M103 Maryland emissions fail!
 

Sigh. MD emissions failure, HC @ 195 out of an allowable 175. Damn it!

'93 190E 2.6 M103, ~167,500k.

car status:
-air filter about 2 years old with around 25k on it
-non-resistor Bosch plugs about 2 years old with around 25k on them
-fuel filter has about 25k on it
-plug wires, cap, rotor about 3 years old with around 30k
-catalytic converter original as far as I know
-fuel injectors original
-fresh oil change
-fresh valve stem seals
-brand new EGR valve
-recent O2 sensor replacement(I did the Bosch Mustang splice deal)
-all vac connectors that I could reasonably access have been replaced

I've had no luck finding a vacuum diagram for this car to find out if the EGR is routed correctly, so I have no idea. Car idles and runs very smoothly, but starts are a bit chokey sometimes. Fuel economy may be just a little off. Don't have a vacuum gauge in the cluster.

Does anyone have any suggestions on what I need to pass? Guy in the office said I was just a little over, by my calcs about 10%. I'd say that's significant.

Had you run it hard at freeway speeds for a while prior to taking it to have it tested?

Testing station is about 10 highway miles away, and I sat there idling before it was my turn long enough that the engine temp went up to the point where the visco fan engaged. I wouldn't say that I ran it hard on the way there. One more thing, tower screw has never been messed with either. I'm thinking the HC number means something is making the thing waste fuel. Would worn-out injectors be a likely suspect? It's either that or replace the cat. Engine runs smooth as glass and I don't really smell any unburned gasoline. EHA is dry. Runs great. But there is that coughing every other startup, and an almost imperceptible stumble every so often sitting at a traffic light.

It's a no-load idle & 2500rpm style test.

Love how those guys check your emissions equipment. They walk around your car carrying a mirror on a stick, but don't even look at it. They look away!

I have until April 4 2012 to rectify this situation.

So anyone have a vacuum diagram so I can check to see if my brand new $300 EGR valve is hooked up properly?

Post your emission numbers.

My M103 failed last year for high HC too. I barely failed at idle for that, everything else passed just fine including idle and high speed.

From memory, HC is unburned fuel. I attribute this due to my dire need of a valve job then.



I doubt the cat is bad on the car.

M103 (euro 300s) spark plugs are supposed to be replaced at 12k miles intervals. Yours are gapped correctly aren't they?
The air filter is clean isn't it?

The euro 300 I kept in Blighty (208k miles and original injectors, but no cat) passed its UK emissions test at 184 ppm HC and 0.134% CO, although it must be subject to a higher limit than yours. The CO is way too low, but was set by the test station. The HC didn't alter much though.
Presumably, your car passed its emissions previously, so, have you changed or had anything done to it since?

No I haven't changed anything. Barely passed emissions when I lived in DC, on the original faulty ignition parts no less. MD limits must be lower. Refer to my original post, it lists the car's current condition as it pertains to this issue.
I just ordered some plugs and an air filter as well as new injectors & seals. Going to pull the fuel dist & air meter and finally replace the air housing boot and the two molded idle air hoses I've had in the trunk for a couple of years now. The originals look OK but have hardened up and are no longer pliable. I've been meaning to do it but then I get to thinking 'car runs fine why bother' and of course I look at what I have to take off to get to those parts and it kills my motivation LOL. At least now since I have to pull all the hard lines to get the injectors replaced I'll have an easier time staying motivated.
I'm hoping new injectors & seals, air housing boot, and ICV hoses will get me where I need to be. Otherwise screw it I'll apply for a waiver LOL

BTW does anyone know if doing the R16/1 resistor removal trick(providing I can find the damned thing) will cause an increase in HC numbers? It advances the ignition from the stock 6 deg retard to 0. Supposedly it will increase fuel economy, and logic tells me an increase in fuel economy may in some way be a result of less unburned hydrocarbons flying out the tailpipe.

I have read that the best way you can do it is to run it hard (80mph) on the interstate for 20 to 30 minutes, pull into the station and have it tested as soon as you pull in.