Vacuum Test: Restricted Exhaust

The catalytic converter is made of an aluminum oxide honeycomb coated with platinum and palladium. These components react to remove CO and HC's from the exhaust stream. A two-way catalytic converter works by oxidizing CO (carbon monoxide) and HC (hydrocarbons or unburned fuel) to carbon dioxide and water. A three-way catalytic converter also removes oxides of nitrogen NOx from the exhaust. Nox is formed at high cylinder temperatures. The EGR system is responsible for inhibiting NOx.

When a vehicle is running rich the catalytic converter is working harder and running hotter than it was intended. This heat can damage the substrate and cause it to melt and degrade. The result can be excessive back pressure caused by a clogged or plugged catalytic converter. Sometimes the substrate will become loose. If the converter rattles when tapped with a plastic hammer it must be replaced.

An easy way to test a catalytic converter for a rich fuel condition is to use a pyrometer to compare the inlet and outlet temperatures. A pyrometer is a handheld infrared thermometer used to measure temperature from a distance. At normal operating temperature the outlet temperature should always be more than the inlet. If this temperature is in excess of 200°F the engine is likely running rich. Late model catalytic converters have less temperature difference between the two.

Symptoms of a clogged catalytic converter include a loss of power and the vehicle will be extremely sluggish because of the restricted exhaust flow. The technician in this question uses a vacuum gauge to confirm an exhaust restriction. If the needle on the gauge drops steadily at 2500 RPM check the exhaust for a restriction. This will likely be a clogged catalytic converter.

Use can also use a back pressure tester to confirm a restricted exhaust system. Remove an upstream oxygen sensor and screw in the back pressure tester fitting. Usually the specifications will require back pressure to be below 1.0 psi. at idle and no more than 4 or 5 psi.at snap throttle. There's a big difference between a late model vehicle and an older model. Always check with vehicle manufactures specifications.

A/C Receiver Drier Function

Receiver driers are used on TXV thermal expansion valve systems. They are similar in operation to the accumulator used on the fixed orifice tube system because they both remove moisture from the system. There are some key differences though, this part is located on the high side of the system between the condenser and the evaporator. You may recall that the accumulator is located on the low side between the evaporator and the compressor on fixed orifice tube air conditioning systems.

The receiver drier is a liquid storage tank for the refrigerant coming from the condenser. This insures that the necessary liquid refrigerant is consistently supplied to the TXV under all operating conditions. At the most demanding times of the day the opening expansion valve relies on this storage tank to provide the evaporator core its supply of liquid refrigerant.

The receiver drier also contains a desiccant capable of absorbing moisture from the refrigerant and a filter that collects any unwanted debris in the system. Please note that any time this desiccant is exposed to the atmosphere it will absorb moisture and humidity from the air and must be replaced. Also any time the compressor is replaced the receiver drier must be replaced as well. This is because any debris in the system from the compressor is trapped in the filter located inside the drier.

Refrigerant from the condenser enters the receiver drier through the inlet port. The vapor rises to the top while the heavier liquid refrigerant drops to the bottom. It passes through the filter and desiccant and is then stored in the bottom of the tank. As the expansion valve opens and closes the liquid refrigerant is drawn into the outlet port tube, through the high pressure line, and onto the TXV.

Refrigerant Identifiers

Refrigerants should never be intentionally mixed. The most common cross contamination are the two most common refrigerants, R12 and R134a. This is the mixture of the older R12 refrigerant that contains chlorine with R134a. Chlorine was found to cause damage to the earths ozone layer and has been replaced with the newer and environmentally safer R134a.

They are in research for an improvement as R134a itself is found to contribute to global warming. These refrigerants must be contained as it is unlawful and unethical to release them into the atmosphere. Today's manufacturers use R134a as their preferred refrigerant.

These two should not be mixed in an AC system because they are two different compounds with different temperature to pressure characteristics. The mixture is called azeotrope. Though the low temperature to pressure characteristics of azeotrope may be close to 134a, the high temperature high pressure characteristics vary considerably. The symptoms of this blend result in high system and head pressures. High head pressure will cause the compressor and other system components to fail prematurely.

Use a refrigerant identifier or refrigerant gas analyzer any time a refrigerant mixture is suspected. These devices typically detect R12, R134a, R22, air, and hydrocarbons. Hydrocarbon gases like butane and isobutane often set an audible alarm and may be explosive and hazardous to the technician or occupants of the vehicle. It will display the amounts of each type of refrigerant as a percentage of the total blend.

An added advantage of using one of these tools is that it will also inform the technician of the amount of air in the system. The average shop recycling machine is incapable separating R12 and R134a. There is a special procedure and equipment for handling and separating these mixed refrigerants.

A/C Refrigerant Leak Detection

Proper oil levels in automotive air conditioning systems are vital to system performance. If the level is too low the compressor will starve for lubrication and fail. If the level is too high heat exchange is affected resulting in poor A/C performance. If a component has been replaced, or if a seal or leak left the system low on oil it must be replaced.

Refrigeration oil is distributed throughout the system in the refrigerant. If a leak is present on a hose or at a connection an oil spot will appear. This wet spot is likely collecting dirt and can be helpful in diagnosing the cause of a low refrigerant condition. Some oils contain dye that can be seen with a black light and special yellow tinted glasses. This dye can also be injected into a system with hard to find leaks to aid in visual diagnosis.

Always use manufacturers specifications and recommendations for adding oil to a system. Today's R134a systems use PAG (polyalkylene glycol) oil of different viscosities. PAG has replaced the mineral oil used in older R12 systems. This oil is highly hygroscopic meaning that it absorbs humidity from the air. Keep the lid on the container when your done and always add only the recommended amount for reasons mentioned earlier.

If the recovery machine is incapable of injecting oil into R134a A/C system after evacuation, use a manual refrigerant forced oil infector in the yellow line between the refrigerant container and the manifold gauge set.

Heater Control Valve

The heater core is the main component of the passenger heater system and uses engine coolant to provide heat to the passenger compartment. A heater control valve controls the amount of coolant flowing through the heater core. It is not used in all heater systems as some manufacturers allow coolant to flow through the heater core any time the engine is running.

The heater control valve allows the flow of coolant through the heater core to be controlled and switched on and off without effecting the operation of the rest of the engines coolant system. It may be located on the inlet or the outlet port of the heater core and activated by a cable , electronic control, or a vacuum signal. Its also important to note that the valve may be normally open allowing coolant to flow until activated or normally closed allowing coolant to flow only when activated.

The cable operated heater control uses a cable to drive a flap located inside the valve. As the occupant moves the lever in the dash a cable moves a flap in the valve that either allows of blocks the flow of coolant into the heater core.

The vacuum valve does the same thing with a pintle and diaphragm except this type of valve is normally open. This is in case of malfunction, heat may still be provided to the occupants by the heating system. Vacuum is supplied by the engine through a switch in the dash.

Electronic control can be PWM (pulse width modulated) or by a simple on/off solenoid. Pulse width modulation offers more control and is used is a variety of systems found through out the vehicle. The number of on an off pulses sent from the computer in a certain amount of time determines the position of the solenoid. The control valve may also be either opened or closed by a signal from the BCM.

It's also important to note that a poorly operating thermostat will effect the operation of the vehicles heating system. If the heater control valve is stuck closed depriving the heater core of heated coolant the inlet hose to the heater core will be hot and the outlet hose much cooler. This may also be caused by a clogged heater core. A leaking heater core will typically leak on to the floor board and result in a sweet humid odor coming from the vents while in operation.

Manifold Gauge Readings

Troubleshooting the A/C Compressor

An A/C manifold gauge set is used to get a look at what's going on inside the A/C system. The low side or suction pressure, the high side or discharge pressure along with a few vent outlet temperatures will tell a technician a lot about an air conditioners performance. It's important to listen to the customer, understand the type of air conditioner, and have a good understanding of how an automotive air conditioner works.

An automotive air conditioner has a high and low side divided by a metering device and the A/C compressor. With the clutch engaged, a normally functioning compressor pulls vapor in from the suction side and discharges the vapor at a higher temperature and pressure through the discharge side. These pressures and temperatures are highly predictable and affected by the ambient or outside temperature. The pressures in the system increase as the ambient temperature increases and decrease as the ambient temperature decreases. Always compare readings with manufacturers specifications and charts when diagnosing A/C performance.

When the low side is high and the high side is low, the A/C compressor (reed valves) are most likely the problem whether it is a CCOT (cycling clutch orifice tube) or a TXV (expansion valve) system. Note that when a system is static and not in operation the system pressures are equalized and are very close to each other. It's normal for some vehicles to make a slight hissing sound while equalizing just after a vehicle is turned off.

As the A/C compressor wears and gets weak the high and low side readings of the system also start getting closer to each other. As the compressor gets weaker the customer may notice it runs cooler at higher speeds. This is because as the compressors piston seal wears it looses its compression. When the engine is revved the compressor is able to compensate for the loss in compression and increase system pressure.

CAMPRO ENGINE

THE CAMPRO ENGINE

Developed in partnership with Lotus Engineering, this engine grants PROTON complete vehicle design independence. Its breakthrough engine technology produces low fuel consumption, yet gives rapid, high power response, and can even be produced to run on alternative fuels.

It represents true world-class powertrain engineering, and a revolutionary step forward in engine manufacture, with low toxic emissions, low noise levels and above all, highly economical maintenance with long service intervals.

MAJOR DESIGN OBJECTIVE

•- Space-saving transverse east-west direction engine installation•- Designed for long life of at least 10 years or 250,000 km•- Best performance in class•- Flexibility to use future technology (CPS & NGV)•- 80% recyclable to meet 2005 requirements•- Comply to future exhaust emission legislation requirement

CAMPRO UNIQUE DESIGN FEATURES
Modular Engine Design - Common Cylinder, Piston, Camshaft.Design Protected for future Combustion Technology (AVT),  Performance Technology (CDA & CPS), Low Emission (DI-NGV, Diesel.)


CAMPRO CPS ENGINE TECHNOLOGY (CPS & VIM)

The CamPro engine utilises two ingenious technologies to give high power and rapid response, whilst maintaining low fuel consumption. Cam Profile Switching (CPS) and Variable Intake Manifold (VIM) technology.

Together, these technologies provide the best of both worlds, essentially combining the best characteristics of two different engines in one compact package. The usual reduction in peak torque caused by High Lift cams is corrected by the Long Runner. The short runner works with the high lift cams to re-tune the engine and generate more power at high speed.

CPS & VIM : HOW IT WORKS

Engines create power from combusting a mixture of fuel and air. Valve lift creates a gap to draw air into the combustion chamber, and this gap influences the ratio of air in the mixture. Ordinary engines have fixed rate of valve lift, but Cam Profile Switching gives variable valve lift, for optimised airflow into the engine. A High Lift cam profile improves maximum power, whilst the Low profile offers fuel efficiency and low emissions.

Air is supplied to the valves by the engine’s intake manifold. Variable Intake Manifold technology intelligently changes the rate of “breathing” according to the engine speed. At low speed, air is drawn through the Long Runner manifold. The resulting slower air flow allows for more efficient, thorough mixing of air with fuel. At high speeds, the Short Runner takes over to supply more air for combustion, faster.

IAFM (Intake Air Flow Module)

The CamPro engine is now enhanced with a new air intake management system - the Integrated Air Fuel Module (IAFM) technology. It helps the engine "breathe" better to offer you the best of both worlds - greater fuel efficiency at low speeds and better performance at high speeds. Be it a short one to the shops or a cross-state roadtrip, be assured that every drive will be one you'll enjoy. 

CAMPRO TECHNICAL SPECIFICATIONS

	1.3L CAMPRO IAFM	1.6L CAMPRO	1.6L CAMPRO CPS
VALVE MECHANISM	16-Valve DOHC	16-Valve DOHC	16-Valve CPS DOHC
TOTAL DISPLACEMENT	1322cc	1597cc	1597cc
BORE	76mm	76mm	76mm
STROKE	73.4mm	88mm	88mm
MAX OUTPUT (kW/rpm)	70/6000	82/6000	93/6500
MAX TORQUE (nm/rpm)	120/4000	148/4000	150/4500
FUEL TYPE	Petrol	Petrol	Petrol