The Tools for the job

Frank Massey looks at creating your own tools and methods

By Frank Massey | Published:  01 May, 2017

I gave this topic some considerable thought before choosing to discuss not just a selection of tools we use, but also some tools we have designed and modified.

I guess we all agree on one thing, the continuous demand on tools and technology in virtually every aspect of vehicle diagnosis, repair, and service.

IÂ’m not sure of any other industry that places such demands on technical investment, yet it remains mainly unappreciated by the public. ThatÂ’s our fault! I did spend several years in the aircraft industry on the Panavia Tornado, several years on I often refer to the very similar demands and skill sets required.

 

Gauge interest
The first range of tools are ones we are particularly proud of as we designed them. A range of gauges to measure air and fluid pressures. I donÂ’t want to blow my own trumpet, but focus on the demand and challenges in using them. Some time ago I found it difficult to obtain quality gauges for simple measurements, often those on offer were designed by people who did not fully appreciate the full requirements, and practical application.

Development came progressively over several years, the first to come was a vacuum and turbo boost pressure gauge. We have specialised in performance tuning for many years, assessing engine mechanical efficiency and turbo boost control.

Requirements were a range of -1+2 bar, a tell tail indicator and a non-damped, large clock face. Monitoring turbo pressure can be achieved serially, however unless you can confirm real time pressures against the map sensor, and equally important, the PCM control response in real time, discrete deviations may not be observed. ItÂ’s important that the gauge not be fluid damped as this reduces the response time of the indicator.

I have witnessed sticking variable vanes many times, where serial data has been unable to monitor deviation. We often use two gauges at the same time, one on control value with the other on the charge pressure circuit. At the same time, we monitor PCM control request with a scope, as a suggestion look at current through the actuator it simplifies understanding of mechanical control response.

Prime example
The next gauge development came from our common rail programme, the requirement to monitor low pressure fuel priming. To be accurate we did use a gauge for many years with petrol systems, diesels however increased the demand with the introduction of suction priming. I’m going to make a comment here and expand on it later in the year: there is no such thing as vacuum, it’s simply a pressure lower than atmosphere. Think of it as pressure differential the greater it is the greater the flow potential.  The reverse logic of this is air flow differential creating lift (aeroplanes).

The gauge requirements were for a range of -1+10 bar, Perspex sight block minimum flow diameter 8mm, a ball valve tap to interrupt flow and to be undamped.

The obvious need is to monitor pressure in real time but also flow and the speed in flow response. Additional to this we wanted to restrict flow totally in suction systems, proving system seals integrity and pressure differential to a maximum of absolute zero. the tap also allows for increasing supply pressure whilst monitoring current flow through the low-pressure fuel pump electrical circuit. We call it proof test the increase in pressure and current is normally linear.

So, letÂ’s reverse that logic, you should be able to prove the performance of any fluid system by monitoring rise time and current flow with a scope. this will confirm filtration restriction, cavitation and other issues. The gauge can be used for oil petrol or diesel systems.

Cavitation or voids in the measured fluid are caused by a reduction in flow vis demand, which always lead to component failure be it a fuel pump, turbo or engine.

Under pressure
The last gauge in the kit was born from a simple brief to provide a simple tool to evaluate DPF and exhaust pressure increase.

Its requirements were a range of -1+1 bar, an 8mm/6mm tail hose, damped to smooth exhaust pressure pulse deviations.

ItÂ’s common to have DPF pressure transducer errors, and donÂ’t forget to check adaption or sensor offset serially. the same comments apply to all pressure measurements as PCM control adaption is now pretty much common to all pump systems.

First check the static engine value which should be 1000mb, starting the engine should not produce any increase in pressure. The max pressure on load should not exceed 200-250mb with the ideal a little lower, at approx. 3psi.

We also have a compression gauge modification which we use together with our Pico scope pressure kit for electronic measurement of real time compression engine running, a good subject the next topic.

Want to know more?
The experience and processes developed in our workshop are then built into all our training programmes , all subjects are covered, choice of tools, process and risk assessment form part of the programme , but the most valuable and unique asset is hands on experience over 40 years.

Contact Annette at ads for details 01772 201 597 or visit autoinform.co.uk

 

Frank Massey

 

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