[W126 Coupe] Emissions question

[richard jaffe]

Dick,

I don't believe I've ever seen an O2 sensor anywhere in the exhaust stream on my car. Also, the cats were never OE on this car. They were added when the car came over during the heyday of the gray market.

Rich
  ----- Original Message ----- 
  From: Dick Spellman<mailto:spell.yy at verizon.net> 
  To: Mercedes Coupes Mailing Lists<mailto:mbcoupes at mbcoupes.com> 
  Sent: Friday, February 23, 2007 9:40 PM
  Subject: Re: [W126 Coupe] Emissions question


  Hi Rich:

  When was the O2 sensor last replaced?  Assuming the O2 has <100K miles, check the lambda and make a note of the value then lean the lambda down till she just runs  poorly and add a can of Emissions Pass followed by a 30 minute 'easy' highway run just before going to the test center.  Leave engine running the entire time from highway run to emissions test and see if she passes.  Assuming you pass, rich up the lambda until you are back to the original values for best performance. 

  More than 100K on the O2, time to replace it.  DO the Mustang O2 sensor (see archives)  for $37 and you should be good to go.

  No rattle on the cats?  If you can move the exhaust so as to hear the cats rattle then you may have fouled out the cats (typically from too much oil hitting them over time) where the heat is trapped and they turn more solid then porous leaving you with a rattle and poor cleaning of the exhaust gasses.   Poor cats will usually result in an exhaust restriction giving your poor running which you are not having!  So, I'd probably lean her up as mentioned and then restore best performance when emissions are passed.

  Also check  to see at what point your state has any cut-off on emissions values due to vehicle age.  That's how I get a pass on my 83.

  Dick

  richard jaffe wrote: 
    Hello All:

    The following are the test results of the emissions test performed this afternoon on my 85 Euro 500 SEC:

                   25/25 test                                                                  50/25 test

                          reading             allowed         result                 reading        allowed        result
    HC ppm             212                 137              Fail                    216             140             Fail
    CO %               1.86                 0.87             Fail                   1.85             0.79           Fail
    NOx ppm          1028                 956              Fail                   1036            1046           Pass
    RPM                1302                 2500 max                              1357            2500 max
    CO+CO2 %       15.5                  6.0 min                                 15.5             6.0 min

    The following items are new: 8 fuel injectors w/ air tubes, Beru spark plugs, Beru ignition wires, Distributor cap and rotor button, ICM and various vacuum hoses and vacuum connector, 1 can BG 44 intake system cleaner.

    The car now runs great. Just can't seem to satisfy the clean air nazis in this state. Is the mixture too rich?
    Any ideas how to rectify this situation? Oh yeah, the car does have catalytic converters.

    Rich Jaffe
    85 Euro 500 SEC 259K
    83 300 SD         192K
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