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

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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