I have a 99 5.2 with the dual to single back to dual exhaust. I am looking to rebuild it later, and I want true duals. I want it to agree with my computer, though. Certain 5.9 Heavy Duty engines had quad oxygen sensors to monitor dual pipes. Would my harness have connectors for this? Does anyone know what else this will involve? Thanks!

 

I put true duals on my 95 which only has one sensor before the cat. All is fine with my system. No check engine lights. On yours you would have to get like a $70 O2 sensor simulator to replace the rear sensor. Put true duals on my buddys 99 and did the same thing and his ran fine. I did weld a small crossover pipe up by the engine and put the front sensor in that so it would read the exhaust off of all 8 cylinders. Not sure if that is necessary for the sensor, but it helps builds mid to low range power.

 

get an o2 simulator or have an exhaust shop weld a bung into your new exhaust in approximate location of where the stock bung was. all 96 and above vehicles are OBD II computer controlled and the o2 sensors control air/fuel ratios. it would be nice if trucks were still OBD I or other prior computer controlled systems but we just cant get that lucky. hope this helps.

 

The Unofficial DodgeForum O2 simm outlet:
http://www.thefastman.com/02Simms.asp

 

+1 for the Fastman.

 

This would be great! I'm sure, however, that this is not legal.... if you get caught.... But I do have a question: doesn't the PCM use the o2 sensor input to monitor air/fuel ratios and adjust it accordingly? Or does it not matter? I'm worried that the fuel mileage and performance will drop...

 

The front sensor monitors the mixture, but the rear monitors whether there is a converter or not. To simply unplug this sensor would throw a check engine code. The O2 simulator replaces the rear sensor and tells the computer that there IS an O2 sensor present. If you did a true dual setup with 2 converters, you would be fine and presumably legal.

 

Sorry tells computer that there is a converter present.

 

and functioning properly.

If you're willing to install dual converters you could install the rear O2 behind the passenger side converter.

The best idea (I think anyway) would be to install a crossover pipe in front and behind the converters and install your O2 sensors in these cross over pipes.

Certainly a bit more expensive but I think it will give your engine controller the most accurate information and be the most legal should you ever get checked.

Contrary to popular belief the rear O2 sensor(s) also effect fuel trim a small bit

 

But can the engine still run efficiently with the simulators?