Hello all,
I just finally signed up after lurking on these forums for a couple of years. Recently (August) I pulled the trigger on a E450 for my wife, getting her out of a BMW. Overall, we have been very happy with the car, and it has not gotten much use with the pandemic and all of that, and it currently has just 2,000 miles. One oddity since buying the car was the stop/start seemed very intermittent as compared to other cars I have had with it. Sometimes it would work as expected, other drives it wouldn't do it's thing at all. Some times I would detect a mild stumble when the car restarted at a light or stop sign, almost like a misfire. It would clear almost immediately. After a few months the inspection was due, so I dropped it off at a local place who has done other German servicing for me in the past. I got a call about 10 minutes after leaving the car from the tech that when he started it, it was misfiring quite a bit and the check engine light was on. It cleared after a restart, and based on the age of the vehicle, they recommended I take it directly to the local MB dealer. They kept the car for a couple of days, could find no codes, charged the battery over night, and attempted to recreate the condition. We chalked it up to low voltage due to the length of time the car sat. Fast forward a couple of months and we drove it to visit some family about 200 miles away. The car acted perfectly. After getting back home, and letting the car sit for about an hour, I hopped back in to go grab dinner, and the car started up with what felt like half the cylinders misfiring, and the CEL came on and stayed on. The following morning it went back to the dealer. They called me today to state they replaced an injector based on a borescope inspection, and will test drive the car to validate the fix. After reading here of issues with buy backs early on with the W213s and the AMG derivatives, I'm a bit concerned I am at the start of a long process - I would have hoped MB would have cleared the problem up this late in the production run. Should I be concerned they are replacing injectors and taking the top of the motor apart at only 2,000 miles?

 

Injectors are a sub-component. As such, they can fail independently of the engine they are attached to. It's rare. Quite rare. But it can happen. A bad injector doesn't warrant taking the top end of the engine apart - a borescope is pretty non-invasive in the sense they likely inserted it down the spark plug hole to take a look. Direct injection is pretty mature. MB has been using it for quite a long time and the M256 engine has been in use since 2017. I really think you just had a bad injector. Chalk it up to luck of the draw. Like getting a bad light bulb out of the box new. It can and does happen. I'd keep driving, and certainly put more miles on. I can understand how an early sub-component failure on a new vehicle can shake one's confidence but I haven't seen or experienced anything to indicate it is a wide spread problem or symptomatic of any larger an issue.

 

With misfires, one needs to determine whether its compression, ignition or fuel related... When it came time to do the fuel injector leak test, it must have failed when they inspected the cylinder, i.e. seeing fuel inside. New components fail... that's why warranties exist.

 

Sorry to hear. Agree with the above comments. The 2020 E450 has the M276 3.0L twin turbo V6, correct? This engine has been around for quite a while, for Mercedes and is robust as far as Mercedes engines go. Injector failures, while not impossible, don't come up much on this site.

 

Sounds like it was just a faulty injector from the factory. I'll bet with the new one you should be fine now for a long time. The 2018 AMGS did have have some issues and for those that had issues it was kinda a nightmare, thats one reason I got rid of mine. But the Twin Turbo 3.0 V6 is an entirely different beast and I have not had a ounce of trouble outta mine except the usual bent rims as the tires are really too low profile.