Is it possible to clean the Catalytic Converter in my 1991 300E... if so which method is best... If not then just disregard..

hi evan, yes there are a few tricks, but things have to be right.
your fuel mixture HAS to be 14.7 to 1. when that is dialed in you can drive the car for 50 to 100 miles with higher rpm then normal. as in droping down one gear on the freeway. this heats up the cat that burns off build up in the cat.
mixture is very important!!!!!
second, which may be faster is to remove the power boster line and let it run lean for about 20 minuites. this shoud have the rpm about 2 thousand.
before you start get some tailpipe readings with the cat at normal temp. and post them here.
don't waist your time if your mixture is not correct.
one more thing, with the booster line off, some short squits with carb spray toward the 02 can help.
imho
rich

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88 300E White, sold 9-04
88 190E Black 2.3 sold
90 300CE White, Grey sold 12-24-04
92 400E White,Grey Sold 5-06
90 300CE 91K Signal Red,Black Sold 2007
1989 300CE Smoke silver,Tan Sold 1-08
1993 300E 3.2 M104 motor
1991 300CE White,Grey
1994 E420 beautiful car,gone to new home
1994 E320 Smoke an Parchment.Beautiful car

how do i achieve the 14.7 to 1 ratio??? and it has to be 50-100 miles? isnt that doing a job on the tranny when driving in the wrong gear for that long??

[QUOTE][i] second, which may be faster is to remove the power boster line and let it run lean for about 20 minuites. this shoud have the rpm about 2 thousand.
/[QUOTE]

Ridiculous!!! A vacuum leak will not alter the fuel-air ratio. Feedback from the O2 sensor will add fuel to maintain a stoichiometric ratio (14.7:1)unless the vacuum leak is so large that the system cannot correct.

Normal closed loop operation maintains stoichiometry under all but WOT conditions.

I know of no way to "clean" a catalytic converter, nor is it necessary. If the KE system is in proper working order and oil consumption is not excessive the converter never needs to be "cleaned". Very high oil consumption of an overly rich or overly lean mixture over extended mileage can mechanically or chemically damage the converter, and at that point, the only fix is to replace it.

Duke

Fiddling with the fuel/air ratio will do absolutely nothing to clean your catalytic converter. Fidling with vacuum leaks will do exactly the same.....nothing.
When a converter is shot, it is shot.
The only solution is replacement.
JackD

oddly enough #2 does work if the cat has been subject to over fueling. over rich mix that is now corrected. the 02 cannot keep up with a vacuum leak of this size.it also cleans up the 02 sensor. this i have seen work and also was learned from the smog classes i have taken.shooting the carb spray does more for the 02 than the cat. it is not a bad thing to do when your car has been running rich.not all cats go bad,but they get coated with too much fuel which shuts it down.most 02's do not have enough range to cover more than a small vacuum leak. not all cats are bad,they just shut down when the mix goes off by a few points.
15-1 ?
hey if it works one out of ten then its worth it.
i have seen gross polluters come back to life with like new results.
just my 2 cents
rich

__________________
88 300E White, sold 9-04
88 190E Black 2.3 sold
90 300CE White, Grey sold 12-24-04
92 400E White,Grey Sold 5-06
90 300CE 91K Signal Red,Black Sold 2007
1989 300CE Smoke silver,Tan Sold 1-08
1993 300E 3.2 M104 motor
1991 300CE White,Grey
1994 E420 beautiful car,gone to new home
1994 E320 Smoke an Parchment.Beautiful car

I have never done it on an MB, but I have done it many times on the older Domestic cars. Make them run lean at about 2000 RPM for a few min. This lean mixture is extreamly hot with extra o2 in it which helps the converter burn off soot from a too rich mixture.
Also I have fixed many "lazy" O2 sensors the same way. Just don't do both of the above things at the same time ie don't run a lean mixture for 50-100 mile drive. The converter could get so hot it melts. The drive sometimes will help if the car never gets out on the interstate.

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84 500 SEL (307,xxx miles)