I have an 87 300E wish 195k miles and I failed emissions in CT so I had to take it to a garage to figure out what the problem was even though I hate using garages. The HC limit is 220 PPM and I got 205 at cruise (pass) and 224 at idle (fail). The CO% limit is 1.2 and I got 4.45 at cruise and 3.4 at Idle (both fail). So the garage could not figure out what was wrong and that cost $144 so they did an injector flush which cost $112. They did tell me this may not fix it but after it was done they had me pick it up so I assumed it was fixed. When I took it for the retest I passed HC levels but failed CO with a 3.57 cruise and 1.62 idle. The shop did tell me that my exhaust temp going into cat was the same coming out which they say says not reaction is taking place as temp should go up coming out of CAT. So I was going to get a new Catalytic Converter and muffler and do the O2 sensor with the Bosch p/n - 13953 for the 1990 Ford Mustang V8 302 as shown in this forum:
https://mbworld.org/forums/showt...ghlight=exhaust
So will this fix the problem. The car has good power but does make some weird noises mainly what sounds like a lose heat shield when the car is in drive but not moving. The noise goes away if you rev it up a little even if holding the brake so the car doesn't move. It is coming from under the valve cover and is not a heat shield. Anyways what CAT and muffler should I buy? I was looking at these:
http://www.autopartswarehouse.com

1987 Mercedes Benz 300E
Catalytic Converter
Brand: DEC
Note: Direct Fit Catalytic Converter Unit
FITS SKU PRICE QTY
MB2212 $288.40

1987 Mercedes Benz 300E
Muffler
Brand: Bosal
Note: Direct Fit, Rear Muffler, New Muffler, Installs With Simple Hand Tools
FITS SKU PRICE QTY
BO278195 $214.26

Similar stuff at this website as well:
http://replacement.car-stuff.com

I usually buy from Autohauz but the CAT is $900 there!
Would this replacement exhaust be good enough? I can't afford anything performance and they say that they are OEM so??? Any help would be greatly appreciated as I want to order ASAP so I can get my CT plates.

 

for anyone that is interested I seem to be getting somwhere here:
http://www.mercedesforum.com/m_36986..._/tm.htm#37082

 

Before you buy the whole jazz, just replace the O2 sensor, it might already be the fix for. The muffler parts don't contribute to the emissions. So if they are ok, leave them in. The most important thing to do before the emission test is to get to engine to a stable temperature (80C+). Just run it for 20-30 miles on the highway and have the test done immediately. Go step by step, it's cheaper!

 

I failed emissions and make sure u go to ur parts store get a new oxygen sensor and on a warm day disconnect the aux fan use 91 or higher octane get the car nice and warm and get ready to do the emissions. I live in california so and i passed it on an 86 300e. so it should be easier for you.