HOW - TO EMISSION CONTROL BASICS
Contents
1. PARTS 4 PLUS HOW TO EMISSION CONTROL BASICS Tool And Material Checklist O Bore Brush O Rag O Thermometer O Service Manual O Portable Vacuum Pump LI Hose O Screwdriver O Stiff Paper O Combination Wrench Set O Cleaning Solution O 3 8 Drive Socket Set O Tape O Tachometer O Safety Glasses or Goggles n jA eg leaner ed a ral overview of a vehicle repair procedure You should always refer to a gen rvice manual designed for you me cle pe H tailed instructions Parts Plus assumes no liability pu an rect procedure Before beginning any emissions work check to see what state law requires Some states require specific emission control systems for all registered cars Furthermore some states permit only licensed or qualified auto mechanics to test service and repair emission control systems NOTE Always wear safety glasses or goggles whenever doing work of any kind on a running engine PCV SYSTEM The PCV or positive crankcase ventilation system relies on intake manifold vacuum to move air through the crankcase when the engine is running A malfunctioning PCV system can cause Oil contamination sludge Increased oil consumption Contaminant vapors to escape from the dipstick tube oil filler cap valve cover gasket areas and other openings to the crankcase Oil to leak at any of the hose or tube connections around the engine or into the air filter housing The PCV system should be checked every 122. able vacuum pump to the motor 3 Apply 20 of vacuum The pressure reading should not drop below 10 of vacuum for a full 5 minutes 4 Bleed off the vacuum pressure 5 Apply 5 of vacuum while observing the damper door it should begin to lift from the bottom of the snorkel 6 Increase the vacuum to between 9 and 10 The damper door should now move to the full UP position If it does not replace it and recheck 7 Otherwise replace the sensor and recheck Vacuum Diaphragm Testing the vacuum motor diaphragm with a vacuum pump To replace the vacuum motor 1 Remove the air cleaner assembly 2 Disconnect the vacuum hose from the vacuum motor 3 Tip the motor slightly forward to disengage the lock and rotate it counterclockwise NOTE Some motors are fastened by rivets which must be drilled out 4 Unhook the motor s rod from the damper door 5 Check the damper door for freedom of movement 6 Insert the new motor s rod into the damper door 7 Position the motor assembly tongs into the proper openings Turn the motor clockwise until the lock engages firmly 8 Reinstall the air cleaner 9 Retest the operation of the damper door making sure it opens at the correct temperature To replace the sensor 1 Remove the air cleaner assembly 2 Turn the assembly upside down and remove the hoses from the sensor 3 Remove the sensor s retaining clips 4 Turn the air cleaner right side up and rem
3. against the rocker cover opening clean out the PCV valve hose and passage in the lower part of the carburetor 9 To clean the PCV hose wash it in a cleaning solution such as mineral spirits and use a bore brush to scrub out the interior walls Never soak a hose in a strong solvent such as carburetor cleaner this type of solution can swell the hose THERMOSTATIC AIR CLEANER SYSTEM In addition to controlling pollution the thermostatic air cleaner system aids in cold weather starts To test the system proceed as follows 1 Check the condition of the hoses and connections 2 Remove the air cleaner 3 Securely tape a thermometer next to the air cleaner sensor 4 Replace the air cleaner cover without the wing nut 5 With the engine off check the heat control damper door position through the snorkel opening Air Rubber Grommet Cleaner na Housing PCV Hose f toltntake l Manifold PCV Inlet Filter Inspection points in a typical PCV system If this passage is not open check for binds in the door linkage 6 Start and idle the engine With the temperature below 85 F the door should be up 7 When the door begins to move down remove the air cleaner cover and observe the thermometer it should be between 85 and 115 F If it is not check the vacuum motor Inspect the vacuum motor as follows 1 With the engine off disconnect the vacuum line from the vacuum motor 2 Connect a port
4. ect how the catalytic converter operates Make sure the spark plugs are in good condition and that the carburetor is properly adjusted by a qualified mechanic using an HC CO exhaust analyzer
5. efective Before buying a new one have a mechanic check it Carburetor CTO Switch Vacuum Amplifier 00 00 oo oo EGR system C SYSTEM D TEST 1 Start with a cold engine and be sure to work in a well ventilated area 2 Turn on the engine and have a helper hold a wadded rag over the tail pipe to restrict not stop the exhaust flow CAUTION Use a clean rag solvent or oil soaked rags can easily catch fire 3 Increase the engine speed 2000 to 2500 rpm while observing the EGR valve stem It should not move while the engine is cold If it does replace the CTO switch 4 Let the engine warm up and repeat steps 2 and 3 The EGR valve should move up 5 If it does not check the valve operation by performing steps 6 7 and 8 of the system A test 6 If the valve works properly remove the vacuum hose that runs from the backpressure sensor to the CTO switch at the sensor s end 7 Increase the engine speed 2000 to 2500 rpm If no vacuum is felt at the end of the hose the CTC switch must be replaced 8 If vacuum is felt the problem is in the backpressure sensor Consult the service manual before attempting to fix it Back Pressure Sensor EGR system D CATALYTIC CONVERTER Located between the engine and muffler the catalytic converter reduces hydrocarbon and carbon monoxide emissions It does not affect engine performance unless it becomes restricted However engine performance does aff
6. fails to operate when the engine is hot NOTE There are many different EGR systems If the one on your car is different from the ones shown consult the service manual Carburetor EGR Valve EGR system A SYSTEM A TEST 1 Inspect all vacuum hoses and connectors Replace any worn hoses and repair any loose or leaking connections 2 Mark the position of the EGR valve stem with the engine shut off 3 Watch the stem while a helper starts the car and lets it idle The stem should remain in the same position CAUTION Work in a well ventilated area and keep your hands clear of belts fan blades and other moving parts 4 Continue watching the stem as the engine speed is slowly increased If the stem begins to move up as speed increases the system is working Do not run the engine above 2500 rpm Observing EGR valve stem movement 5 If the valve does not open as the engine speed increases disconnect the hose from the EGR valve Let the engine idle 6 Disconnect the hose from the temperature sensor that runs to the carburetor this is an alternate vacuum source Full Engine Vacuum Hose An alternate vacuum source 7 Connect this hose to the EGR valve using a longer hose if needed If the car begins to run roughly or stalls the EGR valve is working correctly so instead check for a clogged passage or hose If the car runs the same the EGR valve must be cleaned or replaced 8 Remember to reconnect all
7. hosesproperly SYSTEM B TEST 1 Start with a cold engine and disconnect the vacuum hose from the EGR valve 2 Start the engine and slowly increase the speed to about 2000 to 2500 rpm 3 If vacuum is felt while the engine is still cold 50 to 60 F replace the CTO switch 4 If no vacuum is felt let the engine warm up then increase the speed 2000 to 2500 rpm 5 Vacuum should be felt now If not replace the CTO valve 6 If the CTO switch is working let the engine idle and perform steps 6 7 and 8 of the system A test to check the EGR valve Switch EGR system B SYSTEM C TEST 1 Start the engine and let it warm up to its normal operating temperature 2 Watch the EGR valve stem while a helper quickly increases the engine speed to 2500 rpm Do not over speed the engine 3 If the EGR valve stem does not move go on to the next step Otherwise repeat step 2 with the engine cold If the valve does not move the system is operating properly If it does move replace the CTO switch The EGR system should not operate when the engine is cold 4 Remove the vacuum hose from the EGR valve 5 Perform steps 6 7 and 8 of the system A test to check the valve 6 Ifthe EGR valve is operating correctly remove the upper vacuum hose from the CTO switch 7 Increase engine speed 2000 to 2500 rpm 8 If vacuum is felt at the hose replace the CTO switch 9 If no vacuum is felt the vacuum amplifier is probably d
8. months or 12 000 miles whichever comes first Make a thorough check of the system as follows 1 Inspect the hoses They should not be hard brittle or cracked and the connections should not be loose or sloppy The PCV system must be airtight to operate efficiently 2 Replace any deteriorated hoses and fix any loose connections 3 Start the engine and remove the PCV valve If the valve is not plugged a hissing noise will be heard as air passes through it and a strong vacuum should be felt when a finger is placed over the inlet valve 4 Reinstall the PCV valve then remove the breather element On some cars the breather element is located inside the air cleaner on others it can be found on the rocker cover 5 Loosely hold a piece of stiff paper over the opening in the rocker cover After allowing about 1 minute for the crankcase pressure to decrease the paper should be sucked against the opening in the rocker cover with noticeable force 6 Turn off the engine and remove the PCV valve from the rocker cover Shake it and listen for a clicking noise to indicate that the valve is free 7 If the system has checked out fine so far no further service is required if not the PCV valve should be replaced and the system rechecked NOTE In the event of problems install a new PCV valve Do not clean and reuse the old valve 8 With the new PCV valve installed and the engine running repeat step 5 If the paper is still not sucked
9. ove the sensor and gasket 5 Install the new sensor gasket and retaining clips 6 Reinstall the air cleaner and attach all hoses FUEL EVAPORATION CONTROL SYSTEM This system prevents fuel vapors from escaping through the fuel tank or carburetor thus improving gas mileage The charcoal canister absorbs vapors from the fuel tank and carburetor when the engine is not running when the engine is started these vapors are drawn into the engine and burned To check the system proceed as follows 1 Locate the charcoal canister It is usually black plastic or round metal and is found on the inner fender pan close to the radiator Charcoal canister locations 2 Check the canister hoses for cracks hardness brittleness rub marks and loose connections 3 Remove the canister from the holder Turn it over and remove and discard the fiberglass filter 4 Install the new filter be careful not to tear it 5 Replace the canister in the holder Keep in mind that metal canisters have no filter 6 Check the rubber gasket on the gas tank filler cap If it is cracked or pieces are missing replace the cap Checking the rubber gasket on the gas tank filler cap EGR SYSTEM The EGR or exhaust gas re circulation system is responsible for reducing nitrogen oxide emissions It can cause roughness if it operates during idle wide open throttle cold starts or warm up The EGR system can also cause spark knock if it
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