you'll quickly find that one of the key factors in getting a clean burn, and low emissions is a strong ignition spark that's correctly timed, which requires a tune up in many cases and a strong battery voltage,and a decent ignition, (check your coil,cap,rotor,wires and timing advance) and a fuel / air ratio thats stays close to 14:1-15:1 during the lower idle-5000rpm power band,(IF its a carburetor equipped engine ,verify your float levels and fuel pressure) some modifications to the stock engine that usually help is a non-restrictive air filter and a multi strike ignition, and maintaining the correct engine temperature, and making sure theres no vacuum leaks and fresh spark plugs and it sure helps if the engines rings and valve seals are not worn.
naturally the fuel you use and the engines general condition effect results, one old trick to clean out combustion chamber fouling and reduce emissions, is to get the engine up to operating temps then to slowly dribble about a quart of a 50%/50% mix of water and ethanol alcohol thru the carb, while blipping the throttle as the steam produced in the combustion chamber tends to loosen and clean out carbon and combustion chamber deposits, do this a couple hours before the emission test, if you have a fuel injected engine run a can of fuel injection cleaner thru the engine and install a new fuel filter if the injectors get a bit sluggish from fuel contaminates the spray droplets are larger and burn slower causing higher emissions, the newer injector designs tend to FOG fuel in a cloud vs a STREAM like first design injectors
partly clogged injectors, or injectors running at over 80% duty cycle tend to reduce power and increase emissions
a really strong ignition spark helps reduce emissions so install new spark plugs gaped at about .045-.050 and if its a HEI, new cap and rotor and spark plug wires might be a good is a as will verifying your ignition advance curve and spark at the plugs, you'll generally want this curve below for an ignition advance curve, as a start point, obviously you need to verify timing so check your timing per the fsm (factory shop manual)
a leaking intake gasket or leaky head gasket will fairly frequently suck oil mist from the lifter gallery., or allow coolant to seep into the combustion chamber only after the engine heats up and parts expand, and oil thins, and/ or coolant pressure increases and if the intake sucking oil mist will usually burn to ash during combustion, leaving that residue , now obviously if the amount of oil mist or coolant entering the cylinder is minimal the smoke or lack of smoke due to complete or almost complete combustion will be minimal
READING THROUGH these LINKS AND SUB LINKS may help
http://garage.grumpysperformance.co...lay-switch-locations-and-info.728/#post-43477
http://garage.grumpysperformance.com/index.php?threads/what-kills-o2-sensors.3049/#post-51701
http://garage.grumpysperformance.com/index.php?threads/failed-emissions.11501/#post-52995
viewtopic.php?f=70&t=202
viewtopic.php?f=50&t=268&p=18428#p18428
viewtopic.php?f=55&t=109
http://garage.grumpysperformance.co...cleaning-dirty-fuel-injectors.1906/#post-5032
Ive had good results adding a can of either one of these, on particularly dirty or suspect injectors Ive added a can of both but one on one fill-up and the other product on the next full tank of fuel.
related info
http://www.smogtips.com/failed-emissions-test.cfm
http://www.smogtips.com/trouble-codes.cfm
http://garage.grumpysperformance.com/index.php?threads/failed-emissions.11501/#post-52995
http://www.aa1car.com/library/tr1196.htm
http://www.aa1car.com/library/2000/ic60032.htm
http://www.automotiveu.com/zack5gas.htm
http://www.auto-repair-help.com/auto_di ... ailure.php
A. WHAT CAUSES HIGH HYDROCARBON (HC)?
Below are common failures which are likely to produce high Hydrocarbon HC. Hydrocarbons are basically raw fuel, otherwise known as un-burnt Gasoline. High Hydrocarbon (HC) emissions are almost always a sign of poor fuel ignition. However, it's not always that the engine's ignition system is responsible for high Hydrocarbon emissions. Read on.
1. Improper Ignition Timing - Engine ignition timing is measured in degrees before or after Top Dead Center (TDC). Example of an ignition timing failure would be in the case where an engine's ignition timing is required to be set at 10 degrees Before Top Dead Center (BTDC) and instead is set to 15 degrees BTDC. This fault will not only cause a smog check "functional failure", but will increase Hyrdocarbon (HC) emissions as well. California allows 3 degrees +/- off of the manufacturer's required setting. Note: Late model vehicle's may not have a distributor, and therefore no timing adjustment will be needed. On these engines timing is electronically controlled by the ECU (Engine Control Unit).
2. Defective Ignition Components Your vehicle's ignition system consists of the ignition coil/s, distributor*, distributor cap*, distributor rotor*, ignition wires, and spark plugs. If any of these components are defective the engine will produce high hydrocarbons. A common reason ignition components perform poorly is due to carbon build-up. High ignition voltage traveling through the air pockets within these components form carbon. Carbon acts as an insulator between paths of electricity, decreasing the energy required at the spark plug to ignite the air/fuel in the combustion chambers properly. *Distributor-less engines do not have these components.
3. Lean Fuel Mixture - Any condition which will cause unmetered air to enter the intake manifold, and ultimately the combustion chambers, will cause high hydrocarbons (HC). This condition is called a lean miss-fire. Such faults as vacuum leaks and gasket leaks will cause lean fuel/air mixtures. Broken, disconnected or misrouted vacuum hoses will do the same. It is also important to note that many engine components rely on engine vacuum for proper operation. If any of these components are defective, externally or internally, they may cause large vacuum leaks as well. A good example of such a component is your vehicle's power brake boost
4. Defective Catalytic Converter - A defective catalytic converter (CAT) may be responsible for high HC, CO, and NOx emissions. The Catalytic Converter, commonly referred to as the CAT is a component designed to continue the combustion process within itself and emit a more thoroughly burned and less harmful emissions containing exhaust. The most accurate way to find out if your vehicle's CAT is working efficiently is by using an exhaust gas analyzer. Unfortunately this tool is fairly expensive. Testing the CAT should be conducted at a smog check repair station.
Some obvious symptoms of a bad CAT could be any of the following:
a. Major loss of power over 15-25 mph. This may be an indication that the catalytic converter is plugged up and restricting exhaust flow.
b. Strong sulfer or rotten egg smell emitting from the exhaust on an otherwise good running vehicle. This may be an indication that the Catalytic Converter isn't burning fuel completely, instead storing it, then releasing it as hydrogen sulfide.
c. Loud rattle being heard from inside the CAT. This may indicate a broken Catalytic Converter substrate. You may want to insure this sound is not due to loose exhaust components, i.e. broken muffler flanges, loose exhaust pipes, loose or cracked exhaust manifold.
5. Defective Air Injection Components - Faulty smog pump and related emissions system components will cause high HC. The air injection system is designed to introduce additional oxygen, after the metering system, to the engine exhaust as it exits the exhaust manifold, or directly before it enters the Catalytic Converter; thus burning whatever remaining fuel (HC) in the exhaust completely.
6. Low Cylinder Compression - This fault is one of the less common high HC causing problems we encounter. Reasons an engine may have low or no compression in one or more of its cylinders may include things such as burned intake or exhaust valve/s, defective valve guides and/or seals, defective piston rings, and burned head gasket/s. A wet/dry cylinder compression test will diagnose this fault. More then often if such a problem exists it will be very apparent. You should notice rough idle.
B. WHAT CAUSES HIGH CARBON MONOXIDE (CO)?
Below are common faults which are likely to produce high Carbon Monoxides (CO). Carbon Monoxide is a by-product of incomplete combustion. Carbon Monoxide exceeding maximum limits, can be due to a number of emission failures ranging from inadequate air intake to defective engine computer sensors.
1. Dirty Air Filter - The number one overlooked emissions component, yes, "emissions" component is the engine air filter. A dirty air filter will absolutely restrict air flow, thus disturbing the proper 14.7:1 air/fuel ratio required for optimum fuel combustion.
We recommend replacing the air filter at the manufacturer's required intervals; usually every 15,000 miles, or at least before your vehicle's smog check.
2. Faulty Oxygen Sensor (O2 Sensor) The Oxygen Sensor is responsibly for delivering information to the ECU (engine control unit) or ECM (engine control module) relating to the oxygen content in the exhaust stream after it has left the combustion chambers.
The engine control computer will determine how much fuel to inject into the combustion chambers based on this data. The more oxygen in the stream, the more fuel the computer will deliver, and visa-versa. A defective O2 sensor will cause increased carbon monoxide emissions. More about oxygen sensors.
3. Defective Manifold Absolute Pressure (MAP) Sensor - The MAP sensor determines the level of vacuum created during an engine's intake stroke, and sends this information to the ECU. During low vacuum the MAP sensor assumes the engine's throttle is in some degree open, meaning you've stepped on the pedal. It relays this information to the ECU. The ECU, in turn, sends commands to the fuel injectors, or carburetor, to increase fuel delivery.
A defective MAP sensor will not report the correct information to the ECU, thus disturbing air/fuel ratio. Usually when the ECU senses a defective MAP sensor it will learn to ignore its data, and rely on preset values, and other sensors such as the Throttle Position Sensor (TPS), and Engine Coolant Temperature (ECT) Sensor; Fuel delivery will not be as accurate and high CO may result.
4. Defective Throttle Position Sensor (TPS) - Obviously a very important emissions sensor; the TPS relays information regarding the position of the air intake system's throttle plate. The throttle plate, located after the engine air filter and before the intake manifold controls the amount of air entering the combustion chambers. It is usually manipulated by the gas pedal via a cable. On late model vehicles the throttle plate may be controlled electronically. A defective throttle position sensor will confuse the ECU into thinking the vehicle's operator is demanding more or less fuel, when neither is really neccessary. Most often a faulty TPS will cause high CO, as an engine's ECU always prefers to send more fuel rather then less, in an effort to avoid a lean fuel mixture and subsequently higher engine temperatures.
5. Defective Engine Coolant Temperature (ECT) Sensor - Low engine temperature requires more fuel. When the ECU is unable to determine what the engine's accurate temperature is, it will not adjust fuel delivery properly; resulting in high CO. As explained above, the Engine Control Computer prefers to send more fuel rather then less to avoid a lean fuel mixture.
C. WHAT CAUSES HIGH NITROUS OXIDE (NOx)?
Nitrous Oxide or NOx is created when an engine's combustion chamber temperature reaches over 2500F. Vehicle manufacturers have designed several systems, which when working properly, lower nitrous oxide emissions. Below are common failures which may cause your car, truck, van, suv, or motorhome to produce high high nitrous oxide.
1. Lean Fuel Mixture - Lean fuel mixtures cause high NOx. A lean fuel mixture exists when less fuel then required is delivered to the combustion chambers or when more air then necessary is added to the fuel. In either case the lack of gasoline needed to cool the combustion chambers down is not present. Combustion temperatures increase causing high nitrous oxide emissions. A lean fuel condition may be due to a vacuum leak/s and/or defective fuel control components, such as the Air Flow Meter, Engine Coolant Temperature Sensor, and O2 sensors.
Read more about the Oxygen Sensor
2. Defective EGR System - The Exhaust Gas Recirculation system is designed to reduce NOx. The EGR system consists of an EGR valve, EGR pressure sensor, vacuum hoses, and one or more vacuum switching valves or solenoids. Later model vehicles may be equipped with electronically controlled EGR valves, which do not require vacuum lines or switching solenoids. Electronic EGR systems will have these components built in.
The EGR system's job is to re-route a small amount of exhaust gas back into the intake manifold to help reduce combustion chamber temperatures. As mentioned above NOx is created when combustion chamber temperatures reach above 2500F.
By recirculating exhaust gas back into the intake, a small amount of the air/fuel mixture is replaced with inert gas, reducing combustion temperatures.
Read more about the EGR System
3. Defective Catalytic Converter (CAT) Some vehicle manufactures have designed their cars to operate without EGR valves. Non-EGR equipped vehicles rely heavily on the Catalytic Converter to assist in the reduction of NOx. These vehicles have tendencies to develop CAT problems sooner then those which are equipped. If you own a non-EGR equipped vehicle, and have failed the emissions test for high NOx, pay close attention to the Catalytic Converter.
Read more about the Catalytic Converter
4. High Engine Mileage - Over an engine's lifetime, carbon build-up develops in the engine's combustion chambers. The more miles on your engine, the more carbon build-up on the pistons, cylinder heads and valves. Carbon build-up decreases the available space for the air/fuel mixture to combust, and causes higher cylinder compression. High compression results in high temperatures and high NOx. Keep in mind this problem is usually seen in vehicles with over 150,000 miles which have been poorly maintained. The solution to this problem is called De-Carbonizing. It usually costs around two labor hours at a smog check repair station. It will remove a good amount of carbon out of an engine. This will increase combustion space, lower compression and lower NOx.
5. Engine Overheating - Inadequate engine cooling can will high NOx. If your vehicle's cooling system is not working efficiently, (i.e. bad radiator, thermostat, hoses) high NOx will be created. Remember high NOx nitrous oxide is created when an engine's combustion chamber temperatures reach over 2500F. You will want to make sure your vehicle's cooling system is working properly, and your vehicle's temperature gauge is always indicating normal.
naturally the fuel you use and the engines general condition effect results, one old trick to clean out combustion chamber fouling and reduce emissions, is to get the engine up to operating temps then to slowly dribble about a quart of a 50%/50% mix of water and ethanol alcohol thru the carb, while blipping the throttle as the steam produced in the combustion chamber tends to loosen and clean out carbon and combustion chamber deposits, do this a couple hours before the emission test, if you have a fuel injected engine run a can of fuel injection cleaner thru the engine and install a new fuel filter if the injectors get a bit sluggish from fuel contaminates the spray droplets are larger and burn slower causing higher emissions, the newer injector designs tend to FOG fuel in a cloud vs a STREAM like first design injectors
partly clogged injectors, or injectors running at over 80% duty cycle tend to reduce power and increase emissions
a really strong ignition spark helps reduce emissions so install new spark plugs gaped at about .045-.050 and if its a HEI, new cap and rotor and spark plug wires might be a good is a as will verifying your ignition advance curve and spark at the plugs, you'll generally want this curve below for an ignition advance curve, as a start point, obviously you need to verify timing so check your timing per the fsm (factory shop manual)
a leaking intake gasket or leaky head gasket will fairly frequently suck oil mist from the lifter gallery., or allow coolant to seep into the combustion chamber only after the engine heats up and parts expand, and oil thins, and/ or coolant pressure increases and if the intake sucking oil mist will usually burn to ash during combustion, leaving that residue , now obviously if the amount of oil mist or coolant entering the cylinder is minimal the smoke or lack of smoke due to complete or almost complete combustion will be minimal
READING THROUGH these LINKS AND SUB LINKS may help
http://garage.grumpysperformance.co...lay-switch-locations-and-info.728/#post-43477
http://garage.grumpysperformance.com/index.php?threads/what-kills-o2-sensors.3049/#post-51701
http://garage.grumpysperformance.com/index.php?threads/failed-emissions.11501/#post-52995
viewtopic.php?f=70&t=202
viewtopic.php?f=50&t=268&p=18428#p18428
viewtopic.php?f=55&t=109
http://garage.grumpysperformance.co...cleaning-dirty-fuel-injectors.1906/#post-5032
Ive had good results adding a can of either one of these, on particularly dirty or suspect injectors Ive added a can of both but one on one fill-up and the other product on the next full tank of fuel.
related info
http://www.smogtips.com/failed-emissions-test.cfm
http://www.smogtips.com/trouble-codes.cfm
http://garage.grumpysperformance.com/index.php?threads/failed-emissions.11501/#post-52995
http://www.aa1car.com/library/tr1196.htm
http://www.aa1car.com/library/2000/ic60032.htm
http://www.automotiveu.com/zack5gas.htm
http://www.auto-repair-help.com/auto_di ... ailure.php
A. WHAT CAUSES HIGH HYDROCARBON (HC)?
Below are common failures which are likely to produce high Hydrocarbon HC. Hydrocarbons are basically raw fuel, otherwise known as un-burnt Gasoline. High Hydrocarbon (HC) emissions are almost always a sign of poor fuel ignition. However, it's not always that the engine's ignition system is responsible for high Hydrocarbon emissions. Read on.
1. Improper Ignition Timing - Engine ignition timing is measured in degrees before or after Top Dead Center (TDC). Example of an ignition timing failure would be in the case where an engine's ignition timing is required to be set at 10 degrees Before Top Dead Center (BTDC) and instead is set to 15 degrees BTDC. This fault will not only cause a smog check "functional failure", but will increase Hyrdocarbon (HC) emissions as well. California allows 3 degrees +/- off of the manufacturer's required setting. Note: Late model vehicle's may not have a distributor, and therefore no timing adjustment will be needed. On these engines timing is electronically controlled by the ECU (Engine Control Unit).
2. Defective Ignition Components Your vehicle's ignition system consists of the ignition coil/s, distributor*, distributor cap*, distributor rotor*, ignition wires, and spark plugs. If any of these components are defective the engine will produce high hydrocarbons. A common reason ignition components perform poorly is due to carbon build-up. High ignition voltage traveling through the air pockets within these components form carbon. Carbon acts as an insulator between paths of electricity, decreasing the energy required at the spark plug to ignite the air/fuel in the combustion chambers properly. *Distributor-less engines do not have these components.
3. Lean Fuel Mixture - Any condition which will cause unmetered air to enter the intake manifold, and ultimately the combustion chambers, will cause high hydrocarbons (HC). This condition is called a lean miss-fire. Such faults as vacuum leaks and gasket leaks will cause lean fuel/air mixtures. Broken, disconnected or misrouted vacuum hoses will do the same. It is also important to note that many engine components rely on engine vacuum for proper operation. If any of these components are defective, externally or internally, they may cause large vacuum leaks as well. A good example of such a component is your vehicle's power brake boost
4. Defective Catalytic Converter - A defective catalytic converter (CAT) may be responsible for high HC, CO, and NOx emissions. The Catalytic Converter, commonly referred to as the CAT is a component designed to continue the combustion process within itself and emit a more thoroughly burned and less harmful emissions containing exhaust. The most accurate way to find out if your vehicle's CAT is working efficiently is by using an exhaust gas analyzer. Unfortunately this tool is fairly expensive. Testing the CAT should be conducted at a smog check repair station.
Some obvious symptoms of a bad CAT could be any of the following:
a. Major loss of power over 15-25 mph. This may be an indication that the catalytic converter is plugged up and restricting exhaust flow.
b. Strong sulfer or rotten egg smell emitting from the exhaust on an otherwise good running vehicle. This may be an indication that the Catalytic Converter isn't burning fuel completely, instead storing it, then releasing it as hydrogen sulfide.
c. Loud rattle being heard from inside the CAT. This may indicate a broken Catalytic Converter substrate. You may want to insure this sound is not due to loose exhaust components, i.e. broken muffler flanges, loose exhaust pipes, loose or cracked exhaust manifold.
5. Defective Air Injection Components - Faulty smog pump and related emissions system components will cause high HC. The air injection system is designed to introduce additional oxygen, after the metering system, to the engine exhaust as it exits the exhaust manifold, or directly before it enters the Catalytic Converter; thus burning whatever remaining fuel (HC) in the exhaust completely.
6. Low Cylinder Compression - This fault is one of the less common high HC causing problems we encounter. Reasons an engine may have low or no compression in one or more of its cylinders may include things such as burned intake or exhaust valve/s, defective valve guides and/or seals, defective piston rings, and burned head gasket/s. A wet/dry cylinder compression test will diagnose this fault. More then often if such a problem exists it will be very apparent. You should notice rough idle.
B. WHAT CAUSES HIGH CARBON MONOXIDE (CO)?
Below are common faults which are likely to produce high Carbon Monoxides (CO). Carbon Monoxide is a by-product of incomplete combustion. Carbon Monoxide exceeding maximum limits, can be due to a number of emission failures ranging from inadequate air intake to defective engine computer sensors.
1. Dirty Air Filter - The number one overlooked emissions component, yes, "emissions" component is the engine air filter. A dirty air filter will absolutely restrict air flow, thus disturbing the proper 14.7:1 air/fuel ratio required for optimum fuel combustion.
We recommend replacing the air filter at the manufacturer's required intervals; usually every 15,000 miles, or at least before your vehicle's smog check.
2. Faulty Oxygen Sensor (O2 Sensor) The Oxygen Sensor is responsibly for delivering information to the ECU (engine control unit) or ECM (engine control module) relating to the oxygen content in the exhaust stream after it has left the combustion chambers.
The engine control computer will determine how much fuel to inject into the combustion chambers based on this data. The more oxygen in the stream, the more fuel the computer will deliver, and visa-versa. A defective O2 sensor will cause increased carbon monoxide emissions. More about oxygen sensors.
3. Defective Manifold Absolute Pressure (MAP) Sensor - The MAP sensor determines the level of vacuum created during an engine's intake stroke, and sends this information to the ECU. During low vacuum the MAP sensor assumes the engine's throttle is in some degree open, meaning you've stepped on the pedal. It relays this information to the ECU. The ECU, in turn, sends commands to the fuel injectors, or carburetor, to increase fuel delivery.
A defective MAP sensor will not report the correct information to the ECU, thus disturbing air/fuel ratio. Usually when the ECU senses a defective MAP sensor it will learn to ignore its data, and rely on preset values, and other sensors such as the Throttle Position Sensor (TPS), and Engine Coolant Temperature (ECT) Sensor; Fuel delivery will not be as accurate and high CO may result.
4. Defective Throttle Position Sensor (TPS) - Obviously a very important emissions sensor; the TPS relays information regarding the position of the air intake system's throttle plate. The throttle plate, located after the engine air filter and before the intake manifold controls the amount of air entering the combustion chambers. It is usually manipulated by the gas pedal via a cable. On late model vehicles the throttle plate may be controlled electronically. A defective throttle position sensor will confuse the ECU into thinking the vehicle's operator is demanding more or less fuel, when neither is really neccessary. Most often a faulty TPS will cause high CO, as an engine's ECU always prefers to send more fuel rather then less, in an effort to avoid a lean fuel mixture and subsequently higher engine temperatures.
5. Defective Engine Coolant Temperature (ECT) Sensor - Low engine temperature requires more fuel. When the ECU is unable to determine what the engine's accurate temperature is, it will not adjust fuel delivery properly; resulting in high CO. As explained above, the Engine Control Computer prefers to send more fuel rather then less to avoid a lean fuel mixture.
C. WHAT CAUSES HIGH NITROUS OXIDE (NOx)?
Nitrous Oxide or NOx is created when an engine's combustion chamber temperature reaches over 2500F. Vehicle manufacturers have designed several systems, which when working properly, lower nitrous oxide emissions. Below are common failures which may cause your car, truck, van, suv, or motorhome to produce high high nitrous oxide.
1. Lean Fuel Mixture - Lean fuel mixtures cause high NOx. A lean fuel mixture exists when less fuel then required is delivered to the combustion chambers or when more air then necessary is added to the fuel. In either case the lack of gasoline needed to cool the combustion chambers down is not present. Combustion temperatures increase causing high nitrous oxide emissions. A lean fuel condition may be due to a vacuum leak/s and/or defective fuel control components, such as the Air Flow Meter, Engine Coolant Temperature Sensor, and O2 sensors.
Read more about the Oxygen Sensor
2. Defective EGR System - The Exhaust Gas Recirculation system is designed to reduce NOx. The EGR system consists of an EGR valve, EGR pressure sensor, vacuum hoses, and one or more vacuum switching valves or solenoids. Later model vehicles may be equipped with electronically controlled EGR valves, which do not require vacuum lines or switching solenoids. Electronic EGR systems will have these components built in.
The EGR system's job is to re-route a small amount of exhaust gas back into the intake manifold to help reduce combustion chamber temperatures. As mentioned above NOx is created when combustion chamber temperatures reach above 2500F.
By recirculating exhaust gas back into the intake, a small amount of the air/fuel mixture is replaced with inert gas, reducing combustion temperatures.
Read more about the EGR System
3. Defective Catalytic Converter (CAT) Some vehicle manufactures have designed their cars to operate without EGR valves. Non-EGR equipped vehicles rely heavily on the Catalytic Converter to assist in the reduction of NOx. These vehicles have tendencies to develop CAT problems sooner then those which are equipped. If you own a non-EGR equipped vehicle, and have failed the emissions test for high NOx, pay close attention to the Catalytic Converter.
Read more about the Catalytic Converter
4. High Engine Mileage - Over an engine's lifetime, carbon build-up develops in the engine's combustion chambers. The more miles on your engine, the more carbon build-up on the pistons, cylinder heads and valves. Carbon build-up decreases the available space for the air/fuel mixture to combust, and causes higher cylinder compression. High compression results in high temperatures and high NOx. Keep in mind this problem is usually seen in vehicles with over 150,000 miles which have been poorly maintained. The solution to this problem is called De-Carbonizing. It usually costs around two labor hours at a smog check repair station. It will remove a good amount of carbon out of an engine. This will increase combustion space, lower compression and lower NOx.
5. Engine Overheating - Inadequate engine cooling can will high NOx. If your vehicle's cooling system is not working efficiently, (i.e. bad radiator, thermostat, hoses) high NOx will be created. Remember high NOx nitrous oxide is created when an engine's combustion chamber temperatures reach over 2500F. You will want to make sure your vehicle's cooling system is working properly, and your vehicle's temperature gauge is always indicating normal.