Emissions -Failed - PeachParts Mercedes-Benz Forum

RAN · #1 10-02-2007, 07:39 AM

Hi,

I have a ML230 European and 5 Emissions -Failed this year.
I already change O2 sensor, catalytic converter, spark plugs.
I spend much money replacing the components and for what?
I already send the car to mercedes and no one can tell me what the problem is

5 Emissions -Failed

Could you help me please?
Thank you in advance

mbdoc · #2 10-02-2007, 08:42 AM

Can you post the results? Are there any check engine codes?

Fuel pressure & air mass are responsible for 95% of the fuel mixture.

RAN · #3 10-02-2007, 10:00 AM

Hi,

I dont have check engine codes, only

Lambda sond > 1.03
CO Min.2000 RPM > 0.3%

Emission test failed.

Thank you for your great help

RAN · #4 10-03-2007, 04:02 AM

Any news?

RAN · #5 10-03-2007, 05:05 AM

With this values

Lambda sond > 1.03
CO Min.2000 RPM > 0.3%

Emission test failed.

Can be the MAF?

Thank you for your help

mbdoc · #6 10-03-2007, 08:08 AM

IF the engine reaches operating temps then....
Either the air mass sensor OR the O2 sensor is the most likely.

The O2 sensor tries to make up for a bad air mass sensor.

RAN · #7 10-03-2007, 08:12 AM

Do you think I have to buy a MAF?
More $$$

I already buy a O2 Lambda sensor

RAN · #8 10-04-2007, 06:52 AM

Hi,

New MAF

CO Min.2000 RPM > 0% - Its ok now
BUT
Lambda sond > betwen 1.06 and +/- 1.15 - Emission test failed again

I think is one thing its strange
When the throttle is on 4.000RPM and the car stoped the engine goes up and down. +/- 500RPM up and +/- 500RPM down. Its normal?

HELP ME PLEASE

DCF · #9 10-04-2007, 09:28 AM

Quote:

Originally Posted by RAN

Hi,

New MAF

CO Min.2000 RPM > 0% - Its ok now
BUT
Lambda sond > betwen 1.06 and +/- 1.15 - Emission test failed again

I think is one thing its strange
When the throttle is on 4.000RPM and the car stoped the engine goes up and down. +/- 500RPM up and +/- 500RPM down. Its normal?

HELP ME PLEASE

Have you checked for vacuum leaks? That can cause the RPM issue you described, and throw off the mixture.

RAN · #10 10-04-2007, 10:05 AM

Dear DCF

When you say vacuum leaks you refer exhaust ot intake manifold?
Can be the EGR valve to?

Exhaust manifold seems to be ok but Intake I dont know

Thank you for your great help

jfreezn · #11 10-06-2007, 05:00 PM

Quote:

Originally Posted by RAN

Hi,

New MAF

CO Min.2000 RPM > 0% - Its ok now
BUT
Lambda sond > betwen 1.06 and +/- 1.15 - Emission test failed again

I think is one thing its strange
When the throttle is on 4.000RPM and the car stoped the engine goes up and down. +/- 500RPM up and +/- 500RPM down. Its normal?

HELP ME PLEASE

That is normal

That is a engine speed limiter that kicks in, at 4000 RPM, only when you are in neutral or park

Jim in Phoenix