Mercedese632014

Hi All
First post about my much loved e63 AMG estate from 2014 -
I have searched hard all the forums and no luck with anything that seems to hit the mark in terms of issues that I have currently with the car.

First thing I noticed was the engine light (orange) which came on then and after a long drive switched off so mercedes thought it might be emissions issue. Mercedes have now had the car for 3 weeks and after calling in the diagnostic people think I have an irregular injector spray caused by bad fuel - the remedy would be flush the whole system and run new fuel and do a reset on the light! My concern is that they had the car and came up with so many different options that I dont want to spend close to 2K on flushing when I am not convinced this will resolve the problem. I believe the code was a mis fire code and generally on start up or within the first 1 min of running the car.
The organge light is now on all the time and needs to be switched off with the computer

Since the above recommendation I have had the car fully serviced and new plugs were installed as per the service requirements.
The company that did the work said the car was running very rough when cold for the first 1 min and then was perfect to drive when getting warm - he said that he believed that a flush of the system was not required and felt but not sure that it could be the MASS AIR flow sensor that is playing up!

I am starting to get concerned with mercedes that I will shell out cash for them to trouble shoot a problem that they are not totally sure is an issue! They have said that they were stumped with the issue

Does anyone have any experience of this issue - The light once switch off normally comes on as soon as you power away from the garage (circa 1-5 mins after the reset) normally from cold.

goodmaj

Here's a shot in the dark, I haven't seen any MAF issues with my car but saw them aplenty with my M5. The easiest test to see if your MAFs are at issue is to simply disconnect them and then start it up. If you're seeing the same results in both cases, the MAFs aren't the problem.

Based on what you describe, I'd have a hard time seeing this as a MAF issue. If it consistently ran rough no matter the temperature, then maybe. It'd be interesting to hook up a code reader to see the code(s) behind the CEL. Emissions does seem like a possible, stress possible solution since the problem seems to go away after the car is warm. Have they checked the pre- and post-cat O2 sensors?

Mercedese632014

Thanks for the quick response and help! I agree with your comments hence why I was quite baffled when the mechanic mentioned this!
Interestingly I did get a message from the dealer around the fault and they said it was linked to "irregular injector spray"
What was strange it took them 3 weeks to get to that point which makes me think it was not a straight forward code but one they had to dig through other possibilities to get to this. this is why they mentioned a system flush

Thanks for your comments much appreciated

I will do the disconnect and see where that gets me - I presume the plugs that go straight in to the air box? for the MAF sensor

goodmaj

They'll be on the intake hoses. I still think it's not the MAFs because the car is good when warm. "Irregular injector spray" seems like a very remote possibility at best, once again because the car is good when warm. The key piece of information here is you only get a CEL along with the rough engine when it's cold, but when the engine is warm, things are great. Another test would be to clear the CEL after it warms up and then restart when warm. If no CEL and the engine runs well, then you need to look for things that are different when cold vs. warm, which is why the O2 sensors would probably be my first stop, but ideally I'd first want to pull the code that gets fired when cold (clear the old codes first).

goodmaj

And, in fairness to your shop, if the problem only happens when the engine is cold, you need to obviously wait under it's cold again before testing something else, which may help explain the three weeks, or at least part of them.

Savage212

The M157 engine does not appear to have a MAF.

goodmaj

For the life of me I've been trying to find the MAF locations for the M157 to help out but every search came up dry. Definitely not the MAFs!

Mercedese632014

ok all!
Just plugged my OBD reader in and two codes coming up!
P2179
System too lean Off idle bank 1
and P2177
System too lean off idle bank 2

Goodmaj this could point to O2 sensors as you mentioned and given no MAF on this engine which mercedes have also confirmed seems to point towards your theory -

Just wondered if you thought this might be the case now I have confirmed codes
I have done a reset and will see tomorrow when I drive when the light comes back on and take a reading again!

Many thanks

Nick

goodmaj

Here's a related thread....this person had much more going on than you and his engine has MAFs, but after a quick read through two things stood out that might be part(s) of your problem, vacuum leaks and O2 sensors. Before throwing parts at it, I'd have your shop check for leaks, and if no leaks, have them check the O2 sensors.

https://mbworld.org/forums/c63-amg-w...k-miles-3.html

Mercedese632014

Excellent and thanks for the response!
I will check my air filter seals first
And will report back