MSLR Racing Parts

Exhaust Test

The Exhaust and Catalytic Market in the UK

Exhausts & Catalysts An exhaust is an exhaust, isn’t it? Just bent pieces of metal designed to get rid of fumes, right? Well, no, really.  

The exhaust system is now one of the most complex mechanical systems on a modern day car. Designed to meet exacting performance standards with regards to sound and emission control, the exhaust is often overlooked and misunderstood.  

Emission Control

If you remember the good old days when you needed 25 exhaust parts to cover the majority of cars on the then ‘traffic free’ roads then you may be struggling with the technology behind emission control. The complexity of product is now staggering. In today’s greener and more stringent world integrated emission control systems are critical to a vehicles performance.  From fuel consumption, to road tax, the government is keen to pursue legislation that drives a more efficient use of energy. This drives us all to be aware of the new types of technology available. CES UK have 25 years experience of exhaust and emission systems and according to Steve McCann, CES’s Trading Director the rate of change is phenomenal. In the next few paragraphs Steve gives us an overview of what the modern emission system consist of. 

A ‘Systems’ approach

Firstly, it is essential to understand that the collection of various exhaust parts should be considered as a system and that any replacement must be matched into that system. Where possible like for like product should be sourced and fitted to ensure optimum performance. It is not good practice to fit different tyre types to the same vehicle, so why do it with a critical performance item such as emissions? Secondly the system is part of the engine management system and as such is very susceptible to correct repair and fitting. In the ‘good old days’ an exhaust bandage or ‘gun gum’ would suffice. Not so today, any small air leak, change in gas flow, or back- pressure will seriously affect the system performance.  As an example any air leak before a catalytic converter can lead to poor running, increased fuel consumption or even cause the MIL (Malfunction Indicator Lamp) to illuminate. The result of this is usually an incorrect diagnosis of a Catalyst failure due to ‘OBD’ incompatibility, more of which later. 

Maniverter 

We are seeing more and more Maniverter (Manifold Converters) demand at CES UK, as the name suggests this type of Catalytic Converter is part of the manifold which ensures the Cat reaches a higher temperature faster. This gives a much quicker warm up time and faster light off to reduce emissions almost from start up. It is a compact design and generally mounted in the engine bay. The thermal stress on this component is significant therefore we source metallic substrates wherever possible which are more durable than ceramic ones.  Due to this complexity and the time taken to fit this item it is essential a high quality part is specified. The demise of remanufactured clutch demonstrates that the trade wants ‘fit and forget’ high quality products; this is also true for emission parts where the labour cost forms a high proportion of the total replacement costs.  

Close-coupled Catalyst

Similar to the Maniverter, the close coupled Cat is mounted as close to the engine as possible but is separate to the manifold. Again it is a complex unit and when replacing ensures that all the brackets and fixing points match the original. Due to the high temperatures involved it is critical that all shields and other protection devices are refitted as per the original to avoid any safety concerns. 

Under floor Catalyst 

The more common under floor catalysts is still the majority of repairs an Independent garage will see but it is becoming less effective due to its the longer light off time. The latest Emissions legislation is now so stringent this type will soon be obsolete and be replaced by the more efficient (and complex) types above. 

On-Board Diagnostics (OBD)

OBD is a standard that utilises the vehicles own control systems to ensure that the vehicle is not polluting between external checks (i.e. the MOT test) Pioneered in California this standard was mandatory in the UK from 2002 onwards. All catalyst products sold should meet this as a basic standard to demonstrate their fitness for purpose.  The term ‘OBD compliant’ is a misnomer as it is essential for correct operation. You would be surprised to hear the marketing pitch “buy our Alternators because they charge at 14.4 volts” the same is true for OBD compliance. In practice the emission gases are tested after any pollution control devices via an oxygen sensor similar to the lambda sensor on the vehicle and, if not within tolerance, the ‘MIL’ light illuminates. When replacing a Catalyst always ensure you fit a good quality Catalyst from a reputable supplier such as CES UK who ensure that all these compliance factors have been taken into consideration. You should also ensure that all gaskets and sealing devices are replaced therefore avoiding any MIL issues. 

Dirty Diesel?

The growth in Diesel vehicle sales and the specific concerns around the environmental issues caused by Particulate Matter (PM) have accelerated the development and introduction of diesel pollution control devices.  When we consider that nearly 50% of new cars sold are diesels and that Euro IV (2005-2007) and Euro V (due in 2009) emission regulations specifically target a major reduction in PM levels, these devices will become ever more common in garages. They will also be driven by the growth of ‘Low Emission Zones’ and Company Car Tax rules.  There are a number of different technologies and devices. Some are even ‘coupled together’ within a single system to target different emission types and offer a complete solution.  

Diesel Particulate Filter (DPF)

Also referred to as a soot trap this device is similar in shape to a Catalyst but that is where any similarity ends. The device forms a physical filter where the gases, containing the particulates, have to pass through the walls of the core rather than flowing through channels. This filters out the particulate matter resulting in low levels of smoke. As with any filter it requires cleaning which is achieved by some form of ‘regeneration’. This can be achieved in a number of ways but the more common method is to alter the vehicles fuelling characteristics by way of injection timing and duration to rapidly increase the temperature within the exhaust system to burn off the particulate deposits. Regeneration can be a very aggressive process. Therefore, it is imperative that replacement products and repair techniques are of a high quality to withstand the high thermal loads and stresses. 

Fuel borne catalysts 

Citroen and Peugeot have taken a typically French approach that relies on a more complex system for regeneration. Essentially a fuel additive (Cerine) is mixed with the diesel fuel to lower the combustion temperature of the particulate matter therefore enabling faster regeneration. The system consists of a separate Cerine tank within the main fuel tank, pump and associated control system. When the vehicle is refuelled this is detected by the control, system and the pump adds the correct amount of Cerine to the diesel fuel. During normal combustion the Cerine coats the particulate matter and reduces its combustion temperature. A pressure differential switch across the DPF detects when the filter is becoming clogged and initiates the regeneration process as detailed above.  This is an effective system but the DPF can eventually get clogged with Cerine deposits and will require replacement. CES UK stock both Original Equipment and Aftermarket replacement items. This appears to be highly complex system but with the correct diagnostic equipment, and the right knowledge, an independent garage can compete with the dealer to not only replace the DPF but also replenish the Cerine tank, replace any pipe work and reset the MIL.   

Selective Catalyst Reduction (SCR) 

This pollution control system is very prevalent on Commercial vehicles but is gaining popularity in the car world and has been developed to reduce oxides of nitrogen emissions.  In principle, a water based solution containing Urea is injected into the exhaust stream that contains nitrogen oxides. The Urea reacts to form a composition of Ammonia, water vapour and nitrogen oxides that then flows though a SCR catalyst which through a chemical process produces harmless nitrogen and water to the environment. The more common trade name for urea is ‘Ad-Blue’.  Suffice to say the different types of additives ,Cerine & Ad-Blue, should not be mixed or used on the wrong type of system! 

Fuel and lubricant quality 

At this point it is worth mentioning that the quality of fuel and lubricants directly affects the performance of an emission system. The use of Eco-Diesel, cooking oil or other low quality diesel will directly affect the performance of the emission system and possibly damage the diesel injection system due to the extremely high pressures involved, especially in Common Rail Diesels. Some manufacturers now even specify ‘low-ash’ or DPF specific engine oils to ensure that the Cat, DPF or SCR-Cat is not poisoned by harmful gases recirculated via the EGR system. If in doubt call us for advice.  

Silencers

Even the humble silencer is becoming more technically advanced, although it’s primary purpose is still to allow the hot exhaust gases to expand in a controlled manner so the sound can be reduced without compromising the system’s back pressure.  Due to weight considerations and under floor pack space limitations, we are seeing more and more complex shapes and different material types coming into stock. In practice here at CES UK we are supplying more OE type product from our large stocks. As drivers become more and more demanding even the exhaust system is becoming a fashion item with twin-tail pipes, chrome trims, carbon fibre boxes and a multitude of aesthetic enhancing products becoming ‘de-rigeur’ for even the most basic vehicles. 

Your right to repair

Your right to repair under Block Exemption means that you should follow the OE repair recommendations and fit OE product, or product matching OE quality from the aftermarket to keep the manufacturers warranty intact. If you follow the Block Exemption guidelines you are not limited to repairing cars that are more than three years old. As we have seen the emission system is a much more complex item that is called upon to carry out a multitude of tasks in very demanding conditions. All this said it still remains a very profitable portion of the modern independent garage’s repertoire.  With the correct products, support, training and information from CES UK this product group is far from exhausted.

CES UK provides exhausts and car part.  CES publishes technical bulletins and articles on new technology, the automotive market and offers technical advice on fitting and fault diagnosis. To learn more visit www.cesuk.com. 

About the Author

CES provides technical bulletins and articles regarding the automotive industry. CES specialise in emission control, exhausts and catalytic converters. Simon Moore is their Marketing Manager.

What kind of problems can an exhaust leak cause in a 2003 dodge ram 1500 ?

its a v6 4x2
i hear a humming noise when driving aroiund 35 mph and uyp but i cam not always hear it its really werid but i always hear it when i get up to highway speeds and only when my foots on the gas
if theres a way to test if it is an exhaust leak if some one oculd plz help

put it up on a grease rack with it running and feel along the pipe for air escaping from the pipe or fittings on it that will find the leak if there is one,if it does have one it can cause you to get a check engine light for a bad 0-2 sensor sometimes but not always,most of the tie you just get that annoying noise from it leaking,good luck.

Best Motoring - Honda S2000 Exhaust Test Modulo Mugen Spoon J's Amuse 5-Zigen Blitz Fujistsubo

Column: Showing your pride next to the exhaust pipe
Column: Showing your pride next to the exhaust pipe - Let me ask a rather Seinfeldian question: What is