View Single Post
Old 05-29-2004, 08:51 PM
stevebfl stevebfl is offline
Join Date: Mar 2000
Location: Gainesville FL
Posts: 6,844
Actually the catalyst could very easily be the right diagnosis. I'm not sure it would be wise to have service writers informed enough to understand the concept well enough to explain it. There probably aren't a lot of techs who do.

As a consumer it is probably easier to spot someone who can't make the story add up than to be able to understand it one's self.

Let me explain. A misfire is deduced by very quickly comparing the rotational acceleration rate of the crankshaft during its travels. It accelerates fastest after a firing and slows generally till the next firing. If now, you have a standing exhaust pulsewave bouncing back off a restrcited cat the acceleration rates are interupted and confused. The control unit misidentifies several cylinders as misfiring and then makes sure of it by turning off the fuel to those cylinders till the key is cycled.

And BTW the I would be real hesitant to put anything but a genuine MB cat on if that is the problem. The OBDII cars can tell the efficiency of the cat and the POS you can get for peanuts only works if tranporting the exhaust is the only criteria.
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician
Reply With Quote