Good vibrations

Frank explains the science behind the way-out sounds made by today’s cars that can be the cause of much head-scratching in the workshop

By Frank Massey | Published:  31 December, 2018

In a previous topic I expanded on the availability of focused test tools for independents. It’s not often that we see a technical breakthrough which has real application potential, but there was a breakthrough recently when Pico introduced a new NVH kit. It has come just in time, as noise, vibration and harshness is a challenge that’s not getting any easier, so what is it?

You must first start by accepting that the motor vehicle is a series of mechanical systems in permanent conflict. There are components travelling in different directions, subject to acceleration, deceleration, changing direction, and of considerable mass differential.

What I have just described there is the internal combustion engine. adding chassis and body systems to the mix. I think you will agree the problem we have is in identifying noise and vibration.

 The difference between noise and vibration is based on frequency and amplitude. Noise is a single event with a diminishing synodal pattern. It looks like a trumpet. Vibration however has a repetitive frequency and amplitude. Both of which will change with speed and a whole host of influences, resonance, beating, and mass differential are just some.  

So why has it become more difficult for us techs to bend our ear and diagnose an issue with confidence? The answer is due to the technical innovations of today’s vehicles. These include the dual mass flywheel, active engine mounts, cylinder cancellation, Audi anc system, infinite computer control of chassis dynamics, and the most obvious of all-  lack of accessibility.

Let’s begin with the basics. As we have seen, Vibration is classified by frequency and amplitude. A large mass will by nature have a lower frequency and a greater mass, while  a small mass will present the exact opposite. Two or more mass that converge with the same frequency combine their mass value increasing the amplitude. This is called resonance. Mass that have a similar but close frequency differential, within say 10hz, cause beating; “wo, wo, wo, wo.” An example of this would be a worn wheel bearing.
Vibration has three elements: Cause, transfer path, and respondent. In almost all cases we experience the respondent. Let’s think about the vibrating ash tray, wedged with paper to stop the noise! Vibration also falls into three other simple categories, vibration we feel, vibration we see, and vibration we hear. We humans can only hear noise between 25hz/22,000hz.

The next consideration is how many events per rotation frequency is experienced these are called, first, second, third, orders etc.
Now let’s do some simple maths. It’s getting interesting now isn’t it? We must convert everything into frequency, the unit is hertz, or cycles per second. For simplicity, a four-cylinder engine revolving at 3000rpm, in top gear 1:1, differential ratio 4:1.
3000/60=50hz divided by final drive ratio 4:1=12.5hz.

Therefore crankshaft vibration will be @50hz and tyres, rim, brake disc, and drive shafts will be at 12.5hz. So, you will now appreciate is a simple matter of separating the various operating frequencies.

Well not quite, but by now I’m hoping you view vibration in a more clinical way and not just based on experience or opinion. Vibration can have different direction or vectors, something tyre fitters more often or not get wrong.

Bring on the technology. The kit which can have an infinite flexibility of accessory options, uses a three-dimensional accelerometer, for vector differential, measuring mass, and a microphone recording sound, together with 1+3 channel interfaces, and bnc connection leads. The engine speed data is collected via the serial port with a drew tech mongoose serial interface. This can also be achieved optically if preferred. The accelerometer has a magnetic base and is directional sensitive, fore/aft, vertical, and lateral. Its initial position should be on the driver’s seat frame. After all that’s where the complaints start! The microphone could be positioned close to a known noise source or in the cabin.

Navigating through the software wizard is straightforward, you will need to select number of cylinders and configuration, in line, opposed, v config, and direction of mounting. You will then need to establish the various gear and final drive ratios, with tyre size data.

The software will then gather data over an infinite timeframe and scaling which is of course adjustable. The most challenging aspect in my opinion is control of the style of driving technique, speed, gearing, direction, braking and the influence of the road surface. The vehicle may have selectable drivetrain and suspension options, which will affect the potential effects of noise and vibration.

Did you remember not to omit the obvious or obscure effects? Has the vehicle been modified in any way whatsoever? Wheel size, spring rates, power output, etc, etc. Record your driving technique and environmental influences into the microphone. After all it is recording sound, all sound!

There are several options in the display menu, from bar chart, frequency, and 3D. you will quickly establish exactly which one of three vehicle systems the problem originates based on visual evidence. Engine, transmission or tyres.
You can then reposition the sensors to further locate the position of the source. Vibration will increase in amplitude, as will noise the closer you are to the source. This is due to the reduction in the length of the transfer path, and any devices that may absorb it.  
I can confidently monitor discrete combustion anomalies based on the transfer of mass energy from the pistons to crankshaft orders, simplifying connectivity issues with coil on plug multi-cylinder engines. I could show you images from a test I conducted recently, but a simple static image does not fully demonstrate the effects of vibration.



Related Articles

  • Part two The good and THE GREAT  

    In part one, we looked at the start of the ‘diagnostic process.’ The first steps were customer questioning, confirming the fault and knowing the system and its function. These help the technician to build the ‘big picture’ necessary to repair the vehicle correctly.
    In this article we will look at the next four steps.

    Step 4: Gather evidence
    It is easy to overlook this step as many technicians think of it as the overall ‘diagnosis.’ However, once the technician understands the system, gathering evidence will provide key information. This step is normally best carried out with the use of test equipment that does not mean the dismantling of systems and components.

    Many technicians have their own favourite tools and equipment but this list can include (but not limited to)
    the following:
    Scan tool – It is always best practice to record the fault codes present, erase the codes, and then recheck. This means codes which reappear are still current. Remember that a fault code will only indicate a fault with a circuit or its function. It is not always the component listed in the fault code that is at fault

    Oscilloscope – An oscilloscope can be used for a multitude of testing/initial measuring without being intrusive. Some oscilloscope equipment suppliers are looking at systems within high voltages hybrid/electric vehicle technology. The waveforms produced by the test equipment can be used when analysing the evidence and may indicate that a fault exists within a system. An understanding of the system being tested will be necessary to understand the information. This may even include performing sums so all those missed maths lessons at school may come back to haunt you. It may take time to become confident analysing the waveforms, so be patient

    Temperature measuring equipment – This can include the use of thermal imaging cameras. Most systems that produce energy/work will also produce some heat. The temperatures produced vary from system to system. Examples include everything from engine misfires to electrical components, as well as air conditioning system components and mechanical components such as brake and hub assemblies. The possibilities are endless and results can be thought provoking.

    Emission equipment – By measuring the end result, an exhaust gas analyser can show you if the engine is functioning correctly. The incorrect emissions emitted from the exhaust help indicate a system fault or a mechanical fault with the engine

    Technical service bulletins – Many vehicle manufacturers produce technical service bulletins (TSBs) that are generated by a central point (usually a technical department) from the information that is gathered from their network of dealers. Some of these may be available to the independent sector either through the VM or through a third party – It’s always worth checking if these exist. They may indicate a common fault that has been reported similar to that the technician is facing. Some test equipment suppliers may provide TSBs as part of a diagnostic tool package

    Software updates – Many vehicle systems are controlled by a ECU. Most vehicle manufacturers are constantly updating system software to overcome various faults/  customer concerns. Simply by updating the software can fix the vehicles problem without any other intervention of repairing a possible fault. This is where having a link to a vehicle manufacturer is vital in repairing the vehicle

    Hints & tips – Most technicians will have a link or access to a vehicle repair forum where they can ask various questions on vehicle faults and may get some indication of which system components are likely to cause a vehicle fault

    Functional checks – Vehicle systems are interlinked and typically share information using a vehicle network. The fault may cause another system to function incorrectly, so it is vitally important that the technician carries out a functional check to see if the reported fault has an effect on another system. By carrying out this check the technician again is building the big picture

    Actuator checks – Most systems today are capable of performing actuator tests. The technician can perform various checks to components to check its operation and if the system ECU can control the component, often reducing the time to the diagnosis, by performing this task the technician can identify whether it is the control signal, wiring or component or it is sensor wiring. This function can be used in conjunction with serial data to see how the system reacts as the component functions

    Serial (live) data – The technician can typically review a vehicle system serial data through a scan tool. Having live data readings to refer to can help you review the data captured. Using actuator checks and viewing the serial data can also help the technician to identify a system fault

    Remember to record all the evidence gathered so it can be analysed during the next step in the diagnosis. We can’t remember everything. If the technician needs to contact a technical helpline they will ask for the actual readings obtained recoding the data gathered will help.

    Step 5: Analyse the evidence
    Analysing evidence gathered during the previous steps can take time. The technician needs to build the big picture from all the evidence gathered during the first few steps. You need to analyse the information gathered, and decide on what information is right and wrong.

    This step may rely on experience as well as knowledge on the product. You should take your time – don’t be hurried. Time spent in the thinking stages of the diagnosis can save time later. Putting pressure on the technician can lead to errors being made. It may be necessary to ask the opinion of other technicians. If the evidence is documented it may be easier to analyse or share between others.

    Step 6: Plan the test routine
    After analysing the evidence gathered it’s now time to start to ‘plan’ the best way to approach to the task or tasks in hand.

    The technician should plan their test routine, decide on what test equipment should they use, what results are they expecting, if the result is good or bad  and which component should they test next.

    Document the plan – this enables you to review decisions made at this stage in the next step. The technician may not always get it right as there may be various routes to test systems/components. The test routine may have to be revisited depending on the results gathered during testing. Documenting the test routine will provide a map.  Also, don’t forget to list the stages, as this is something that could be incorporated into an invoicing structure later.

    The technician should indicate on the routine what readings they expect when they carry out the system testing. This can be generated by their own knowledge/skill or the expected readings may come from vehicle information which they have already sourced. If the information is not known at the time the test routine is planned, then the test routine may highlight what information is required and what test equipment is needed. You shouldn’t be afraid to revisit the plan at any time and ask further questions on which direction the tests should take. If the plan is well documented and the technician becomes stuck at any point, they can pause the process and revisit later. Also the information can then be shared with various helplines that support workshop networks.

    Step 7: System testing
    The technician then follows their pre-determined plan, if it is documented they can record the results of the test(s) as they follow the routine.

    Many technicians tend to go a little off-piste when they get frustrated. Having the routine documented can keep the technician on track and focused on the result. If the routine is followed and the fault cannot be found the technician may have to go back to the analysing the evidence or planning the test routine. The technician shouldn’t be scared of going back a few steps, as I said previously analysing the evidence takes practice and can be time consuming, not to be rushed.
        
    Summing up
    Remember to follow the process. It is easy to be led off track by various distractions but don’t try to short circuit the process. Some steps may take longer than first thought to accomplish than others. Some distractions may be outside of your control, and it may be necessary to educate others. Practice, practice, practice. Refine the process to fit in with your business and its practices, the business could align its estimating/cost modelling to the process, being able to charge effectively and keeping the customer informed at each stage of the process.

    Coming up...
    In the next article I will be looking at the next four steps which are; Step 8: Conclusion (the root cause), Step 9: Rectify the fault and Step 10: Recheck the system(s). The last article in this series will indicate the final three steps and how to fit them all together in order to become a great technician and perhaps succeed in Top Technician or Top Garage in 2018.



  • ADAS is the word 

    Advanced driver assistance systems (ADAS) have gone from a nice-to-have to a legal requirement in a relatively short space of time.

    It is a huge market and it is growing, so more and more cars coming through the door have these systems. This means that if garages don’t have the knowledge, training and equipment required to calibrate ADAS systems correctly, they could be ruling themselves out of business entirely.

    The future, today
    ADAS is the word, and it is the future, today. Robin Huish, Managing Director of Hickleys agrees: “ADAS was an increasing topic of conversation throughout 2018, continues to be in 2019 and this sure to continue  in the coming years. The level of ADAS systems being installed on new cars is increasing rapidly but that doesn’t mean this is something you can consider for the future; ADAS systems fitted to vehicles regularly coming into the independent garage need repair and calibration now.
    “If you want to offer a complete service to your customers you need to consider equipping your workshops and assembling the knowledge to deal with ADAS as soon as possible. One thing is for sure these systems are not going to go away and the demand for service and calibration will rapidly increase.”

    Camera and Radar
    Robin breaks down the opportunity: “ADAS systems are developed to improve safety and lead to better driving. Safety features are designed to avoid collisions and accidents by offering technologies that alert the driver to potential problems, or to avoid collisions by implementing safeguards and in some cases taking over control of the vehicle.
    “Broadly the market splits into two sectors, Camera and Radar. The equipment required to work with both systems varies. Camera was first to impact the independent market in a big way, with a front-facing camera fitted to a windscreen. When a windscreen is replaced the camera requires recalibration. Most windscreen replacement companies now are able to carry out this task with carefully chosen diagnostic scan tools and calibration hardware. This has now become a major part of their income stream. Recently the ability to offer mobile calibration equipment has again increased the opportunity for mobile diagnostic specialists to carry out these tasks. Of course, windscreen replacement is just one market sector that needs ADAS equipment. Crash repairers, diagnostic specialists, independent garages, fast fits and fleet workshops will all face the need to repair front and rear camera systems.

    “Radar is the fastest expanding area, firstly using front and rear detection but now covering the whole surrounding area of the car including blind spots, pedestrian detection, traffic signal information and emergency braking. The equipment required for radar calibration is similar to camera, again using carefully selected diagnostic scan tools and various radar attachments and accessories. This can be an expansion of the camera equipment using the same basic equipment and stand. Again for the mobile specialist, the equipment is easily transported.”

    Forward-thinking
    How does a garage incorporate ADAS into their business? “ADAS calibrations are usually around £150 to £250,” says Robin, “and diagnostic repairs where an ADAS system has failed adds many hundreds of pounds of revenue to a forward-thinking garage.”
    What about kit? “There is a range of equipment available from diagnostic suppliers such as Bosch, Texa and Hickleys’ exclusive brand RCCT. With prices from only £4,995 joining the ADAS boom is surprisingly easy with repayments from as little as £27 per week.”

    Robin says think before you leap though: “One word of warning is to carefully select your equipment and speak to a specialist that doesn’t represent just one brand. Get an
    on-site demonstration and review the options considering all aspects of the market, consider carefully your chosen diagnostic tool as well. ADAS information varies dramatically from tool to tool and some manufacturers are locking down their software so it can only be used with their hardware. This is fine if they cover everything but what happens if they fall behind, do you buy it all again from another supplier?”

    Choice
    As with many areas, independents need to be strong and fight their corner: “Despite recent comments – generally from the those affiliated to the vehicle manufacturers or bodies closely associated – discouraging independents from recalibrating ADAS systems,” says Neil Hilton, Head of Business Development for Hella Gutmann Solutions (HGS), “the fact remains that vehicles fitted with the technology are entering workshops daily. As a result, the sector needs to make a choice and either embrace it or ignore the opportunities it provides.”

    Legislation has its part to play: “Since 2016, to qualify for a 5 star Euro NCAP safety rating, the VMs have to fit their vehicles with, as a minimum requirement, autonomous emergency braking and lane departure warning. These are both complex systems that, following any intervention that affects their set-up, require specialist recalibration equipment to reset the cameras or radars on which the vehicle relies for its ADAS operation.”
    Neil continues: “This naturally includes accident damage and windscreen replacement, but it also encompasses general service and repair work, such as adjustment to the vehicle’s tracking or wheel alignment, as well as coil spring or steering component replacement. In short, anything that affects the vehicle’s geometry, because it is through this datum that ADAS functions are calibrated and then operate.”

    Commenting on the HGS offering, Neil says: “Clearly, VMs and their associates, do not want the independent sector to have any interaction with these systems, so unless independents are simply willing to cede the business back to the dealer, there has to be an aftermarket solution, which is what HGS has been championing for more than five years. HGS is the market leader for ADAS technology in the aftermarket and offers a comprehensive multi-brand solution, covering more than 92% of the UK’s ADAS equipped car parc. The company has become renowned for its knowledge and expertise on this complicated subject, with multiple high profile businesses, including Thatcham Research, the motor insurers’ automotive research centre and Autoglass in the UK and Europe, CESVI in France and AIG Insurance Group, using the Hella Gutmann Solutions CSC (Camera and Sensor Calibration) tool to establish the standards the sector should be meeting in regards to ADAS recalibration. Therefore, providing an independent goes through the correct procedure in terms of setting-up the equipment that comes with the CSC tool – an operation that once learned takes only 20 minutes or so – it can undertake ADAS recalibration with complete confidence and to the same standard as the dealer.”
        
    Another issue for VMs  is the quality of the parts used in any pre-recalibration repair as they  prefer the use of their genuine parts programmes, installed by an affiliated dealer.
    “From an aftermarket perspective however,” Neil concludes, “provided the independent uses replacement components of comparable quality to the OE part, which are installed following the correct procedure, the repair will conform with Block Exemption regulations and the recalibration will be valid, so allowing the independent to compete with the dealer in an open and fair market.”


  • No self control? 

    Having witnessed the growth of passive driver assist systems and the intent to move towards fully autonomous vehicle control, my topic this month is to raise both thought and debate towards the implications. My first intention is to separate assistance from autonomy.

    I fully support assistance as it provides a safer environment for the driver to concentrate on vehicle control. Many of these systems have been available for a very long time, including possibly the very first, power steering and power windows.

    ABS to power steering
    Anti-lock braking systems (ABS) are, I think, an excellent example where drivers may be misled as to the safety improvements. However, the laws of physics still apply, and the co-efficient of friction and kinetic energy will always dictate the retardation distance and vector. Obvious enhancements to ABS work as a fully integrated system, including dynamic chassis stability.
    Early variants simply monitored the wheel speed sensor frequency, reducing the engine throttle angle to reduce torque through the driving wheels when a significant differential existed. Recent additions now include variable geometry anti-roll bar and adjustable rate shock absorber damping with self- levelling.

    Evolving in parallel with these systems, and this is where there is an arguable transition from passive to active or automatous control, is the steering system. The introduction of power steering does have great advantages in reducing driver fatigue and improving mechanical response to steering wheel input. The next evolution was variable rate steering assist, whereby the assistance is proportional to steering angle and road speed. with the evolution of brushless motors and highly accurate position sensor technology, steering systems now offer corrective suggestion to the driver via a subtle torsion bar within the upper steering column. Should the driver resist this small force the system will disengage leaving the driver fully in control.
    I am choosing to ignore for the moment fully autonomous steering control as it embodies a whole array of additional control input requirements.  This allows me to focus on some of the more peripheral driver support systems which I do fully endorse. Matrix vehicle lighting control is possibly one of the best safety improvements. This enables full beam lighting always, yet avoiding oncoming vehicle light stray. Smart cruise control is also especially useful on motorways in uniform traffic conditions.

    Compliance
    The next group of driver assist starts to cross the boundaries of assistance, this is due to the introduction of long- range transmitters and receptors, lane divergence, and vehicle proximity awareness. This technology does of course lend itself to other previously mentioned systems.  

    There should be a very sobering pause at this point.  To maintain system integrity and accuracy from the above systems a little thought should be given to the almost non- existent function called calibration.it is critical. If you fully consider the implications of everyday servicing and repairs that affect these systems, compliance is the responsibility of the repairer. This means you.
    This is the point where I cannot avoid the transition towards full driverless autonomous control. Due to several critical considerations, technical compliance, political compliance, legal compliance, and public acceptance, it is to be rolled out in five steps over several years. Ford recently suggested it could be implemented by 2021, with level zero full human control, to level five where the human has no input responsibility.

    What of the globe’s biggest commerce giant’s? Intel has just purchased an Israeli autonomy tech company for $15 billion. Google has spent a modest $30m, and Facebook is in it too. All hellbent on convincing us of the benefits in total vehicle automation. Given their past and current dishonesty, self-interest, and responsibility avoidance you can bet it all going to be a financial beartrap.
     However, my personal feelings are more complex. Humans has evolved over many thousands of years by overcoming and controlling a multitude of challenges. It has enabled our brain and cognitive functions to develop to incredible levels. Imagine then, being trapped in an autonomous container with absolutely no functional requirement. What will you do by way of brain stimulation or choices. I accept traffic jams are worst than toothache, but driving is a socially shared experience. Think of the simple activities that release endorphins, such as cycling and walking. Why? because of the brain stimulation and cognitive responses, a form of achievement.

    If you must have total autonomy for your travel requirements, then public transport is available now. My acid test for the techno maniacs out there is, given that the technology is currently available and has been proven over several years, would you choose to fly in an aircraft with no pilot? Remember that even in autopilot there are teams of humans constantly monitoring the flight path and technical systems.

    Credibility
    I’m not ignorant of the accident statistics that give credibility to automation, if that was the true motivation, then smoking and alcohol would be banned tomorrow as they kill and maim an awful lot more.

    It has been suggested that our home environment would be improved as our car could drop us off and then park its self in a less congested place, so if you live in central London your car could end up in a South Downs village. On a more sinister note, if an autonomous vehicle faced with an inevitable collision from a oncoming car, would it mount the pavement and choose the mother with a pram as the better survivable outcome for its occupants?

    The very best qualities of life always come back to interaction, be it with other people, pets or machines, what next? When do machines decide we are the redundant component? Disagree, or debate, but don’t accuse me of not embracing technology, I have spent my life trying to master it.





  • Cut to the chase 

    Many modern systems, such as common rail diesel injection, can appear to be so complex that they seem to operate by magic. Over time, such systems are only going to become more and more complex, so understanding them means you can gain a head start on their repair.
        
    You can be presented with a seemingly endless amount of data relating to fuel pressure feedback, fuel pressure control, cam/crank synchronisation, measured mass airflow, injector flow correction feedback, and many other areas.
        
    However, if you prepare yourself with a fundamental understanding of the system and all data available pertaining to the fault, a systematic approach to the fault-finding procedure can be carried out.  
    Data overload

    Figure 1 shows  the live data returned from a common rail diesel injection vehicle with an EDC16 engine management system.
        
    There is an enormous amount of data available from these data parameters, which can allow you to ascertain the nature of the fault. The actual operation of the fuel system can be compared to the desired system operation and using the data, a decision can be made on the condition of the system and where a fault (if any) may be.
        
    An oscilloscope is another important tool when investigating a fault with such a complex system. Figure 2 shows an oscilloscope waveform from an Audi with the 2.0L common rail engine. The yellow trace is the fuel rail pressure sensor voltage (feedback) and the green trace is the current flow through the inlet metering valve (command). The waveform was captured during a wide open throttle (WOT) condition.
        
    This image alone tells us that the fuel inlet metering valve is a normally open valve. The engine control module (ECM) decreases the duty cycle when the required fuel pressure is increased. This allows less current to flow through the solenoid and the valve is allowed to open, which increases the fuel pressure measured at the fuel rail.

    Full analysis
    When the fuel pressure demand decreases, the duty cycle control from the ECM increases. This allows more current to flow through the solenoid which results in a reduction of the fuel pressure. Duty cycle is often referred to as pulse width modulation (PWM) control.

    The duty cycle control on the ground side of the fuel inlet metering valve can be analysed using an oscilloscope, as seen in Figure 3. The waveform below displays the fuel rail pressure feedback voltage (yellow trace) and the fuel inlet metering valve duty cycle control from the ECM (green trace).
        
    The oscilloscope is connected to the control wire for the fuel inlet metering valve. The technician must be mindful that this is the ground control circuit. System voltage on this wire indicates open circuit voltage. The diagram in Figure 4 shows the best method of connecting this set-up.
        
    By careful analysis using serial (scan-tool) and parallel (oscilloscope) diagnostics you will now be in a position to identify the area of concern accurately and in a timely manner. Knowledge, together with the right equipment and experience therefore benefits technicians by leading to a reduced diagnostic time and an easier fault finding method, rendering these complex systems much less so.

  • 888... Lucky for some 

    With this month’s focus in Aftermarket on cooling, I thought a look at how technology has affected one of the oldest systems of the internal combustion engine. For illustration, I have chosen the Volkswagen Auto Group’s en888 engine, built in Mexico, Hungary and China hence the 888 insignia; It is their lucky number.

    Its one of Audi’s high-performance variants. Its fitted in my Seat Cupra 2ltr, producing 400bhp with stock mechanicals. So, what are the benefits of advanced cooling systems? Heat derived from combustion, transferred by conduction and convection into cooling and the environment is in effect wasted energy. Controlling and where necessary containing it improves efficiency, not forgetting reductions in emission pollution.

    Efforts
    They have made stringent efforts in the mechanical design of the 888 to achieve savings in efficiency. Reducing engine weight, minimising internal friction, increasing power and torque, current with fuel economy initiatives.

    The cylinder block wall is reduced from 3.5mm to 3.00mm. Internal friction is reduced with smaller main bearing journals, revised timing chain design, incorporating a dual pressure lubricating system. The balance shaft has roller bearings, piston cooling jets further improve thermal stability. The jets have PCM mapped control, while extra oil cooling is provided adjacent the filter housing, close to the activation solenoid and twin oil pressure sensors.

    The engine can theoretically reach Lambda 1 from cold within 20-30 seconds.

    Further technical innovations include reduced oil level, reduced tension force in the auxiliary chain mechanism, down shifting achieved with variable valve lift and twin scroll direct mount turbo design.

    Advances
    You will now appreciate that it is no longer possible to separate mechanical design, power delivery, emissions, and all-round efficiency, treating cooling as an afterthought.

    Take the cylinder block design, which possibly has the biggest advances reserved within the cylinder head and coolant control module (water pump). The exhaust manifold is housed completely within the cylinder head casting. This ensures very effective conductance of heat. The emphasis is now on increase, maintain, reduce, thanks to an advanced dual valve PCM controlled coolant control module. The module is mounted at the rear of the engine block, belt-driven with a cooling fan to keep the belt cool.
    By manipulating the two rotary valves, flow and temperature can be effectively controlled within very carefully controlled limits. The rotary valves are manipulated by a PWM 1000hz motor with SENT position feedback (single edge nibble transmission), a method used by the latest air mass meters.

    Heat transfer into and from the turbo is much more efficient due partly to the direct mount and integrated cooling galleries surrounding the exhaust tracts.

    The piston to wall clearance has been increased, with a special coating on the piston thrust side complimenting a direct gudgeon pin to rod contact, the DLC coating removes the need for a bearing bush.

    The cylinder head porting incorporates ignition sequence separation, thus ensuring preceding exhaust pulses do not impede the energy from the current. This in combination with advanced turbine design further improves torque range and downshifting. Cooling control priority is applied to the occupants, then the transmission, further reducing frictional losses.

    Complexity
    Although not directly related to the cooling system, a dual injection system is fitted with its main function being emission reduction. Cold start is provided with three direct injection events, followed by port injection warm up. These systems do not run in tandem. Two thirds of the load range is controlled by port injection, with full load above 4,000 rpm delivered by induction stroke direct fuel delivery.

    From a practical point of view, previous low-tech tasks like replacing coolant components and bleeding now requires electronic support through the serial interface. Using the correct antifreeze is now essential if premature corrosion is to be avoided. As a warning, capillary coolant invasion within wiring looms is well known in some French and GM vehicles, as some of you will be aware.
    It is also worth mentioning that Volkswagen has modified the software controlling cooling in some of their diesel vehicles as part of the emission recall programme.

    Predictably due to their complexity, I can foresee cooling systems being neglected during routine servicing , so expect to see faults as these systems age in the pre-owned market.



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