tesna

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:

• change fuel filter
• clean/calibrate injectors
• clean intake, maf etc
• carbon clean

Any other suggestions? bad o2 sensor maybe? Or just simple thing like "italian" tune up aka spirited driving for a while. The car seldom revved, mostly driving in (bad) city traffic (but my other car with same traffic condition passed the test just fine hmmm)

S-Prihadi

Use your Launch screen graphing and see the oxygen sensors.
The 2 fronts are Wide Band, the 2 rears are simple Narrow Band 0 to 1 volt.

Find Lambda Value where 1.000 is perfect 14.7 to 1 AFR. Assuming your front oxygen sensors are healthy.
Lambda value changes with throttle input.

HC is unburned fuel.
My opinion is per 10 years you replaced all oxygen sensors if with Jakarta traffic jam, that is what I did for my E400 and the engine response became so much better.
While I do lots of redline RPM, you know Jakarta traffic is super snail speed and GDI engine ( mine ) is not the best for low load operation.


Your list for a 70,000 KM car of 14 years are good to do , as you listed in blue :
I plan to:

• change fuel filter ---- GOOD
• clean/calibrate injectors ---- WAIT FOR CAT CLEANING, or before CAT cleaning, up to you
• clean intake, maf etc ---- GOOD
• carbon clean ----- Elaborate on this carbon cleaning

Perhaps try this kind of service for your CAT too, because CAT is responsible too for minor reduction in HC.
Or do this first before all else and see the result.


When you use baby Launch, see if the wide band oxygen sensor you use is the older model with 2 Volts or newer one with very low milliamps value like my E400.
M271.8 EVO of C200 W204 of 2010 is still using older version wide-band oxygen sensor, the 2 volts one.





Have fun...........

streborx

When did you last change your spark plugs?

JettaRed

iTrader: (1)

I would start by checking fuel trims. The numbers represent percentages of fuel added or removed to reach lambda = 1. Negative values mean you are running rich. Ideally you want to stay between -10% and +10%. Values exceeding +/-25% will throw a CEL, so you could be at -20% and not have a CEL but would be running very rich.

If that's the case, try to discover why you are running rich. Dirty injectors could be a reason. Since I believe you have a non-GDI engine, new or remanufactured injectors should be relatively cheap and easy to install. There are companies that match and balance, as well as clean, your injectors. RC Fuel Injection is one, but I have no idea if they service Mercedes.

FCP has new injectors for around $80 each.