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Hi everyone. M274 2017 E300. I'm struggling here a bit. A few weeks ago I got a CEL (solid, not flashing). The code was reading that the bank 1 was running lean.
I drove about 400+ miles with the lean code on, never had any issues or felt the car or engine make any noise or run any different.
About 10 days ago I turned the car on and left the driveway, and the CEL came back on, car felt sluggish and didn't want to shift. I brought the car back to my house and parked it, haven't driven or turned it on for 10-12 days. I just went to turn it on just now and the engine was shaking and the CEL was flashing yellow. I let the car run for a little bit and the CEL stopped flashing, and the car ran okay for a 30-40 seconds until it started shaking again.
I got the below CEL codes:
Anyone got any ideas? I plan on doing the following tomorrow:
1. Swap the spark plugs from CYL 1 to CYL 2, and CYL 4 to CYL 3.
If that doesn't work I will:
2. Do the same with the coils.
If that doesn't work I will:
3. Swap the fuel injectors and check if that's the issue.
When was the last time you changed the spark plugs? Common issue with this engine, spark plugs need to be changed every 40K miles or so to prevent the misfires.
When was the last time you changed the spark plugs? Common issue with this engine, spark plugs need to be changed every 40K miles or so to prevent the misfires.
I carry out all my car service religiously at the exact mark or before it's supposed to be replaced. I believe the spark plugs were changed out 12,000 miles ago or so. I also checked CYL 1 spark plug when I first got the Lean Mixture CEL and confirmed it's not worn out or had any visual issues with it.
I do believe it could be a fuel delivery issue to the engine now since the issues just been getting worse and worse for a few weeks now. I'll probably have to check fuel pressure and everything today.
Took out the spark plugs. Theyre all black. Looks like the car was spraying more fuel than it should've. I don't understand how this is possible when the code before was saying it was running "lean" which should be more air, not fuel.
My first guess is the engine is running rich due to some sort of aftermarket modification.
Car has 0 modifications. I have replaced both Upstream and downstream O2 sensors with MB OEM ones. Still giving me a lean code but only when taking off from 0 mph up to 20 mph range. I can clear the code and drive on the highway for 3 hours and it does not come on.
A dirty or bad MAP sensor could also cause the engine to run rich. Try cleaning it with a MAF/MAP cleaner or if you have extensive diagnostic tools you may also be able to read the live data on the sensor.
A dirty or bad MAP sensor could also cause the engine to run rich. Try cleaning it with a MAF/MAP cleaner or if you have extensive diagnostic tools you may also be able to read the live data on the sensor.
I actually took apart everything on the outside of the engine (Every hose, vacuum hose, intake manifold, exhaust manifold with turbo, PCV crankcase breather system, high pressure fuel pump, etc).
I ordered every single line and sensor that I saw including the knock sensors and the crankshaft sensors on both sides. I got sick of spending money on what could or could not be the issue so I decided if im spending all this time and money I'll just re-do everything with new parts. I also felt some play in my turbo so I ordered a new one and waiting on that to come in.
I'm hoping replacing all sensors and re-torquing everything down to spec will resolve the issues.
I actually took apart everything on the outside of the engine (Every hose, vacuum hose, intake manifold, exhaust manifold with turbo, PCV crankcase breather system, high pressure fuel pump, etc).
I ordered every single line and sensor that I saw including the knock sensors and the crankshaft sensors on both sides. I got sick of spending money on what could or could not be the issue so I decided if im spending all this time and money I'll just re-do everything with new parts. I also felt some play in my turbo so I ordered a new one and waiting on that to come in.
I'm hoping replacing all sensors and re-torquing everything down to spec will resolve the issues.
That's one way to do it haha. Can't imagine what the total cost ended up being for all those new parts.
That's one way to do it haha. Can't imagine what the total cost ended up being for all those new parts.
So far it's up to $2,000 with the turbo. I found a new OEM Mercedes/IHI turbo for a steal, still packaged and sealed. Today I replaced the famous leaking high pressure rubber fuel hoses that lead up to the pump. All in all about $2,000.
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