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scarceller scarceller is offline
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Join Date: Oct 2006
Location: Southern MA
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Very likely the CAT is bad.

But the slightly high NOx could also be one or more faulty injectors. A lean running cyl can cause NOx to go up.

Then the O2 sensor sees the average O2 content from all 6 cyls, if one cyl is running very lean because of a clogged injector that will increase NOx and it will also cause the other 5 cyls to go slightly rich because the O2 sensor sees a slight lean condition because of the one lean cyl, the DME will then richen the other 5 cyls and then HC also goes up.

Usually if NOx is high HC is low, but the above explanation is something to think about. A faulty clogged injector could result in both NOx and HC going up.
1984 911 Carrera Cab M491 (Factory Wide Body)
1975 911S Targa (SOLD)
1964 356SC (SOLD)
1987 Ford Mustang LX 5.0 Convertible
Old 02-18-2019, 10:42 AM
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