Failed Emission Test (high HC) M272 E300
Out Of Control!!
Joined: Apr 2019
Posts: 11,958
Likes: 6,802
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
@Roth I don't mean to hijack thread either...
carboned plugs are from combusted oil that for sure bias your 125kMi old upstream lambda sensors.
Change these!
Ignition: (plugs, boots and coils) always in good repair is mandatory condition to help prevent misfires.
I would leave alone the downstreams O2's.
carboned plugs are from combusted oil that for sure bias your 125kMi old upstream lambda sensors.
Change these!
Ignition: (plugs, boots and coils) always in good repair is mandatory condition to help prevent misfires.
I would leave alone the downstreams O2's.
Last edited by CaliBenzDriver; Dec 13, 2024 at 06:12 PM.
Member
Joined: Nov 2024
Posts: 152
Likes: 43
From: New Jersey/Philly
2010 E350 Coupe
@Roth I don't mean to hijack thread either...
carboned plugs are from combusted oil that for sure bias your 125kMi old upstream lambda sensors.
Change these!
Ignition: (plugs, boots and coils) always in good repair is mandatory condition to help prevent misfires.
I would leave alone the downstreams O2's.
carboned plugs are from combusted oil that for sure bias your 125kMi old upstream lambda sensors.
Change these!
Ignition: (plugs, boots and coils) always in good repair is mandatory condition to help prevent misfires.
I would leave alone the downstreams O2's.
Now I must go back to upstream data, as unfortunately they are (relatively) new with perhaps 20-25k mi on them and 2 1/2 yrs or so. Still doesn't make them magical and beyond the realms of early failure of course. I did think I also caught them staying rich, but I suppose there was a bit of denial in that observation hahaha.
This was also before I evicted my leaking fuel injectors, so perhaps some raw fuel paired with plenty of idling in traffic sent them to an early grave (I hope, for my FCP warranty sake).
Newbie
Joined: Oct 2024
Posts: 1
Likes: 0
My 2010 E550 emission solution
Check your Mape sensor & hose & any other emission hoses!
So, my 2010 E300 M272 engine with 69,000 km on odometer just failed emission test, its has high HC. Max allowed is 200ppm, mine is 278ppm. It just recently most of the oil/liquid changed (engine oil, atf, coolant, brake fluid, power steering fluid etc), air filter checked and no CEL (my launch scanner also found no error). So what to do next then if scanner found no errors? it has also no idling or power delivery issues even at WOT. I always use RON98 fuel. (according to the manual the car only requires RON 95 but the availability is not so good in my city, 98 RON is much easier to get).
I plan to:
I plan to:
- change fuel filter
- clean/calibrate injectors
- clean intake, maf etc
- carbon clean
