What does the term True Duels refer to. I bought a 04 FX4 5.4 110000mi. About a week later I had duels installed, pipe off each side side, after Cats, two mufflers and tail pipes. A few days later SES light came on PO171,PO175. Would exhaust change cause OBC to set those codes?

 

True duals means duals from the manifold/headers or cats back. The other type of "dual" system is SI/DO systems.
1. Did you have a crossover installed in your system?
2. Did the O2 sensor wires get touched accidently?

It seems odd to have one bank rich and one bank lean.

 

Here is a pic of true duals with x pipe.

 

No O2 sensor wires were touched. No X pipe, didn't know I needed one. Muffler shop didn't say anything about it. Does it need to be X shaped or can I just add a crossover pipe before the mufflers? Thanks, BJ

 

^ As close to where the two sides come together as possible. X shaped or H, it doesn't matter. Clean your MAF sensor too.

 

I'll add a crossover next week. MAF is OK. I've got an EDGE Evolution. MAF Voltage checks .7-5.0 Plus it's been changed. Thanks, BJ

 

Had cross over installed last week. Doesn't look like a very good job to me. Cross pipe is about 1/2 inside diamenter of the exhaust pipes. Exhaust pipes are only 2in. apart. Do I need to have it redone?

 

If you're not happy with it get it re done. Should look like the picture wrench78 posted above.

 

Did you have a X pipe or a H Pipe done? Can you take any pics of your set up. That might help people give you better advice.