RY zeek

cx876

have you check the engine mount ?

RY zeek

The motor doesn’t seem to be moving around too much I’ve had bad motor mounts in previous cars and I don’t feel any of those symptoms. What would that have to do with the hesitation and stumbling during acceleration? Thanks

EuroDriverSD

I'd suspect the MAF, the crank position sensor or the throttle body but best to get a STAR diagnostic done.

I had this happen once on my W211 after cleaning the throttle body & developed hard starts & stumbles that got progressively worse but no check engine. After throwing several parts at it to no avail, got it diagnosed and had to replace the throttle body

RY zeek

I was hoping it was not the two things you mentioned ! But also feared it at the same time! How much did it run you to get it diagnosed And fix thanks for the reply

EuroDriverSD

IIRC, it was somewhere between 1500-1800 all said and done
You can get the throttle body much cheaper online than at the dealer but it has to get programmed and in my case, they wouldn't do it if I sourced the TB elsewhere

RY zeek

Well that answered my next question because I planned to fix it myself but I assume it would have to be programmed . How much did just the diagnosis run you? And would you say the diagnosis would be how accurate? Thanks .

EuroDriverSD

An officialSTAR/Xentry diagnosis should run you between $100-150 and they are as good as it gets. A lot of things can't be diagnosed with universal scanners

atraudes

It would be worthwhile to get a generic scan from a parts store, just as a quick and easy check, no? If it shows something like "misfire on cylinder x" then you can look at that cylinder's plug, coil, wires, etc. just to rule the easy stuff out. If you still run into a brick wall, agreed, get a proper diagnosis.

Give all of the hoses connected to the intake a careful look over and make sure none are cracked or torn. Make sure the electrical connections going to things like the ignition coils and MAF are secure. Simple stuff, I know, but so many times it's something simple.

EuroDriverSD

If there's no check engine light, it's highly unlikely a generic scanner will yield any useful information.

RY zeek

I have checked everything obvious originally I had a check engine light ,a misfire I swapped coils around and change spark plugs to see if the misfire moved Cylinders. But the scan tool was no longer reading a misfire or any engine codes I have no check engine light ! The light went away problem used to go away after car was driven for 10 to 15 minutes. But now is there always at low RPM Struggling and hesitating. But does not seem to stumble when I have my foot hard on the throttle. . I was thinking maybe one of the fuel pumps . But still at this point I am looking for suggestions thanks

EuroDriverSD

These cars have very complicated electronics systems. We can make you feel good and give you guesses as to what the problem may be but the most likely result is that you will throw money at it with no relief. No one or nothing can give you a more accurate answer than a proper diagnosis.
Stop beating your head against a wall and get a STAR/Xentry diagnostic - you'll be amazed at what a thorough and detailed examination it does. My local shop waives the diagnostic fee if I have them perform the repairs; maybe you could ask yours to do the same.

RY zeek

Thank you yes at this point I agree that’s what it’s all leading back to ,I am looking into a place that can perform that for me . Not sure if it would be more effective if I got it done at a Mercedes dealer seeing how they obviously work on them consistently ,or if most any shop with the technology can perform it .? Thanks

RY zeek

Mostly I bring it up on here to see if someone suffered with the same problem the same exact symptoms and what was their end result. ?

baseme63amg

Hey man same problem here anyone ever fixed it ??

CaliBenzDriver

For reference read the above quote: Post #4

Post #1: starts with the MAF being out of question!

Assuming there are not CEL or related DTC to help speed up diagnostic:

This problem is when you can get $4k worth of repairs with nothing but an ECU reset + air filter ....

It's stumbling because of a seriously wrong mixture. It probably started with throttle lag and engine vibrations.

What maintenance items have been done vs. skipped over ?

>> Catch up with the basic maintenance items first then test for additional needs...

Can you see positive Fuel Trims indicating a lean engine with unmetered air:
- Camshaft rear covers
- PCV track
- Intake plenum seals ?
- Phasers?
-

I am not a fan of the bad "throttle body"... ECU scrutinize the plate feedback with top priority and triggers limp modes reliably.

> Can failed intake VVT phasers help produce that when they are rattling loose ?

cetialpha5

The real answer is to get a scanner that can do MB specific error codes. There are probably pending codes that don't show up with a regular generic scanner.

MgnML

[QUOTE=RY zeek;7978168]

CaliBenzDriver

Stumbling hard... what can the fuel supply tell us:

The longterm fuel trim number... highly positive?

The fuel pressure during acceleration... falling down ??

New in-tank filter else
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