The visual check is one of the most important points of the exhaust emissions test. This should be performed thoroughly, as many incorrect evaluations can thus be excluded.
There are two checklists (petrol and diesel) with lists of the most important check items.
Questions to the customer:
- When was the last Main Service/Inspection performed (Service Booklet)?
- What is the fuel consumption (problems with the mixture preparation/control)?
- Is the vehicle used for short journeys (premature ageing of the catalytic converter)?
Special instructions are listed as follows:
- Visual check of all exhaust emission-relevant components for presence, completeness, absence of leaks and damage, provided that this is possible without removal.
- Check catalytic converter for mechanical damage by tapping.
- Visual check catalytic converter housing for over-heating (red/violet discoloration).
Fuel System, Filler Cap and Safety Device
The new edition of the EGE test guidelines includes, in point 3.4.2.2, a requirement to check the fuel filler cap and its retaining strap or other safety device installed and described by the vehicle manufacturer. This check is to be carried out as part of the visual check.
The visual check of the fuel filler cap and its safety device on Opel vehicles generally involves checking the existence and function of the throat and the existence and function of the overflow limiter in the fuel tank filler neck. The overflow limiter comprises a spring-loaded flap at the top of the fuel tank filler neck. It is always closed, except when filling the tank with fuel. To carry out the test, use a suitable tool (e.g. pencil) to check that the flap opens and automatically closes.
The Agila has a fuel filler cap with retaining strap. The latter must be checked in these vehicles.
A new fuel filler cap has been fitted in the Astra-H. Unlike other vehicles in which the tank ventilation is fitted in the fuel filler pipe, in the Astra-H with diesel engine the tank ventilation is located in the fuel filler cap. This means that these vehicles may only be used with this fuel filler cap and therefore have an additional retaining strap on the fuel filler cap to prevent the wrong cap being used.
Pre-condition for effective minimising of pollutant emissions, apart from correct engine adjustment, is the general engine condition, such as:
- Air cleaner element
- Spark plugs / glowplugs
- Absence of leaks in the intake and exhaust muffler systems
Leaks in the intake and exhaust system as well as defective oxygen sensors are the most common cause of failure of the EGE (exhaust gas emissions) test.
Visual Check of Components:
Check pollutant-related components including exhaust system for presence, completeness, leaks and damage as far as is possible without dismantling. This includes, in particular, the catalytic converter, oxygen sensor and, if necessary, fuel vapour retention system, exhaust gas recirculation systems, secondary air systems and sensors and actuator lines.
Check the fuel filler cap and its retaining strap or a different retaining device installed and described by the vehicle manufacturer. The visual check on the fuel filler cap and its retaining device is undertaken on Opel vehicles in that the presence and ability to operate of the fuel filler cap mounting is checked as is the presence and ability to operate of the overflow protection in the fuel filler neck. The overflow protection consists of a spring-loaded flap at the end of the fuel filler neck. It is always closed except when refuelling. The check takes place by testing that the flap opens and closes automatically using a suitable tool (e.g. a pencil). The Agila and the Astra-H have a fuel filler cap with a retaining strap. This must be checked on these vehicles (see "Visual Inspection and Function Check, Fuel Filler Cap and Retaining Device").
Result of visual check, components, - not satisfactory / - satisfactory.
Connect the read out device to the diagnostic system interface in the vehicle; the location of the diagnostic system interface is given in the nominal data:
Visual check of engine diagnostic system control lamp, for existence and function:
Start ignition.
Engine diagnostic system control lamp must light up.
Result of visual check, engine diagnostic system control lamp, ON.
Start engine and run at idle speed.
Engine diagnostic system control lamp must go off. Result of visual check of control lamp, OFF.
Set up communication between the read-out device and the control unit. The read-out device must automatically recognise all the communications protocols authorised by Directive 98/69/EC. The read-out device automatically selects MODE 01 "actual data" in the OBD system for the control unit. If communication cannot be set up at the first attempt, the process may be repeated. To do this, switch off the ignition and disconnect the read-out device from the diagnostic system interface, then repeat from "Connect the read-out device to the diagnostic system interface in the vehicle ...". The overall result of the OBD EGE test is "failed". In the notes section of the test certificate put: "Communication setup failed". In such cases, check to see if Opel has released a specific procedure in the event of communications problems. Then try again, restarting the test device. If this does not work either, the overall result is "failed".
Sensors
All current petrol-engined vehicles have spring sensors (S). Vehicles with Y/Z 19 DT OHC engines and Y/Z 19 DTH DOHC diesel engines and no DPF have an oxygen sensor.
Diesel Particulate Filter (DPF)
Thanks to a new type of regenerative process, fuel consumption CO 2 -emissions and performance remain at almost the same level as without a filter. Purification is designed in such a way that all the exhaust emissions are reduced effectively in interaction with a pre-catalytic converter close to the engine and an under-floor catalytic converter, In addition to soot particles, this consists of hydrocarbons (HC), and carbon monoxide (CO).
Opel commenced mass-production of the innovative diesel particulate filter technology at the beginning of 2004 in the Vectra series and in the Signum with the newly developed 1.9 CDTI ECOTEC engine, which is also described in the "New Technical Features MY 2004.5".
The new diesel particulate filter consists of a solid ceramic honeycomb made of silicon carbide through which microscopically small channels pass. The flow of exhaust gas passes through the walls of the channels and the soot particles collect on their surfaces. The particles deposited must be burnt off regularly to prevent the filter becoming blocked. The so-called regeneration phase relies on a precious metal coating on the filter substrate and targeted multiple injection which raises the exhaust gas temperature of the diesel engine to the ignition temperature of 600 degrees Celsius which is required for the combustion process in the filter. An injection system which can make the requisite flexibility available in every engine load range is a pre-condition for this. Thus the system should work at its optimum not only when under full load but also when "cold", for example in short urban journeys when working as a taxi.
To be able to fulfil these requirements, Opel favours direct engineering using the most modern generation of the common rail system for its diesel models. This technology enables the quantity injected and its pressure to be controlled in accordance with need and as can the injection pattern for the fuel in the cylinder.
A further advantage of the intelligent Opel / GM-solution: the regeneration takes place in non-continuous intervals, adjusted to the respective style of driving. That means that the combustion of the soot particles deposited and therefore the subsequent injection of fuel only takes place when back-pressure occurs in the filter because of deposits. This process is controlled by pressure and temperature sensors in the area surrounding the DPF unit - the driver does not notice this process at all.
In addition to the "start cat" close to the engine, an oxidizing catalytic converter is located upstream of the particulate filter which oxidizes the HC- and CO-emissions with the aid of the atmospheric oxygen in the diesel exhaust gas. The nitrogen oxide emissions are reduced below the Euro 4-limit value by internal measures in the engine. This configuration guarantees that the engines will meet future exhaust gas regulation.