It's a '97 so it's gotta pass "emissions". I put a quote around emissions because it's all done through OBDII. Anyways, I am running a straight pipe in place of the cat and I am not running oxygen sensors. The setup I am running I have a regular bung where I can screw in an o2 sensor and a special 90 degree elbow bung welded into the pipe as well (downstream of the straight defouler). Now, my original idea was to screw in two oxygen sensors in (one in the regular threads and one in the defouler) and plug them into the connectors and I thought it would trip the CEL. Now, my only problem is, I can't find the other place to plug in an oxygen sensor. According to the haynes manual the truck comes stock with two but I have traced the exhaust and been under the truck many times (even had it on a lift) and I still cannot find the other 4-pin connector to plug in an oxygen sensor. Has anyone played around with oxygen sensor simulators at all? Like I said, I can only find one place to plug in an o2 sensor so I'm not sure if it would work. Let me know what else I can do to permanently get rid of the CEL without paying the big bucks for a cat. thanks.

 

Wait, why are you not running oxygen sensors? You NEED the upper one so your computer gets the correct air/fuel ratio.

Move to Indiana, we have no emissions testing...And we have corn, plenty of corn.

 

First reply. I'm new here. And I just replaced my two O2 sensors and the first sensor is on the cat itself, so seeing how you removed the cat, im gonna guess you removed the sensor's housing too. The second sensor comes right after the cat. The pigtail of the the sensor on the cat goes along the bell housing and ends up mounted and plugged right on top. That's how my 98 5.9 was at least.

 

Yeah I know, I'm not too worried about air to fuel ratio right now. The truck runs fine as it is. When the CEL is on the truck runs in what is called limp mode so there is an extra 30HP that I will gain once I get rid of this CEL. Now, answer me this, if the upstream sensor is just for A/F ratio, can I just plug in one O2 sensor into the defouler I have and will it get rid of the CEL?

 

extra 30 HP? Not really.

You NEED an o2 sensor before the cat.

TO HELP YOUR PROBELM: use this in place of the after cat sensor:
http://www.thefastman.com/02Simms.asp
The defouler will not send back a signal. If you do not have o2 sensors hooked up, then you will throw a CEL. Simple as that.

I did not notice a HP gain after getting the sim for my 1996. Just smoother throttle.

 

Non-fouler works great for the after the cat O2, but won't do the trick on the pre-cat one. No way of getting rid of that CEL without installing a sensor that I'm aware of. Drill a hole, weld on a bung and stick a sensor in there and do the non-fouler for the rear one...

 

Hey, I appreciate you sending me the link for the O2 simulator. Now, the question I have that no one has been able to answer me is this... can I purchase just one O2 simulator and clear the check engine light? I am not concerned about the A/F ratio right now. I just need the CEL off. I am the 3rd owner on the truck so I don't know everything that has been done on the truck but in the exhaust I only have one 4-pin connector to plug in an O2 simulator. Will this product clear the CEL if I just use one of them?

 

No. It won't. The system expects to see input from TWO O2 sensors. Even if you have only one, it will still set a code, whining about the one that isn't there. Doesn't matter which one is missing.

There should be two connectors. Need to find out what happened to the other one, and see which one it is that you actually have. (pre- or post- cat)

For the cost of the O2 simulator, you could get a bung welded on, and that would probably pay for itself in fuel savings, as the O2 sensor is one of THE biggest factors, once the engine goes into closed loop. The post cat O2, you might be able to get away with a simulator, but, not 100% sure on that.

 

I agree. There has to be at least two plugs on that truck. You need the pre-cat sensor welded in and some type of defouler or simulator on the other one. The only other thing to check is if the truck already has the post cat hooked to a simulator stuck up out of the way or the pre cat sensor is up high on the exhaust that you can't see it. either way your ahead

 

rotflmao.......