Eliminating Myths About Aftermarket Converters
I installed a new aftermarket converter, and a few days later
the customer returned complaining of sluggish performance.
When I looked at the converter, the "brick" was
melted and plugged. What's wrong with the aftermarket converter?"
Answer: The vehicle destroyed the converter due to engine
malfunction. A converter that has a melted substrate has
experienced temperatures in excess of 2000 degrees F (1200
C). A converter typically will not exceed 1000 degrees F
(600 C) when installed on a properly operating vehicle. It
is necessary to repair the engine malfunction before replacing
the converter. Otherwise, the new converter will melt too.
Common causes of melted converters include:
1. Three-way plus air vehicle running rich—when the
air is injected in the converter, the rear brick melts because
the excessive fuel now has enough oxygen to burn in the converter.
2. Vehicle running rich with exhaust pipe leak—air
is drawn into the exhaust pipe, combines with the excessive
fuel and burns in the converter.
3. Vehicle misfire—air/fuel charge leaves the combustion
chamber without firing, travels through the exhaust pipe
and burns in the converter.
"I put an new aftermarket converter on a vehicle that
had failed for NOx on the state emission inspection test,
but when the vehicle was retested it failed again. I finally
put an O.E. converter on it and it passed. What's wrong with
the aftermarket converter?"
Answer: There's nothing wrong with the aftermarket converter
- it was simply installed on a vehicle with a severe NOx
problem caused by one or more upstream mechanical issues.
The O.E. unit passed the test, but had NOx levels that were
still much higher than they should have been with a brand
new OE converter installed. The reason that the OE converter
performed better than the aftermarket converter is because
the OE converter is designed to last 80,000 miles and the
aftermarket converter is designed to last 25,000 miles. The
extra durability is achieved with extra catalyst. When the
converter is new, this extra catalyst increases the converter's
efficiency, but also increases the cost of the OE unit. The
root cause of the vehicle's NOx problem remains, however.
Standard aftermarket converters, by comparison, don't provide
that extra margin of safety in the form of added catalyst.
As a result, vehicles with upstream emissions issues, particularly
related to NOx, deserve special care when diagnosing the
vehicle because the most effective means of repair is to
correct the problem that is generating the excessive NOx
in the first place. In these cases, the most economical means
of repair may be a combination of engine repair and the installation
of a "Premium" aftermarket converter — such
as the new Clean Air Ultra universal converter. A "Premium" aftermarket
converter features increased catalyst similar to an OE converter,
without the high cost of an OE part.