ScubaStevo80

Went to get inspected today and these were the results... car is a 95 civic cx with 102k miles.

Gas Standard Reading Result
NOx 1372 1483 Fail
HC 173 46 Pass
CO% .97 .09 Pass
CO2% 14.8
02% 0.2

CO2 and HC were well below limits. But NOx was high indicated combustion chamber temps are hotter than they should be. Would it be safe to say I can retard timing and go back and try to pass? I'm also going to change the EGR before I go back. I also only use 87 octane. Any other thoughts? Do the 02 and CO2 numbers relate in any way?

Magnaflow

Retarding the timing will make your Nox go up. It will cause you to run more lean. presence of 02 and lean conditions give you higher Nox.

You may have some carbon deposits in the engine that is causing the Nox problem.

Is this the stock converter? Stock motor? Any modifications?

JV

Here is a general list of things to look over courtesy of B20guy...

NOx failure:
1. EGR System
2. O2 Sensor
3. Timing/Spark Advance
4. Catalytic Converter
5. Incorrect/faulty thermostat
6. Coolant Temp Sensor may be open
7. MAP Sensor
8. MAF Sensor
9. Other sensors/switchs
10. Fuel Injection System
11. Faulty On-Board COmputer
12. Computer PROM
13. Internal Engine Repair

High HC Failure:
1. Spark Plugs and Wires
2. Timing Spark Advance
3. Vacuum Leaks
4. Other Ignition Problems
5. O2 Sensor
6 Evaporative fuel system
7. Fuel Injection System
8. Air/Fuel Mixture Adjustment
9. PCV System
10. Catalytic Converter(s)
11. Throttle Position Sensor
12. MAP Sensor
13. MAF Sensor
14. Other Sensors/Switchs
15. Computer PROM
16. Internal Engine Repair

High CO Failure:

In the case of carb engines, up to 85-86
1. Choke System
2. Carburetor Repair

In the case of fuel injected engines, from 1986 on,
1. Fuel Injection System
2. Induction system problems
3. O2 Sensor
4. TPS
5. MAP
6. MAF
7. Coolant Temp Sensor may be closed
8. Other sensors/switches
9. Valve train problems
10.Jumped engine timing belt
Plus...
Idle speed adjustment
Air Filter Condition
Thermostatic Air Cleaner
Air Injection/Reaction System
EVAP fuel system
Oil and Filter Change
Catalytic Converter
Computer PROM

Hybrid96EK

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by VolpeOwnsU &raquo;</TD></TR><TR><TD CLASS="quote">Went to get inspected today and these were the results... car is a 95 civic cx with 102k miles.

Gas Standard Reading Result
NOx 1372 1483 Fail
HC 173 46 Pass
CO% .97 .09 Pass
CO2% 14.8
02% 0.2

CO2 and HC were well below limits. But NOx was high indicated combustion chamber temps are hotter than they should be. Would it be safe to say I can retard timing and go back and try to pass? I'm also going to change the EGR before I go back. I also only use 87 octane. Any other thoughts? Do the 02 and CO2 numbers relate in any way?
</TD></TR></TABLE>

I have seen quite a few of those engines plug the EGR ports on the intake manifold/head. I would remove the EGR and check it for blockage.

93_hatch

yes check your egr for propor operation and that it works and check hoses for blockage and retarding ur timing will help lowwer nox magnaflow is wrong on that part advancing it makes the the combustion temps higher so more nox, retarding it lets the fuel cool the combustion camber which mean less nox but higher CO and maybe HC depending on the amount u retarded it but the Cat should clean that up

fasthatchb18c1

damn I guess im lucky I can take my car to some backyard mechanic to get my inspection, hope you pass next run