I just recently took my car in for smog, Maxima 2000 SE, and everything checked out perfectly but I had EXTREMELY high NOx levels, it was at 1400 at 25mph, the target was 400. I have a Greddy Exhaust, Y pipe, punched out Precat (only on the California model). I changed my spark plugs already, added a second cat behind the existing one and the NOx reading was only reduced to 1100. All my readings were well below the max except for my NOx. Do you guys have any idea what I can do to pass SMOG? I already spent way too much money on the CAT and the plugs *cough*... Any help is appreciated.

 

I think your punched out pre cat is the problem. Cats need a lot of heat to work properly. I think you really need the cat as close to the engine as possible to maintain enough heat in the cat for it to do its job.

 

Thanks, I'll try that next, that's going to be costly, the CAT near the engine is $600, sucks to live in California because only their models have one.

 

I have one on my 01 Maxima.... punched out also... I don't have any cats. Cats are really responsible for HCs- Hydrocarbons. Hydrocarbons are unburned fuel vapors that contribute to polution. Cat gets hot enough and burns the HCs. In IL they hook up their OBDII scanner on 96 and up cars.... and see if all the computer readiness tests have passed on the car. If they all passed they give U a pass card. I have no cats, and no check engine lights ( www.o2simulator.com ) my car passes the IL test with flying colors yet it stinks really bad at times that I feel sorry for people who have windows down in traffic.

 

How hard was it to install the o2 simulators? I take it you did it for the rear o2 sensors which look for a working cat, correct?

I'm thinking that since the rear o2 sensors give so much trouble one of the simulators can save alot of time and headaches having to go back to the dealer to reprogram the ECU etc.

 

Why would u need to reprogram the ECU? If u mean u just need to clear the ECU, all you have to do is unplug the car battery for a few hours (must be at least a few hours, I usually leave it unplugged overnight).

 

There is a TSB out that requires an actual reprogram of the ECU by Nissan to take care of an "incorrect" check engine light for the rear O2 sensors. It seems the factory settings for the rear O2 sensors was too tight causing many to throw a code when nothing is really wrong.

Since the rear o2 sensors have no effect on engine management, unlike the front o2 sensors which determine the correct air/fuel mixture, installing an O2 simulator for the rear sensors could save alot of time and headaches.

I'm wondering how hard it is to install one of these simulators.

 

Where Can u Purchase an o2 Simulator? And How do u put it on. THanks!

 

www.o2simulator.com For a CALI-spec get the dual wire one cause it don't cost any extra. Cali spec 5th gen has 2 post O2 sensors, where Federal has just one. I have the dual wire one on my 01 Max, no problems. 25 bux saves u alot of troubles. If there is enough interest I will write up which wires need to be tapped. I have been check engine light free for months