Unreliable German Car on a Silly Journey

[JumpingFrog]

So, small back story, I was living in Russia from late 2020 until earlier this year. I had to leave a lot of stuff behind, and my wife is still living there whilst I liquidate my investments and  build up 6 months of financial evidence as required for a UK visa (not straight forward). Since I still have a valid Russian visa, I decided to do the most sensible thing - buy an overpriced used car in England, drive to Russia and spend one last New Year's there, collect my things, and return as soon as the snow is gone.

Chosen victim was a 2009 320i Touring (E91), with what I now know to be the highly problematic N43B20A 2.0L petrol engine. Collecting it from Leeds, I was immediately greeted with an "Increased battery discharge" warning that wasn't there when I viewed it, uneventful enough drive home, didn't make any bad noises, pretty smooth.

Did almost nothing before taking it for an MOT, just removed the horrible rear tint and changed nasty wheel centres. Passed with only front tyres as an advisory (which I knew about already). Seemed like all was going well. So I gave it a full service, including coolant flush (with coolant mixed for -40c), fresh oil and filters and also replaced the battery that turned out to be the original from 2009, discharge warning disappeared.

Next, I decided to buy a space saver and even checked it would fit, turns out the wheels on the car are from a later BMW and the rear has spacers and long wheel bolts to make them fit. After about an hour of gentle persuasion (read lots of heat), I managed to convince the spacers to part company. Space saver then fitted fine but had to make a mental note to buy shorter wheel bolts before I leave.

Since this car is the relatively high spec "business edition" with sat nav, I bought a fancy MMI box (MultiMedia Interface) that interfaces with the 2009 era iDrive system and a modern  smartphone with Android Auto, fitting such a thing naturally requires taking the whole dash apart.

At this point, I thought I had a working car, the only fault code in the ECU of any significance was for the infamous NOx sensor (BMW decided to fit a NOx catalyst to petrol cars due to the stratified charge mode), which apparently doesn't cause a warning light and usually has no affect on the engine other than maybe preventing use of stratified charge mode. So I booked a ferry, did my final preparations like tyre pressures and headlight adapters, and hightailed it down to Dover. But also realised I hadn't actually managed to buy wheel bolts for the space saver.

On the trip down the M6, I quickly got an engine warning light, plugged in my basic code scanner and all I could see was "Post Catalyst Fuel Trim Via Oxygen Sensor System Too Lean Bank 2". I decided maybe this is just a dying lambda sensor, engine seemed to run okay, fuel consumption was okay, temperature was okay, plus it has 3 lambda sensors, not just one and I didn't have time to stop. However, later on I think I noticed (or maybe my mind is playing tricks on me) that the cold idle is slightly rougher and there are occasionally small stumbles (almost like a slight misfire) when cruising. Crossing my fingers this isn't the very expensive direct injectors.

The journey across Europe was uneventful, successfully verified it could do 100mph on the autobahn (but rear wheels gave bad vibrations around 77mph), first night was Dortmund, Germany then Poznan, Poland, followed by the very pleasant Augustov (also in Poland) and finally Ape, a small village in Northern Latvia. The engine warning light had actually gone out at some point in Germany, luckily for me a parking light bulb failed shortly after so I wasn't left with an empty dashboard for long. Managed to pick up some parts in Latvia (post-cat lambda sensor, spark plugs, a spare coil pack, and the shorter wheel bolts I forgot to buy) - I assumed finding decent parts for a BMW might be harder in Russia given sanctions.

The Estonian border with Russia appeared to be the most trouble-free one from reading Russian social media channels (other borders apparently take 3 days), you book a time online, turn up and hopefully cross without a queue. However, as soon as I entered Estonia things got worse, first I got "Engine malfunction reduced power" whilst decelerating from 90km/h to 40km/h for a village. Code scanner just showed the same error from earlier, plus the engine warning light was back. Although, restarting the engine cleared the reduced power mode error. Next, about 10km from the border I was pulled over by an unmarked Estonian police car, they checked all my documents and became quite rude when they saw the Russian visa in my passport. Of course, I understand why, but I'm not sure such attitude is helping normal people.

I arrived on-time for my 10am reservation, the first step was to wait in a holding car park, there were only around 15 cars there but lots of trucks, trucks seemed to not wait too long, but no cars moved at all. At 3pm they called 6 cars forward including mine to the checkpoint proper. Forward progress was short lived, we ended up sitting there another 5-6 hours watching the empty inspection area. The Estonian checks were mostly painless, although still unfriendly, threatening to fine me for not having EU car insurance - they weren't happy with the UK document despite it stating clearly that EU cover was included.

Russian side was definitely the main issue, things just happened very very slowly. Fairly expected bureaucracy with temporary import paperwork, but the actually staff were surprisingly friendly. At about 1am, when I thought everything was done, I found out what the main reason for the bottleneck at the Russian side was - they send all cars and trucks for an x-ray scan. However, all they have is one "portable" scanner mounted to a truck which takes between 10-20 minutes per vehicle. Cars have to drive up onto a rickety platform to be scanned which made things even slower.

The x-ray was done and my paperwork finished at 3:30am and they finally let me continue and at last fill up with 50p a litre Russian petrol.

After an uncomfortable and cold night's sleep in the car, I was on the way to Moscow and even managed to sort out car insurance en route. Disaster struck again, about 500km from Moscow, when I got my first puncture ever after hitting a box spanner left on the road. The tyre ended up unrepairable with a rather big cut through the side wall. Fortunately this was just 6km from the nearest town and I was relieved I had the space saver and everything to fit it. However, finding 18", wide, low-profile tyres in rural Russia isn't straight forward. After trying all the tyre shops in the town with my broken Russian, I ended up with only one option, an overpriced used tyre, slightly too big (but "only" 1.1%~ difference) to get me to Moscow. Eventually arrived in Moscow at nearly midnight after only 6 days and 4000km on the road. Rather surreal driving through the centre of Moscow in an English registered car again.

Now I'm working out what to do to make sure I can get back, finding decent tyres is proving hard work, all tyres here from reputable brands seem to be 3+ year old stock of models now discontinued in Europe. The only "fresh" tyres I can find are Chinese. I'm also debating what to do about the engine warning light, first I'm waiting on a Windows computer to read the engine parameters so I can decide if it's "serious". Somehow was less worried about the Herald letting me down than this modern thing... Don't suppose anyone has any experience with diagnosing BMWs?
 

Edited October 3, 2023 by JumpingFrog

[JohnD]

Wow, JF!   Puts the 10CR in the shade!  Good luck!

John

[Nick Jones]

Ahhhh……. Man needing reliable transportation buys 14 year old BMW instead…… 

Sorry, you’re suffering enough already.

I wouldn’t worry too much about 3 year old tyres provided they are not Continental or Avon, which seem to start falling to bits about that age. Also some of the Chinese made tyres aren’t that bad (Triangle are that bad though)

As to the engine management issue, I have no idea. Presumably you’ve not actually changed the Lambda sensor yet? Could be that…. Though swapping that is not exactly a risk-free undertaking.

I expect you’ll win though.  Hell, you got to Mongolia and back in a Herald after all.  
 

May the Force be with you!

[JumpingFrog]

On 10/2/2023 at 9:14 PM, Nick Jones said:

Ahhhh……. Man needing reliable transportation buys 14 year old BMW instead…… 

I don't know, the E9x series is quite well engineered in many areas. Definitely it's a nice car to drive, and behaves well, responsive... But main problem is expensive parts and overuse of plastics.

This engine is just very very complicated, probably they got about all the could from a naturally aspirated 4-cyl 2L by adding VVT on both cams, direct injection, variable length intake manifold, balance shafts, electric water pump, ability to do efficient stratified cruise and most scarily of all oil pressure regulated by ECU to reduce fuel consumption. 170hp and 45 mpg seemed an appealing enough proposition...

On 10/2/2023 at 9:14 PM, Nick Jones said:

I wouldn’t worry too much about 3 year old tyres provided they are not Continental or Avon, which seem to start falling to bits about that age. Also some of the Chinese made tyres aren’t that bad (Triangle are that bad though)

Tried several times to find matching tyres for the new fronts I got in England (Goodyear Eagle F1), but every place I've ordered them from have rung me up and told me no can do. Goodyear website states no shipments to Russia, yet at the same time I can still buy various Goodyear branded aerosols and greases at my local autoparts store... Today gave up and ordered Nokian tyres instead, they seem to get okay reviews. Cost is still a fortune by Russian standards (about 150 GBP each).

On 10/2/2023 at 9:14 PM, Nick Jones said:

As to the engine management issue, I have no idea. Presumably you’ve not actually changed the Lambda sensor yet? Could be that…. Though swapping that is not exactly a risk-free undertaking.

I didn't change it yet, it has 3 lambda sensors but the error for bank 2 post-cat makes no sense. Basically, bank 1 is cylinders 1 and 4, bank 2 is cylinders 2 and 3, each bank has its own cat (e.g. it goes 4-2-1), before each cat is a wideband lambda sensor and then there is one more narrowband "monitoring" sensor where the two cats merge together. I only bought the narrowband post-cat sensor, but in hindsight I suppose one of the pre-cat wideband sensors is more likely the culprit. Perhaps I should just start with the old fashioned method of checking the plugs...
 

On 10/2/2023 at 9:06 PM, JohnD said:

Wow, JF!   Puts the 10CR in the shade!  Good luck!

John

Thanks! Although I wasn't trying to put anyone in the shade, just collect my stuff from a sanctioned country 

Edited October 3, 2023 by JumpingFrog

[Nick Jones]

3 hours ago, JumpingFrog said:

This engine is just very very complicated,

Yes! This!  Too complicated.  Chasing green targets and trying not to compromise on performance. And "value engineered" to survive the warranty period (just, most of the time).  But there's nothing green about building a highly complex machine which doesn't last.    Easier to forgive maybe if they didn't absolutely take the piss on parts prices and pay scant regard to maintainability.  Not really any worse than Audi or Mercedes, maybe even most of the rest.  Then there's JLR .

Doesn't make me want to own any of them.

3 hours ago, JumpingFrog said:

but the error for bank 2 post-cat makes no sense.

I wonder if it's a comparison problem.  As I understand it, the post-cat sensor is there to allow the ECU to monitor cat efficiency.  If there's only one post-cat sensor for two cats (more value engineering), then this is made more complex.  My take on the message is that there is an issue with bank two, probably not the post cat sensor.  Either the pre-cat sensor giving odd readings, the cat itself or actual poor combustion in 2/3 due to dodgy injector, coil, plug or whatever.  A plug check might give a clue.

[JumpingFrog]

It's mostly behaving itself, although the fuel economy in Moscow traffic isn't good, under 30mpg. But that's what 15km/h average journey speed does I guess, and also why everyone I know has an automatic. It's been getting Gazprom's finest "100 octane G-drive" fuel because I'm too scared to put standard 95 in it.

Finally got the tools I was missing (mostly special plug socket with swivel head) and had a look at it this morning. First started by pulling the plugs, the old ones looked like this (cyl. 4 at the top, 1 at the bottom):

Okay, not that old actually. But clearly the wrong ones. Correct NGK ones (the only ones apparently), have a 0.9mm gap, 24.2 mm thread plus 9.3mm spark position, the old incorrect Bosch ones have a 0.7mm gap and 26.5mm thread plus 6mm spark position.

All the differences aside, it doesn't actually seem to have changed how it runs at all. Just as rough when cold and a quick spin round the block makes me think nothing changed. In terms of condition, plug for cyl. 1 was definitely the odd one out, smelt strongly of fuel and definitely shows signs of carbon build up further up the insulator. Still nothing terrible and a long way off fouling. If such a plug came out of my Herald I'd think it's a bit lean if anything...

Apparently the usual failure mode for these injectors is to not close properly, leaking fuel which upsets the ECU as it tries to trim the fuel banks. Compared to some photos online, this isn't that bad, there are stories of plugs fouling in 100 miles, but it definitely isn't optimal either. The only service history I got with the car was the last service, where they fitted new plugs and a new coil pack to fix a misfire. Cylinder 1 had the new coil pack, all others were from 2012 or 2015. Clearly what they did didn't fix the problem.

Dipping into the computer, there are a lot of codes, hard to know what's what:

• 30EA - NOX Catalyser sulphurised.
• 2AF4 - NOX Sensor electric error.
• 2AF2 -  NOX Sensor linear error.
• 2AF6 -  NOX Sensor binary error.
• 2C7F - Bank 2 O2 sensor post-cat trim error.
• 30DA - NOX sensor heating time error.
• 2A99 - Exhaust cam correlation error.
• 2AF8 - NOX error in overrun mode.

I'm not so worried about the NOX ones, there is a fix for all this I can do when I return to England which is basically to delete/emulate the NOX sensor because making the system work again is beyond economic repair and the NOX catalysers only had a 100000km life span anyway.

The only other interesting one is the cam correlation error, reading online there's a high chance this is the VANOS (VVT) solenoid and all I need to do is clean it out. This is probably also the cause of the random reduced power mode I saw in Estonia. Not too scared about this, will clean them tomorrow.

Poking around at the "operational smoothness" values (I think this is via knock sensors), I can see some signs of problems with 1 and 4:

From this and the plugs, my best guess at the moment: Injector 1 is going bad, and cylinder 1 is running rich. The ECU is trimming for this but since they share the same feedback loop (the same catalyser and lambda), they must be trimmed together so bank 4 ends up lean as well. From this hypothesis, I'm assuming that the post-cat bank 2 error is a red herring, and the ECU doesn't really know where the error is, like Nick says, the ECU knows something doesn't correlate, but can't guess where due to cost engineering and only having one post-cat sensor.

Backing this up, the live "adaptation" data shows it's pulling back 20% from bank 1, which seems high (almost 10x) compared to the value for bank 2:

Clearing the codes took the error way, of course I know it will come back. I'll give the VANOS sensor a clean, but fixing this injector is not really something I think is going to be done easily in Russia. Unless I can find a good used one that is, this engine was never sold in Russia but some got imported. Although hard to tell if the injector is going to suddenly get worse or not, and whether cylinder 4 is going to suffer from running too lean or if I'm risking damage to the bore (from fuel washing), cat or pre-cat lambda sensor from 1 running rich. BMW ownership is a new level of fun.

Edited October 14, 2023 by JumpingFrog

[JohnD]

15km/hr!  As much as that!  In London it's sometimes less than 10!

(I'm told! )

[Nick Jones]

High level diagnosing going on there.
 

Can’t fault your logic. The difference in trims tells the story really. I guess if you were feeling brave (daft?) you could move no. 1 injector to 2 or 3 and maybe prove your theory, but not especially easy and risks screwing it up worse…… 

Plugs actually look pretty good. I wouldn’t judge that you are yet at risk from bore washing on #1. Lean related problems on 4 perhaps more of a risk. Though injector leakage typically causes more problems at low load because the leakage is larger relative to the required flow.

[RogerH]

What language is David speaking.????

 

Roger

[Nick Jones]

3 hours ago, RogerH said:

What language is David speaking.????

Modern car diagnostics, BMW dialect. 
 

It’s horribly complex and, frankly, goes well over the heads of about 85% of “automotive technicians” including those in franchised dealers. Consequently the “parts cannon” approach is frequently applied with catastrophic results on the owner’s wallet…..

[JumpingFrog]

Hmm, well I was planning to hunt down new injectors and change both on bank 1, I've even bought an injector puller. But after a week of research, it seems like I'm better leaving it alone. Again, this engine is ridiculously complicated. I mentioned before the NOx sensor is very dead, without this I already knew these cars get 15-20% worse fuel consumption since it's locked to "simple" homogeneous injection mode. I was getting low to mid 40's on the motorway in Europe when it should do over 50mpg.

However, more research suggests without the stratified charge mode, the ECU also disables the adjustment/adaptation of long term fuel trims, depending on how long it has been broken (I suspect years) and how the injectors have aged, this can lead to significant roughness. Mine isn't that bad yet. There is some theory that the ECU needs stratified charge mode to work so that it can measure the efficiency of the injectors (including leakage info).

This blog is basically the only source of information on the web, it's quite opinionated but interesting nonetheless:

• https://bimmerprofs.com/noxem-130/
• https://bimmerprofs.com/direct-injection-stratified-charge/
• https://bimmerprofs.com/uneven-operation-trim-errors-rough-idle-hidden-cause/
• https://bimmerprofs.com/stratified-charge-important/

Obviously they also sell the sensor emulator I've bought, so I'm taking the doom-mongering with a dose of scepticism, especially when something seems like the magic solution to all your problems. But reviews largely suggest that they're correct and it is worth it. They also suggest that this lean trim code is usually caused by out of date long term fuel trim data:

• https://bimmerprofs.com/typical-situation-case-damage-nox-sensor/
• https://bimmerprofs.com/virtual-probe-part-2/

 

On 10/15/2023 at 12:06 AM, Nick Jones said:

Can’t fault your logic. The difference in trims tells the story really. I guess if you were feeling brave (daft?) you could move no. 1 injector to 2 or 3 and maybe prove your theory, but not especially easy and risks screwing it up worse…… 

Plugs actually look pretty good. I wouldn’t judge that you are yet at risk from bore washing on #1. Lean related problems on 4 perhaps more of a risk. Though injector leakage typically causes more problems at low load because the leakage is larger relative to the required flow.

I'm relatively satisfied that in its current state it's not running significantly rich or lean and I don't see any issues with the lambda probes, but I'll try the test mode for them in the ECU this weekend. Since the engine is designed for lean running anyway, I guess damage from lean running would be ironic? But 2500 miles is still a long way...

On 10/14/2023 at 8:33 PM, JohnD said:

15km/hr!  As much as that!  In London it's sometimes less than 10!

Hmm, I think worse place I've ever driven for traffic is Tehran, that just felt like the heist traffic jam scene from the Italian Job. Moscow is second - very car-centred design, but too much traffic. As for London I'm avoiding driving in it, train is too convenient. So far I'm convinced driving in Moscow is largely pointless unless you have stuff to move, even with fuel at 60p a litre, it's not worth it.

On 10/15/2023 at 12:18 PM, RogerH said:

What language is David speaking.????

The more I read about modern BMW engines, the more I think that it's a miracle they work at all. Will be glad to work on simpler cars once again... Triumphs are a positive delight.

Extra Information:
So here is how the data looks about 30-60 seconds after cold start (+5c ambient):

And then after about 10 minutes, when both lambda sensors are up to temperature, everything settles down and looks much more even between banks:

I forgot to translate them, but the idea is clear enough. It's fun that for injector specific values they follow 6-cylinder firing order such that 1=1, 3=4, 5=4 and 6=3.

Can still see ECU doing things I don't expect, appears to be increasing fuel in cylinder 1 and reducing it in cylinder 4 when cold. Which suggests to me it didn't know about the leak when the NOx sensor went bad. But it stops doing that when warm and starts enriching 4 more than 1. But all this is for idle, and how its behaving under load I'm yet to find out.

Edited October 19, 2023 by JumpingFrog

[Nick Jones]

51 minutes ago, JumpingFrog said:

The more I read about modern BMW engines, the more I think that it's a miracle they work at all

 I don’t think you are alone there.  Trouble is, it’s an imperfect miracle as quite a lot of them don’t work as intended.

Mind you, BMW are not alone either as I don’t think VAG product is much better. Maybe even worse. And they have the randomly self-dismantling valve gear (roller rockers that fall apart, sometimes at quite low mileages) to contend with as well.

[RogerH]

[Nick Jones]

Quite….. maybe electric isn’t so bad….

[JumpingFrog]

Well, I don't seem to be actually managing to fix anything, car is up to its waist in snow, mostly just busy with bureaucracy at the moment. Don't believe anyone who tells you the UK gives away visas to anyone who can spell their own name, it's not true.

Some delivery van also managed to hit it while parking (I don't understand either), not very pleased, there is some damage. On the plus side, I now own a snow shovel...

I'm scared of the battery going flat so I'm starting it every other week and running to temperature. Actually it's starting pretty well, the roughness at cold idle is almost unnoticeable now. Saw some talk online of a good test for leaking injectors being observing rail pressure after engine off, my car passes that test, maintaining 150 bar. So leaving it definitely seems the best option, fires up easily even at -10c.

Also found out that the ambient temperature sensor reading seems to stop at -20c, didn't register the -26c we got a few weeks ago.

But a new problem has surfaced, now the ECU complains about low oil pressure on cold start up. It's very odd, doesn't illuminate any lights, and watching the sensor data it's easily making pressure up to 100psi... Oil is already "winter grade", 0w30 and it's decent stuff too. Not burnt any, no blue smoke, no rattling, I was pushing it quite hard at times through Germany and Poland and had no issues.

So I'm going to replace the oil pressure regulation valve (albeit used, since new is 4x the UK price) and sensor (new, was only 2x the UK price) to be sure. Also been recommended elsewhere to drop the sump and look for pieces of the timing chain guides... Sounds like a good idea, but dropping the sump is a pig of a job. You have to drop the subframe for clearance, but the engine also sits on that subframe... I'd pay a garage to do it, but I want to see what's going on in there for myself, so hopefully I can rent a garage for the day instead.

Will probably also end up doing the timing chain once I'm back in the UK and can actually get decent parts without selling kidneys and using grey market websites to import from Poland. It doesn't seem that slack... Kind of glad I drove a Triumph to Mongolia and not something like this, at least our biggest worry then was only disintegrating driveshafts and suspension bushes, and not the engine internally disintegrating and starving itself of oil.

Edited January 15, 2024 by JumpingFrog

[Nick Jones]

9 hours ago, JumpingFrog said:

Don't believe anyone who tells you the UK gives away visas to anyone who can spell their own name, it's not true.

Oh, I don’t. Home office / immigration service mostly does procrastination,  incompetence and performative cruelty at present. Good luck with that venture. Had always thought you were native actually.

As for the BMW…. If the ECU is actually reading 100 psi….. is that really inadequate?!  Can you (relatively easily!) fit a mechanical gauge and sanity check it? 
 

Had similar (in a far less sophisticated Seat Arosa) when the bloody car suddenly started beeping and flashing warning lights claiming low oil pressure. Engine seemed well enough and a mechanical gauge showed pressure to be in range. I could not unravel the electrical issue - everything I could test worked as expected and yet the warnings persisted. And then it suddenly fixed itself….. Bloody cars!

As for that van…..

[JumpingFrog]

On 1/15/2024 at 11:16 PM, Nick Jones said:

Oh, I don’t. Home office / immigration service mostly does procrastination,  incompetence and performative cruelty at present. Good luck with that venture. Had always thought you were native actually.

I am British, but now I have a Russian wife... Long story short, during the pandemic in 2020 I got offered a chance to work in Russia temporarily, before everything hit the fan. Due to meeting my wife I couldn't just leave, but couldn't stay, spent the last few years working out what is the best thing to do.

The amount of hoops to jump though and the shear cost is frustrating, English language test in Armenia, tuberculosis tests, letters from past and present employers, title deeds for my parent's house, 80 separate pieces of evidence in the end. Anyway, I have most things sorted for relocation in April, but first my job is to transport all our stuff to England in aforementioned broken 3 series.

Back to the BMW. I don't know what's going on, I have some hunches, no particular order:

1. Sensor is on the way out and occasionally giving jittery readings, but behaves when oil gets warm?
2. Valve is sticky and isn't doing as commanded it's only a two wire thing and driven by PWM, so guessing ECU doesn't know the real position. ECU then gives up and just fully closes it?
3. Plastic chunks settled in sump, when oil is cold/thick they block the pickup to the oil pump. If it's this, it really needs fixing before the 2500 miles home.
4. Some combination of the 3.

Of course nobody knows exactly what the BMW ECU is doing, and while oil pressure problems with these engines are known, they're usually due to point 3 but happen only under load. Failures of the valve aren't unheard of though, but I can't find any description of how that manifests anywhere. The parts cannon method seems to be how the majority fix such issues, but doesn't help me really.

On 1/15/2024 at 11:16 PM, Nick Jones said:

As for the BMW…. If the ECU is actually reading 100 psi….. is that really inadequate?!  Can you (relatively easily!) fit a mechanical gauge and sanity check it? 

I agree a mechanical oil gauge is a good idea, but for the price of the gauge and fittings, I'd already be half way to just throwing a new sensor on it? Although I'll also be none the wiser.

 

Edited March 21, 2024 by JumpingFrog

[JumpingFrog]

Some more jobs done, first changed the oil filter housing gasket and oil thermostat gaskets. They had gone very hard in the winter and were leaking pretty badly, parts were cheap and easy to get and fit, so for extra challenge I did it in the snow.


After this, we left for a short trip to see the northern lights (alas not in my car)...


By the time I next started the car next a few weeks later, the weather was much warmer, problems with oil pressure had disappeared:

The ECU seems to be able to maintain it's preferred 2.6 bar idle pressure at all times, even with hot oil. Before the electronic valve was defenitely not being used as the pressure was temperature dependent and the BMW software showed the PWM signal was 0%. Although the system still confuses me, the pump is a variable displacement type, and the eccentricity is varied by oil pressure (e.g. a feedback loop), and this valve is then an electronically controlled relief valve to bleed off excess pressure.

Anyway, I was still very curious about the condition of the valve, and if there would be any plastic debris from chain guides on its mesh filters, relatively easy to get to, remove air filter and alternator:

Valve looked okay, no signs of plastic debris from chain guides, and it even came out without excessive persuasion or snapping in half (apparently very common). Grey dust is probably just from me rotating it in its bore to losen it up. I'm fairly sure this valve is on the pre-filter side, so to me the debris look minor for a 90k mile engine.

Replaced it with the used valve that I picked up, just to eliminate it as the source of the problem. Used valve also seems to behave fine, passes the system test - in which it automatically runs the engine at different speeds from 700 to 2000 rpm and asks for different oil pressures from 2.6 bar to 5 bar. The old valve also passed that test though, but only when the ECU decided to enable it.

Found a garage to rent by the hour for next week with the right tools, so I'll hopefully find out what lurks in the sump...

Edited April 3, 2024 by JumpingFrog

[Nick Jones]

Your dedication is impressive! 

[Escadrille Ecosse]

A not inconsiderable effort. Good result.

The oil pump arrangement seems almost willfully complicated when something as simple as a slightly more sophisticated relief valve would seem adequate.

I assume this is all as a consequence of the VVT - or at least the excuse.

[Nick Jones]

14 minutes ago, Escadrille Ecosse said:

The oil pump arrangement seems almost willfully complicated when something as simple as a slightly more sophisticated relief valve would seem adequate.

I assume this is all as a consequence of the VVT - or at least the excuse.

Lots of moderns have variable displacement oil pumps, though the methods used seem to vary quite widely. I supposed VVT could contribute to the maximum peak flow required, thus widening the span between maximum and minimum demand and increasing the potential wastefulness of a simple PRV….
 

To be fair, they mostly seem pretty reliable - they just suffer from having no oil to pump as it’s all escaped past the low tension oil control rings, clogged solid by extended service intervals.

[JumpingFrog]

Well, good news and bad news, good news is that the oil pressure mystery is solved. Bad news is it's scary. Rented a lift in a Russian backstreet garage today, removing the sump is not fun, and the whole job took just under 8 hours.

This is what greeted me in the sump after 4 hours of work, which seemed not ideal, but could be worse?


Then I removed the oil pickup, not looking good.

Then I cleaned out the oil pickup, it has a strainer half way up, and this is what was inside...


All I've done is clear the oil pickup and put it back together I can't get the tools or the parts easily to change the chain here, and I need to leave on Monday. Fingers crossed it holds in there for the next 3000 miles. Seems pretty obvious now that the oil pressure fault codes in cold weather are from the labyrinth being formed in the pickup tube which the cold oil can't easily flow through. So far no signs of bearing material in either the filter or the sump, touch wood.

[Nick Jones]

Wow…. Just as well you looked! I’m sure it will feel better for its enema.

The amount of plastic junk is disturbing.  How much guide left to support the chain….? Is there chain noise? Is there any possibility it’s previously had guides done and not been cleaned out?

May the force be with you!

[JumpingFrog]

No real chain noise, it seems like the hydraulic tensioner is able to take up the slack. Impossible to see how much of the guides are left without removing them unfortunately. This is how they look when new:

Forums suggest that the chains quite rarely jump, it's usually the lack of oil pressure that kills the engine first. It's amazing it was making good oil pressure with a blockage like that, pump was definitely working hard.

It's possible it's had a chain, but I don't think so. That said it's common for garages to do the chain without cleaning out the sump, as dropping the sump doubles the time the job takes.

[yorkshire_spam]

Fascinating stuff @JumpingFrog, I don't know how you cope with the stress!