires bending tabs on the bottom of the unit, but my DME has obviously been open before, and these tabs are missing.

Then there are a bunch of screws top and bottom. The little ones are Torx 8, which thankfully being an ex-Apple Computer technician, I have T8 drivers just kicking around.

With all the screws out (including the four large ones in the below photo), the casing comes off and leaves bare boards

Now, the DME3.3 used with the S50B30 is a two board setup joined by a ribbon cable. This is fairly straightforward, only complicated slightly by the fact that one layer of the boards has its own pins in the connector, and needs some specific conditions to remove the pins. The pins are the top layer

In the bottom corner of the boards there are two little plastic retaining clips on each corner of the board. These pull apart to release the boards, and then the boards must be carefully prised apart. 

You need to separate them at least as far as the above photo, if not slightly further. Just don't damage the flex cable between the two.

With the two boards apart, you need to carefully pry the layer of pins out of the connector. There are a couple of clips on the back of the connector that need to be undone (pre-broken off on my DME), and then using a little flat blade screwdriver, wedge it between the top of the plastic around the pins, and the lip just above them on the casing. If you have enough angle on the boards, this should allow the pins to pop out backwards

The DME should then open out into two boards

This is also the same procedure required to chip the DME, which I figure is why my DME has been open before. There were obvious witness marks on the tune chip socket. The chip that would be replaced is circled below

Anyway, that's not what I'm here for (for now). What I wanted to check for, were cracked solder joints. Anyone who is a long time reader of mine will likely remember I fixed Nicks Vitesse by fixing solder joints in his ECU. This is the same thing I'm looking for here.

A quick nosy around and I spotted a couple of very suspicious looking joints. Most of them were on the large diodes on the main board.

I fired up the old soldering station, cracked up the temps, and went to work resoldering the joints. In the end I think there were about 6 joints that I resoldered.

Reassembly of the DME is just the reverse of disassembly. Hook in the pins, press the boards together and then reinstall the casing and screws.

Next was to remove the VNC. This is a weirder mount; you need to slide the VNC towards the rear of the car, and then down, to get it out. The connector has a tab that slides across to unlock and remove it.

A bunch of little screws hold the top cover on, and once removed, reveal the magical guts of the unit that makes Vanos work.

And as a reminder of how special these early M3s were, all the original VNC chips have a handwritten sticker on them. This is also the chip that gets replaced when you chip the car (both the DME and VNC need to be chipped).

I completely removed the board from the housing, but found nothing out of the ordinary here, so reinstalled and reassembled it. Refitting the VNC to its mount is a pain. It needs to slide backward and up, and then forward to lock it in.

The connectors and cover then go back on, and the battery can be reconnected.

The result of this work was... nothing. No change at all. Still runs and drives the same, but at least I know it should be more reliable in the future. I now also know how to remove the DME and VNC to chip it if those "Group N" chips on eBay tempt me too much.

[KwS 2429]

Another part of trying to sort the idle is to replace the idle control valve, which has been a bit suspect from the beginning.

I don't particularly enjoy taking the intake off, but its the only way to get to the idle valve.

I cleaned the idle valve a while back, but obviously it was still suspect. Even after cleaning I was still getting a reading of zero in DIS for idle air flow (I haven't had a chance to test since replacement). 

After some research it turned out that the S50B30 idle valve is shared with the M60/M62 BMW V8 engines, so although its bigger and not shared with the other I6 engines, it's not too hard to source one from an E34/E39/E38.

I got a good used replacement, and got to work pulling the intake out again. Thankfully last time I had it all off I chose to fit a pod filter instead of the standard airbox, as that was one part that pissed me off a lot when reassembling; refitting the airbox. Taking the plenum off doesn't take too long, it's just a bit fiddly.

Here we go again

Out came the old valve. The only difference between the M6x ones and S50 is that there is a rubber grommet on the M6x ones. Once you pull that off, they are the same, even down to Bosch part number.

It became obvious that despite me cleaning it, the original valve was still sticking, and it moved nowhere near as freely as the used replacement. An easy test of how freely they operate is to twist/shake the unit side to side and see how easily the shutter inside it moves.

 

 

The old one needs quite a firm shake to move the shutter, whilst the replacement moves very freely. I suspect this is how the original one moved in DIS but may not be working correctly. With a full whack of voltage to fully open or close it (as the DIS test does), it works OK, but you can't finesse the movement and tweak it just a little.

With one of my previous orders, I had ordered a replacement mount for the valve, as the old one was brittle and broke last time I removed it (hence the zip tie in the above photos). On went the new mount.

I fit the replacement valve, reassembled, and tested. It seems the idle acts a bit better than it did, with noticeable changes when load is applied at idle, but it's still rough and misfiring at idle, so obviously the idle valve was an issue, but not related to my original fault.

Edited June 2, 2019 by KwS