Voltage transformer is dead, well not completely, but close too

What are your thoughts on this?

I'd try to find what the two misfiring cylinders have in common they are sharing.

away on a trip for couple days...

local MB style

serious salt truck

Enjoy! Where are you? Russia or Siberia?

But what do they have in common?
It's not the lambda, those are per 3 cylinders. The drivers side (LHD) coil pack is new from Clark, so I don't think that it should be a cause of problems.

It had a very rough time starting this morning and when it fired I didn't think that the engine would keep itself running.
After that it went into limp mode again, running on 6 cylinders (I think), but I'm not sure which cylinders.

Something that might be worth noticing, I do not have the correct sparkplugs installed. I have sparkplugs installed with the same specs as the one I should install, but the electrode distance (how deep it goes into the ignition chamber) is 3mm instead of 4mm.
I haven't had any problems with the sparkplugs and they ran absolutely fine, until the coil pack stopped working

I think you best need to figure your source of limp mode before fealing with 2/12 Cyl. misfiring (transformer, coil, plug, lean mixture).

Limp mode is triggered by hard faults the ECU/TCU computers are programmed to not work with... when these two are upset all bets are off (don't worry about misfirings at that point).

So far nothing points to the root cause. Misfirings are a very mild issue.

Can you dig up other DTC faults? It may be something like CGW is upsetting ECU...



chilling in Reykjavik Iceland... hot spring fall

Wow! What a view! Enjoy Reykjavik!

I didn't check yet, but some strange things have been happening in and around my car. I always thought that the limp mode was caused by an ignition coil pack not being attached and/or a whole bank of cylinders not firing properly.
Last friday the TCU didn't have any fault codes at all. I will try to verify the CAN bus this friday, as I said some time ago, I did find some mouse drops on my air intake manifold.

I'll keep you updated!

Hooked it up to DAS yesterday, no new error codes or any strange things. I've had a couple of traffic jams yesterday and during the jam I made sure that the engine was not misfiring very hard.
I did this whilst I was getting of the highway and I gave it a little gas once I had some space. V12 power.

Nothing more to add, raw V12 power. Up until red line, raw V12 power.

So, I've been driving rather aggressively from that point until I was home.

I started my car this morning and it hesitated a damn lot during starting, after that, only raw V12 power and... clicking noises.
It might have just needed an italian tune-up, since it was driving on 6 cylinders for quite some time, but I'm not entirely sure at this point.
The issues have been coming and going. It might just be that the wiring harness got damaged due to oil seeping into the connectors, can I use brake cleaner without damaging any of the connections and the plastic connector's housing to clean that?

Please do listen do the noises that come from my engine (if you turn up your volume you can hear some definite clunking)
https://ufile.io/n2svwjf1

I'm a little worried that these are the #420's (A1371800115 or OVERPRESSURE VALVE CYLINDER CUT-OUT SYSTEM) on the image below. Since I can only assume that CSO kicks in at around that point.
I'll try and see if I can actuate those valves manually using DAS, with my engine off, only to hear if they make any noise when moving.
@BenzNinja @kraut56 @tusabes @Welwynnick
Any experience on manually actuating the CSO valves in the valve covers?

The engine was mostly happy, but started to misfire for a brief moment after a restart everything was fine.
Then on my drive to work, lots of smoke came out of the exhaust, during acceleration.

At this point I'm worried that the strange noise I'm hearing might just be a valve that is stuck in it's down position and slams against the pistion heads.
I've cleaned out the venturi of the PCV system, are there any PCV experts around for the M137?

EDIT: the left valve cover removed



Please note the dents on the gliding surface

The above means the engine can mechanically run well but the ECU has a hard time figuring a proper mixture:

• sometimes lean (misfire),
• black smoke accelerations (rich),
• hard to start (lean)

"Bent valves"... do a physical compression test or a relative quick test using an inductive probe to read cranking amps on scope.
This will save you working plugs in/out... or instead now maybe a good time to normalize your plugs back to new OEM spec.

LTFT:
compare long term fuel trims to help point the problem cylinders: lean/rich.

Pitted camshaft:
Shows the result of poor lubrication on soft metal... MB likes to drop oil pressure in leaking chain tensioners plus wornout bearings gaps... switch to a thicker oil grade!
Perhaps Ceratec snake-oil additive can help with dry lube.

I had a friend come over, who has taken many of these cars apart and he noticed that;

• there was indeed unburned fuel in the exhaust gasses
• despite all the actions that I had taken, I still have a vacuum leak somewhere
  • I've got a hole in my PCV pipe, so that might have something to do with it

I also measured the oil level and oh boi; it told me to fill it up by 1.5L. So, the car was definitely burning oil, again...
Burning 1.5L of oil in a single day, that is a lot of oil.

Also, during our diagnosis session, I started the car, which had hard troubles to start, more troubles than usual.
The moment it started to ran fine, ABC lifted, so our verdict is that the AC compressor might be running dry (despite the AC being turned off), as there is no refrigirant in the system due to an condenser leak.
The waterpump should still be good as the temperatures are where they should be.

Then I tested ZAS using DAS (lol) and the engine load increased to 67% when the left bank turned off, with the engine barely able to keep itself running, this again indicates that there is a load on the engine that is not supposed to be there.
Switching to de-activation and back to activation didn't sound strange or anything, so that works just fine.
The engine still pulls like a rocket, but doing that didn't solve the oil smoke problem.

I've ordered an compression tester and an endoscope; should I measure the cranking amps on the starter motor?
I will definitely consider buying new spark plugs and possibly try to sell the old ones.
They are the Bosch FR8SPP332 which should fit onto the M120 V12, so if anyone is interested, hit me up.
They have around 6000km on them

I do think the previous owner put 5w30 in it or something, I was already using 5w40 and I'll continue to do so. The engine was running fine and healthy on that oil.
When I had the valve cover removed I did some wiggling around on the chain and there was a little bit of play on the chain.

As a more permanent storage, I've reuploaded the video I uploaded above, together with the chain slack test video

I've got an update; the PCV tubing got stuck underneath te throttle body and got perforated.
That also concludes the vacuum leak, since the engine was pulling in air from that perforated piece of tubing, luckily it was before the oil cooler, so no overpressure situation occured.

Now the confusing part; in EPC, the layout of the tubing is as follows


Looking at @kraut56 's post (https://mbworld.org/forums/s-class-w...ml#post8189709)
The hoses are connected the other way around, looking at a picture taken from the back of the engine, the hoses are routed like @kraut56 's hoses are



Should I swap them?

The new breather hose forces me to swap them around, if the weather is good I'll try to get the car back running again this friday.
I still find it curious that I can't reach the Central Gateway control module through DAS, but that the Central Gateway is working (as everything connects through the central gateway)

Coming back to the original topic of this thread, I've received most of the components of the voltage transformer.
Still waiting on a few, but I'll do an upgrade of the thing very soon.
I'll post a complete list once I'm done.

Is there any interest in an upgrade kit?

"The new breather hose forces me to swap them around, if the weather is good I'll try to get the car back running again this friday."

>> I can't wait for you to get this fixed and your V12 factory smooth again!!


"I still find it curious that I can't reach the Central Gateway control module through DAS, but that the Central Gateway is working (as everything connects through the central gateway)".

>> CGW works with multiple different CAN's it messages across networks acting as a gateway. I can see your CAN-B working and CAN-D not...


"Coming back to the original topic of this thread, I've received most of the components of the voltage transformer. Still waiting on a few, but I'll do an upgrade of the thing very soon.
I'll post a complete list once I'm done"

>> Make sure to use quality low-ESR Capacitors not just "general purpose".


"Is there any interest in an upgrade kit?"

>> Providing any documention would be a nice gesture for the next soul facing this issue.

my 4 answers within text above>>😊

Me too!

What else works on the CAN-D network?

Are you sure it's not CAN-C (engine controls) and CAN-B (body controls)?

Great! I will! I just created my new YouTube Channel and I'll be doing loads of CL600 related things on that channel.
Starting with the ABC hydraulic hose coming from the pump.

I'll try to create a video on repairing the voltage transformer too!

I've installed the new hose and roller and the car seems to be running fine. I'm also running with ZAS disabled for the moment.

One thing, on a cold start the car starts to misfire right away, but after a restart the misfiring goes away

Well, the CEL cleared itself.
Upon cold start, I need to manually hold the RPMs at around 1400, at which the car runs excellent.
If I don't hold the RPMs at around that value, the ECU detects misfires and shuts down some cylinders.

I still need to hookup DAS, but I'm very curious to know your opinions

You've come a long way to that point!
Hat's off👍

I think now is a good time to "relearn idle mixture" to see where the work of your cylinders stand: rich vs. lean.

> Perhaps Mr. Pete can tell us how to reset the LTFT logic with DAS so it does not impact the engine STFT while relearning O2/Lambda outputs.

Should no one volunteer soon enough, here is my quick procedure:

1. Pull an engine sensor (EVAP) to cause a mild ECU fault.
2. This enables the "clear" option.
3. Clear your ECU fault!
4. Go ahead compare fresh LTFT....

Thanks CaliBenzDriver!
You've been a massive help to me!

I just did another logging session with the ODB scanner, the short fuel trims based on the lambda's are all over the shop




The first peak after startup is me holding the RPM's at aruond 1400 and as I've said, the car runs excellent the rest of the trip.

You're most welcomed. I guarantee you've done the important part to make your car great again.

The STFT show they are all tracking TOGETHER wich is what you want.

Now the interesting part would be LTFT numbers: - are they close together near zero -or rich to get more gas for a unmetered air?
You've got to analyze what your engine is doing.

These are LTFT readings from the same trip as the previous screenshot



The car started to misfire again, at the trip home. I don't have any readings of that trip though.

Will check the ABC hoses tomorrow and read out the ECU

STFT 8x collection

LTFT 2x pair....

Wait I am lost!
You have 8x STFT but only 2x LTFT - I don't get it, really?

We are trying to figure the cause of your intermittent misfirings (now and then/not all the time).

By comparing LTFT we should see how the engine cylinders are burning then focus on any trouble spots. All LTFT numbers need to track each other.

(when running rich you run the risk to melt your cats honeycomb - so take it a bit easy until fixed)

Well, there are indeed only two LTFT's
I just noticed that the ignition angle is way off

Could this be caused by incorrect sparkplugs?


The TWC heating and post enrichment where on at the moment of starting
I still have a vacuum leak coming from the back of the engine.

Now you can write your own work order:
- Install good sparkplugs
- fix vacuum leaks
- read individual O2/Lambda
- Evaluate Fuel-trims
- Scrutinize "MISFIRING.... " PID's
- Reseach crazy timing angle (-25°Cw)
-

> Crazy Ignition Timing:
The spark timing advance is a calculated value, it's obviously far out of Max spec of -15°.
A normal working advance is near -5° to -8°.

Something in the ECU logic might need a reset after the ignition work you did to start fresh from a good base value.
IgnitionTiming is based on CKP sensor but that signal is well scrutinized for integrity.

>CKP Jitter -> Misfiring data:
Now it makes sense you are getting severe misfirings when ECU is trying to calculate a good timing advance.
Graph all the different MISFIRING PIDS available to see if that information helps point to your non-contributing cylinders. It may be un-true data because ECU is borderline out of the "closed loop" trying to point CKP jitter.

When the CKP expected signal shifts around early/late then ECU tries to pinpoint one particular cylinder as "misfiring" causing CKP jitter.

ECU adjust the mixture and the timing to produce consistent O2 exhaust results. This uses a dynamic map of previous datapoints, that's what you need to reset!

>Misfiring causes:
A while back, I said misfirings are not only caused by bad ignition plugs or coils. It's also caused by lean mixtures and wrong timing that cause unreliable firings regardless of strong sparks.

> Catch-22 here:
Bad firings cause rich O2 output, causes lean mixture, causes bad firings!!
So you see the vicious cycle once bad firing gets involved, right?

The ECU injection software is the very best mojo of BOSCH PhD engineers. It is some of the smartest real-time software that can be designed. In other words, you can trust the ECU logic is working all its "best efforts" to ignite your cylinders properly.

> CAN VIPs > timing latencies:
We've seen how the ECU job is to computes the best mixture/timing combination for all engine situations (Old/new, Cold/hot, Idling/uphill, ...).

That takes a bunch of sensors data, Bosch software and some CPU processing power to run all the compiled code.
Now let me shade the light on something uncommon. Realize that when VIP peripheral modules (F-SAM, TCU, CAN-C,...) that are in relation with ECU are loaded with DTC's, the engine precise timings are affected. That introduces fuziness in precise timings and additional random misfirings.

This is not the top cause of misfires but a super interesting knowledge to have in mind. You can not get the best engine driveability performance without humming CAN VIP's... DTC's introduce timing jitter that affects power output by 5 to 20%.

> Architecture is jitter sensitive:
The nuget is you want to reduce all factors that can affect precise timings. DTC's possible in CAN peripherals. Everything CAN is actually daisy chain like dominos after all. Try not to ignore "insignificant" faults connected to the ECU logic. This quirk took me over 20Yrs to figure out.

Thanks again Cali, that is a lot of information to soak up.

I've done some research and on my car, you can't access the CGW via DAS. The can bus is functioning as it should.
Having said that, there are indeed a few DTC's here and there, but those are mostly on the CAN-B (body canbus)

I've ordered the proper sparkplugs for my car and when they arrive I'll install them.

ZAS has also been acting up lately, so I disabled it. I am wanting to enable it in the future, though it might need fixing.

The DTC's on the ECU remained the same, but I can't recall myself clearing them last friday.
This morning it ran like a tractor again, I'm assuming that only bank 1 was working properly. Until a restart when the car was warmed up, then it all went good again

I'm wondering if replacing the capacitors inside of some of the control modules, might make the car more stable.

I think you've made a giant lip in recognizing your engine sometimes runs with half cylinders off and a simple restart fixes that condition.

That's where someone familiar with this rig can lead you quickly towards a known fix. I'll help if I can contribute electronic tips.

> Focussed open mind:
You've got to stay focussed on a short list of priorities while keeping an open mind for important items.
I don't like the "shotgun fixing" approach! When way too many things are involved at once it becomes harder to diagnose evidence of what's wrong.

The least you upset a complex system, the more likely it will remain stable.
[Troubleshoot > Fix > Test] as few items as practical at one time.

> Dry caps:
Once you get back to stable operations, we can visit modules to upgrade marginal caps. Until then, being conservative is the best bet.
I am afraid if we loose any more cylinders, car won't start.
We can use a targeted approach starting with Rear-SAM and up. Engine bay ECU are pretty amazing assemblies because of environmental stressors (heat, humidity, vibrations).

​​​​​​> 50% Off:
Is it the case this V12 engine uses two ECU each in charge of a bank of 6 cylinders?
They must share synchronized work in a particular way that is not initializing well all the time for some odd reason -
You must learn to troubleshoot why half this engine remains napping....


> Ferrari 308GT... half V8:
Year ago I installed an ignition kit to convert ignition points over to electronic. Everything on these V8 engines was duplicated: twin dual-barrel carburators, dual distributors...
Car was working great for a while but one day power felt a bit low... half the ignition had quit!

I can relate to how missing half of some engines is not always obvious when they stay balanced.