Thank you for your reply, I realized I missed the tests in the tests tab as you mentioned. The relevant test seems to be the refrigerant circuit test which tests even oil level.
Unfortunately it requires the B14 Outside Temperature Sensor (NOT the "Outside Temperature" value) to be less than 104F and the moment I stop anywhere it starts going up towards 140-150F. So it doesn't move forward with the test citing requirements not satisfied.
One important thing to note though, in the actual values page, the B14 Outside Temperature Sensor (with a given value or -40F to 194F) AND just Outside temperature (no given value) are listed separately. When I see 147F for B14 Outside Temperature Sensor, the Outside Temperature is like 104F. Explanation below:
They both have explanations AND (see screenshots below) it says when coolant is more than 122F and vehicle is at a standstill and temperature is rising it freezes the outside temperature sensor value and uses that as the outside temperature until vehicle exceed 18.6mph. Basically when you stop, the sensor reading way higher obviously and the car just takes the temperature when it started rising as the outside temperature fixed and then resets when you are moving.
This is expected behaviour but I guess to run the refrigerant circuit test I need to do it with a cold engine with the car in a shade or after sunset I guess as that directly looks at the B14 sensor.
Asnwers to your questions:
- I have the the VXDIAG VCX PLUS (C6 DOIP, compatible with C5 and C4, works with my 2021 GLS 580 too) It is disguised as a Mercedes VCX but it uses the Allscanner VXDIAG software and has lifetime licenses so I believe it is the VXDIAG VCX PLUS.
- My subscription is to startek parts catalog, no passthru is used as you found out. Version 2023.06.
- Would DTS Monaco do the adaptation?
- I could try an older version for this 2014 car.
- Yes your xentry screens for my VIN are same as mine.

 

I KIND OF FIXED THIS CLOSE TO 100% One of those situations where I don't know how exactly but let me give the latest info, there are some very interesting details but overall it is control valve timing, I just can't figure out why and why most of the time it can't calibrate it but sometimes it can.
- As of my last message the chirp was in a pretty bad shape like car almost undrivable with AC on. Loud belt slips, longer compressor lock ups even with drive mode in Comfort and adaptations did not work.
- I also realized that the chirp also happened when the car was in Drive and crawling and a very slight tap in the throttle where the RPM doesn't even pass 1000 and car doesn't leap at all it was still chirping, making control valve timing incorrectness highly likely, again. While I didn't see the tensioner moving from within the car obviously but I don't think it would move much with that.
- I had an assistant try to obliterate engine mounts to hell and the most it moved was like less than half an inch so it was normal.
- I got a temprorary Launch X431 diagnostic machine with Smartlink C v2.0 so it can flash control units. Thanks to chinese bs that device is NOT capable of flashing anything because first you have to somehow find out that you need to edit the file system of the android tablet to change an .ini file to enable flash menus, and then the smartlink vci device keeps saying function unsupported or expired which is supposedly a remote diagnostic thing and even if you do it offline it still says files could not be downloaded, then the manufacturer says you cannot do it in the USA. Apparently it was resticted, then unrestricted and then restricted in April 2025 again. So much for a $1500 device.
- I then used DTS Monaco 8.16, my original AC control unit software was from 2012 and Front Sam software was from 2013. I was able to barely find an updated file for the AC which killed the MaxCool button (not just because of the variant coding loss, I had backup) but also didn't fix the issue. The Front Sam was the latest I could find and just reflashed it on top of it. At this point getting a temprorary online coding license from Mercedes wouldn't even make sense as there is no guarantee online Daimler servers would have any updated software for those modules or whether they would fix it.
- Reverting variant coding and allvehicle configs didn't fix the MaxCool button and I just flashed the original software back, restored Variant codings and did the Workshop config (which can't be restored automatically) such as Belt Type: M278 (same as M157) etc and then did a adaptation again and GUESS WHAT, it is almost perfect now. I can rev the hell out of the engine at idle with A/C at max, do upshifts in full boost at mid-rpm, drive with sport+ and there is almost never any chirping. The most I can do is Sport+ hard acceleration very little chirping that I don't think anyone else beside me would hear. It was never this good before and for the past two weeks or so, non of the adaptations fixed it. I'll take it and leave it like this and watch how it goes. While this mostly confirms the control valve timing issue, it doesn't explain, why it broke (let's assume it was mechanical and I fixed it), why it doesn't do adaptation well, why it is not 100% perfect, it is now important to see whether the behavior is going to change without touching it. (I don't believe so) Technically I don't know how the adaption worked again. (Previously only worked once and this time even better)
- BTW I made the mistake of going to a "reputable" car A/C dedicated shop which had multiple $10K+ SnapOn machines but the knowledge didn't come with them (It was before I fixed it). My reasoning was to double check that oil level, refrigerant level, blockage possibility are OK despite me confirming them myself. Well, the guy connected the most recent SnapOn machine, which started recovery, and the machine stopped midway and said Tank Full. It did NOT show how much refrigerant or oil it recovered and there was no visual oil drain thank because it was such a state of the art machine and the guy didn't enter license tag so the machine didn't log it either. So he connected a second SnapOn machine, slightly older but still very professional, assuring me they are calibrated frequently. The machine extracted only 300gr refrigerant (Supposed to be 550) and said 0.0oz oil extracted! I told him there is no way the A/C would work with half the refrigerant and there is no way it would extract 0 ounces oil. He told me some explanations that I didn't care but at least offered to recharge the system 550gr and evacuate back and see. That machine DID have a drain container at the front and it had precise marks on it. He said no oil came out of it visually. This time we drained the oil container and then 550gr was charged and then evacuated and the machine said 470gr refrigerant evacuated and 0.0oz oil came out BUT the container had 30ml of oil in it! (Quarter of the whole capacity) I asked him why the machine is underreporting the refrigerant and why is it constantly saying 0.0oz oil? He had no proper answer. I told him that I don't trust that $19K machine anymore and he basically "made" the first machine workable for just once and just vacuumed the system (as the other one already evacuated) and we started calculating how much oil to put back! Decided to put back 30ml and did. I had a photo of the machine's LCD display. I then REALIZED THAT the second machine DID NOT HAVE THE FUNCTION TO MEASURE THE EXTRACTED OIL, it was saying 0.0oz because it was asking the TECHNICIAN TO INPUT THAT TO DISPLAY so the machine can add that much oil back! A huge mess as now we don't know if the system is correct on oil, and while there are no symptoms, the only way is to do a whole system flush but with the SL's condenser and expansion valve and the compressor it is a practical impossibility. At least I checked the pressures equalizing in 3-4 minutes after shut off, confirming no blockages or expansion valve etc issues. Also no compressor noise and no cooling problems. Still not sure on the oil level though but I have a spare compressor now I still believe itis fine btw.

 

Hopefully you've resolved this one. If I understand correctly, you basically reverted back to the original backup of the module and then had success? Something must have changed.

Your comment about the Launch X431 was timely for me. I was considering purchasing it to clone a module. I had already basically determined it couldn't do the job, but you confirmed it. Thanks.

My plan is to use DTS Monaco (I have v9) to do the cloning, but I'm still researching the steps involved. My immediate task will be cloning an ILS headlight control module. The biggest impediment to understanding DTS is translating all the German text. You obviously know DTS. Maybe we could start a new thread on it?

 

Sorry for the late reply, just been super busy but,
This has all the hallmarks of some software related issue for sure. Are you original owner? if not. did you get the VMI? Any history of electrical component replacement such as a SAM unit? In the end, its working and I believe it will probably get better as you drive the car. But that was pretty ugly for sure. Take the win...
This is why I thought there might be communication issue between the version of XENTRY or the Multipexer. As if though it wasn't either erasing the old adaptation (or it was unable to write the new adaptation over the old values). But XENTRY didn't check the adaptation and throw out an error in the software. It just kept working, as if though everything was being adapted propeerly. Probably how it was coded. It assumes everything is written properly and doesn't (or can't) run any kind of check. I've seen this behavior before with XENTRY before . It really seems like you reset everything to baseline, and re-ran the adaptation.

Lets see, I'm hoping it will get better over time, like most (normal) adaptations on these cars.
Unfortunately in situations like this, another tech will usually make things worse before it gets better. For diagnostic purposes, to figure out the exact culprit, this complicates things. We won't know if the original oil level could have played a part or the new oil level is playing a part in the improvement,..
Either way run it!

Good Luck

I have a guide for Vediamo which covers some basics. But can't attach it here as its larger than 20mb's (largest attachment size on MBworld
PM me your email if you don't have it and I can send it to you (it's 30mb)

I’ve been told that Vediamo works best for pre-facelift cars, but have no definitive information confirming this.

 

- No it isn't reverting back to original backup that fixed it.
- First of all, I am not saying it is 100% fixed. It is just the adaptation is now near perfect so it almost never does it anymore but I can still hear it just a little under the worst conditions for it. IT DOESN'T DO IT AT IDLE TO QUICK REVS ANYMORE EVER, that is a huge one. Not that I do revs to impress anyone but it was a way to test it. Also even under hard driving it doesn't do it %98 of the time, and if it does it is very little chirp and only if you have maxcool ac on because top is open. Previously it was a second-long chirp that ALWAYS happened.
- The first adaptation I ever did weeks ago was close to this one but any other adaptation was pretty bad almost undrivable. So this issue occurs for some let's say mechanical reason and the adaptation just doesn't properly work.
- The car also drives WAY smoother. So this is not just rev down, upshift thing. The car wasn't smooth while starting to accelerate and not even hard. (It was OK with AC off) This means the compressor is always a big load and ECU/Front SAM cleverly adjusts control valve pulsing to keep car smooth. The compressor adaptation and control valve pulsing is VERY important.
- What could possibly have changed is front SAM might have lost its possibly corrupt adaptation and did a better one, or maybe it justi got hard reset which can also be done standalone. Or, the flashing the AC module and restoring variant coding or even all vehicle DOES NOT restore the workshop codings. There is a setting named BELT TYPE: M272 M278 etc. No M157 but it is the same and originally it was M278. It got reset to M272 but I had trouble setting it back to M278 with the Launch tool (wasn't sticking) but eventually did it with Xentry.
- Important to note that I believe a little driving is also needed for adaptation.
- Not to rule out that the adaptation is dependent on some external sensors or stuff but some are off in my car but not at error throwing levels, so I needed to get lucky under conditions while doing adaptation. This time it was 2am.
- Of course I will be observing it but in experience it didn't change randomly before.
- IMPORTANT: Maybe this is why when modules like front sam got changed and problems like this go away. As an IT guy of 25 years of experience + electronics it could be as simple as a memory chip that has a failed address and adaptation data ending up there or not.
- As for X431, I beleive it CAN do module swap because it is able to copy an old module to new one. That doesn't require online access. IMPORTANT: Not all X431 devices come with Smartlink C, (the red VCI with display) that is a MUST. Also I hate the confusing names that they sell the same device in different markets in different names but they are the same. For example I got Pro3S+ Elite and a Pro V+ Elite arrived but they are the same. There is so many confusion on this. DON'T BUY ANY X431 THAT COMES WITH DBScar. It can't do any proper flashing despite how they present it.
- This has been a very hard to read thread, would be difficult. I ADVISE PEOPLE TO GET A SUMMARY FROM AI if they are in the same problem.
- IF I HAVE ANY ISSUES AGAIN, I WILL REPLACE BOTH FRONT SAM AND AC MODULE.
- I would suggest DTS Monaco 8.16 instead of 9.xx.
- Use a temprorary workspace with DTS Monaco and you will get English. (For programming)

 

Damn it, it's back. Might be conditions changing and not matching the adaptation anymore or it won't do it before I drove this much.
I will replace ac module and front sam and see how it goes and report here. I will also report if it doesn't do in some conditions with the current adaptation.
Also forgot to mention that I had tried doing the adaptation from old xentry, new xentry, Launch tool, they just request to get it done, car does it in 90 seconds.

 

It's still way better while driving though.

 

I have ordered Front SAM, AC Control unit AND Alternator Pulley because it was cheap aftermarket for testing and easy to swap.
I previously had tested the alternator pulley and it was OK but what if it is not ok all the time and it looks OK without alternator load and belt on it? $35 aftermarket and big space infront of it and I have the tool (basically a long T50 torx/star) This engine has too tight tolerances and regular one-way clutch testing might possibly not be enough. (hopefully)
I am leaning towards the scenario where there is an intermittent mechanical issue and the calibration is a hit or miss but eventually always a miss. Front SAM and AC Control unit are pretty easy to swap as well and I have the means to do control unit swaps
I will report back.
Maybe this is a rare occurence today but as R231s get older, it might be valueable information. Since the thread is basically a wall of text, I would update my first post if I ever fix this.

 

Keep us posted, at this point my money would be on the AC controller. Assuming you check/tested front SAM with XENTRY when the AC gets loaded? I would be surprised if it’s the front SAM (but nothing is impossible at this stage)

Sorry man, nothing worse than a job that just won’t go a way.

Good Luck.

 

WIS says AC controller doesn't control the compressor. It requests from the front sam which makes the decisions also taking into account other control unit requests and other sensor data on the bus.
as of now, although it checked out when I tested the one-way clutch of alternator and it was fine but now I am leaning maybe it is not fine under some tight conditions and also it messes up the compressor calibration. Parts areiving in a few days. Will do alternator pulley first.
Note: Initial cause doesn't have to be alternator. Belt slap that hard can wear it very quickly while I was fixing water pump and such.

 

It appears that alternator clutch pulley test is not just a one way freespin one way lock. There is some extended testing like spring feel existence and some newton meters torque to overrun direction and such. (The devil hides in the details) I understand that with many engines it doesn't matter much but for M157 it does.
The part is out for delivery and it is a 10 minute job with the right tool. Luckily nothing needs to be removed for this job and it can be done from the top. Fingers crossed.

 

FINALLY FULLY FIXED!
I replaced the alternator pulley many thanks to crashmaster (even after it initially checking out ok, I replaced it as a last resort) and it is fully fixed. Not the slightest chirp. Didn't even need to do adaptation again. WIS alternator pulley removal documentation says something about replacing the pulley at 100.000km/~60.000 miles. I am not speaking early this time. Driven enough to see it fully gone before posting. Didn't replace front SAM and or AC control unit.
Again the car has become crazy smooth. Alternator steals 15-30Nm from the engine and around idle stop start traffic it is a very significant amount close to idle.
LESSONS LEARNED THAT APPLY TO M157:
- Don't trust a simple alternator pulley clutch directionality locking test with this engine. Many others (even the most similar M278) will work ok with slightly worn alternator pulleys but not M157. Do a through test (like springy feeling, some torque to be applied etc) or just damn replace it at 60.000 miles. It is easy with the right tools. Nothing needs to be removed and there is plenty of space. The only issue I had was the pulley had slap-tightened itself so I had to use a freeze action penetrating oil to remove it. Also while tightening it back to 75Nm I needed to use a crowfeet adapter as my torque wrench was one way clicking. And some bad tolerance tools had slippage. Other than that you can do it from the top.
- An uneven load on the alternator causes the compressor to lock up and also messes with the adaptation on this clutchless M157.
- Always check your water pump pulley, whether it walked outwards. That could be the start of it.
- IMPORTANT: We can't surely say this started with the alternator, but it ended with it. Such hard slaps kill a lot of parts. Water pump walked out, belt got trashed twice.

 

Since the replacement pulley I put was chinese (for testing) I was going for Febi Bilstein as it fixed the issue and I realized AutoHauz had clearance INA for $30! OEM Mercedes is $300 and guess what, they are exactly the same. See below. (INA is the OEM manufacturer for Mercedes pulleys and bearings) Now I don't have the fear of chinese pulley failing in 6 months as with 3.1:1 ratio it spins almost 20.000RPM.