Hey everyone.

I helping a friend build his 2007 FX4. Its obviously a 4x4 4.0L SOHC. He has just done catback 2.5" exhaust. In the future he is looking at JBA headers and a full 2" Y-piping into 2.5" exhaust. Once we lifted the truck I saw what a project it would be.

The issue I have is the 2x O2 sensors in the catalytic converters. It wouldn't be a problem if it were a 4x2, however in this case the front driveshaft completely limits space for a cat on the drivers side. He also has an RCD 5" suspension lift so that gets in the way as well.

I guess I'm looking for someone who has, or knows of someone whos done a full exhaust on a 4x4 before. Would repositioning the downflow O2 sensors "behind" magnaflow hiflow cats throw up a CEL?

 

I think the o2 sensors have to be a certain distance from the cats in order to work. The front o2 sensors read what the engine is putting out, and adjust the air/fuel mixture accordingly. If you move them down stream, I assume that it is going to read different mixture, and then throw a CEL.
In all honesty the cats, unless plugged, are not restrictive enough on our trucks to justify throwing the Magnaflows on.

 

Yeah the upstream O2 sensors will be fine, but there are 2 more that plug into the cats. I guess we will find a way to reuse the stock cats then. Thanks.