1993 F150, 4.9 Six, Manual Transmission.

I'm experiencing what looks to be excessive exhaust back pressure.

There are two "units" in my exhaust before the muffler.

Which one is the Cat Converter?

Go Farm Trucks.

 

Not sure why there are 2 units behind the muffler. Maybe there is a special emissions requirement in your area. Wish I could be more help, do both units look the same/similar or are there distinct differences? The cat is usually the closest to the engine on the exhaust. At least in a traditional set up with a cat and muffler.

 

Both devices make up the catalytic converter system


Later model vehicles are now using a single 3 way converter.

 

rla2005 is correct, they are both catalytic converters. IIRC the first one is for HC and CO. The second one, which I believe has the air tube going to it, is for NOx.

 

Well that's what I need to know! I guess at this point I'll try to measure pressure at the secondary air injection fitting between the two units, and see if its less or the same as what I had at the O2 sensor.

Here is a diagram I pulled.



1993 4.9L exhaust.

Thanks guys!