Recently my civic failed ca emissions testing due to excessive nox. I found that my cam timing was off 2 teeth and the car had an accord distributer(wtf?) after correctig these issues and setting ignition timing i figured that was case closed. However! I was severely disappointed as my car failed again, this time worse than before!
Readings are as follows
Emissions readings are as follows
15mph 25mph
Rpm: 1736 Rpm: 2774
Co2: 15%. CO2: 15.1%
O2: .2%. O2: 0.0%
Hc: 44ppm Hc: 17ppm
Co: .07%. Co: .02%
No: 2022ppm No: 1238ppm
Ignition timing is 17 btdc
Valve adjustment 5,000 miles ago
Oil change 200 miles
Mil is off
The only other noticeable issues are a slight vibration at idle and occasionally when i first start the car it feels like it will miss once or twice
Based on the specs its running very efficiently just really high nox
Thx in advance Any insight would be greatly appreciated!
Car is a 94 civic lx m/t completely stock

 

Is there a reason that you don't think the engine is running lean?

Post the actual spec sheet.

What car and engine?

 

Well i think if there was a lean condition i would see high levels of o2, co and higher hc.

 

Nox is high because it's running lean or running hot. Lean is fuel supply problems and hot is EGR problems. Start by cleaning the EGR and passages.

 

Both HC and CO are on the low side and even more so for the 25 mph test, which are indicative of running lean and a fuel supply problem - try replacing the fuel filter.

 

The fuel filter has 500 miles on it, the car had a fuel injection service 4,000 miles ago also my civic is not equipped with an egr valve

 

Measure the fuel pressure.

 

Ill get ahold of a gauge and see what it says that way o can check the pump and the regulator at the same time

 

Even if you get your nox down enough to pass you'll most likely fail the hc at 15/50 cause you're barely passing. Max hc: 66 and you measured 44ppm. (To me that's barely passing) anyway, hc is measure from unburned fuel, seeing how your already running way lean (or getting too much air) your hc will go up if you fix the nox problem by adding fuel to your system.


I wanna say its your o2 sensor. )