1996 w202 2.8 not passing smog with no CEL
 

NEED SOME SERIOUS HELP!!!!!

OK checked everything...NO CEL code no nothing

MAS is fine and O2s are all fine (new o2 in the front)

no cracked intake man. cat is onky 2 yrs old

but the car is running rich on idle High CO and HC

it'll pass the 25k rpm test but failed big time on the idle (gross polluter)

2500 rpm
HC level at 127 (limit is 130)
CO level at 0.66 (limit is 1.00)

idle at 717 rpm
HC level at 371 (limit is 100)
CO level at 2.43 (limit is 1.00)

now after a can of 'guarantee to pass' fuel system treatment its doing better

25k rpm is doing way below limits
and CO would be at about 0.2-0.3
the HC would be at 0 after you drive it but once you let the car sit on idle for more than 2-3 mins the HC would creep back up to about 160

what could it be??

and also the OBDII readiness are not complete...so now i have drriven it in a few diff conditions

1. driven it 10 mins at 55mph
2. driven it 10 mins at 35 mph
3. idle with AC on for about 10 mins

havent re-cheked it since but what other drive cycles do i need to make sure that the OBDII readiness checks are completed??

Thanks A LOT!!!!!!

One cruicial component that's overlooked here is the catalytic converter.
Would be my bet. ;)

yeah but its a brand new OEM cat that i put in 2 yrs ago

and i have only put about 35,000 miles on them

It's hard to believe that the catalytic converter would fail for a 96 car unless the car has in-complete combustion problem. I have a gaser 91 735i with 170K miles and it recently passed CA emmission test with excellent results. Wife's 98 C280 passed with near zero emmission.

I wonder what is the reading before the CAT? If it is not right, better fix the source. Fuel system? Ignition system?

Pull the vac line off the fuel pressure regulator and see if there is any gas evident...

do you have a pict of that?? or where its located (ie which one is the vac line)

TIA

bump.....

The white arrow in this picture points to the fuel pressure regulator in a '96 C280. Pull the vacuum line and look for any gas.
Good Luck, Dan

thanks

checked and nope... no gas

i am gonna check the other vaccume lines tomorrow and the replace the plugs

what else should i be looking out for???

i am also gonna change the oil rite b4 i go in for the smog check (which should help lower the HC level)