How can you test what you can't see?

John Batten shows how you can never be complacent about skills, as you always need to be ready for what might come through the door

By John Batten | Published:  30 April, 2018

Life as a business owner can often be as challenging as it is rewarding, in fact overcoming these challenges is half of the reward for many, especially when it comes to accurately diagnosing the undiagnosable.
    
Many businesses build a reputation locally on the fact they’re able to find faults that others can’t. This acts as a point of differentiation, which is great. Developing this reputation in your locale can pays dividends, as customers become less price focused when they know why you’re different to your competition.
    
What a great place to be. Your customers love you because you’re effective in your diagnosis and you get paid well for doing this. What’s not to like about that? Not a lot!

Sounds great but…  
 
If it were that easy, everyone would be doing it. Easy? Definitely not, but then anything worth achieving never is. Here’s the deal though – It’s not difficult either, although it does take some deliberate thought on the part of the business owner. The kind of technical success that’s required for a reputation like this is within the grasp of all garage owners; It just takes the commitment to change and a willingness to plan for the change required.

The owner is clearly responsible for the health and continuing success of their business, but with so much demand on their time creating a technical team to differentiate your business from your competition is not always at the forefront of their mind.

The best time to plant a tree…
Was 20 years ago. The second best time is now. As proverbs go that one hits the mark when it comes to developing anyone within your business. The question is, where to start?
    
Skills analysis is a good a place as any. What skills do your technical team currently possess? Do you have a team of technical superheroes today and just need to turn on the marketing tap to increase your bottom line numbers? Or do you have a hero in the making and need to take a look at the training required before you buy them a cape? If you’ve a hero in the making then that’s great! There’s nothing more satisfying for a technician and the business owner when they embark together on a symbiotic journey of development. The technician will feel invested in and the owner will have a stronger team and be able to promote their newfound skills increasing efficiency and profit. A win-win for everyone!
    
So you’ve got your training plan in place and the technical skills of your team are moving in the right direction. Time to put your feet back up on the desk? Not quite. Continued success means that not only do you need to be able to efficiently repair what’s in your workshop today, but see what’s coming over the hill and ensure you have the skills and equipment for tomorrows car park.

I’m sure you’ve heard diesel fuel being called into question as a long term option for powering our vehicles and that we’ll all be driving dodgems (or some other electric vehicle) as the future of motoring. But is there an alternative that has both a foot in today and an eye on tomorrow? Oh yes, I’d almost forgotten… It’s petrol. More specifically gasoline direct injection (GDi).

The ‘new old’ technology
GDi has been with us for some time and in reasonable quantities since the early noughties. This means there are bucket loads of these vehicles in your workshops daily. Not only that, but manufacturers are looking at the benefits of taking rail pressure in excess of 500 bar and how this may help with emission reduction. What does this mean for you? Well. If your not sure how to effectively diagnose these vehicles then there’s no better time to learn. Plus it’s probably here for some time to come. With that in mind it shouldn’t come as a surprise that my technical article this month is a 2L GDi Audi A3.

No time to hesitate
The customer complaint on this vehicle was a rough idle and hesitant pick up on light throttle. Following my own mantra, I started Johnny’s 15-step diagnostic process with a thorough questioning of the client whilst experiencing the issue with them. It was indeed ‘stumbly’ (believe it or not that is a technical term – in my world anyway) and I followed this with a look at fault codes and inspected serial data. There was nothing to write home about here, neither was there with the tests for mechanical integrity or ignition diagnosis. So where does that leave us? Just fuelling.

Under pressure
With just fuelling left as the option for our hesitation low and high-pressure systems were evaluated and again no fault found, that just left injection quality or quantity.
    
GDi Injectors differ from manifold injectors not only in their position (GDi injecting straight into the cylinder) but also in their electrical characteristics. The high current driver (10 Amps, see figure 1) enables fast multiple injections not dissimilar to that of solenoid diesel injectors. All injectors were inspected electrically and again no fault found. We were fast running out of test options for fuelling... What to do?

How can you test what you can’t see?
We had seen similar issues before and figured I’d try and identify a dribbly injector (there I go getting all technical again) prior to its removal from the cylinder. We ran the engine and stopped it, isolated the breather system and removed a spark plug, then tested for HCs in each cylinder waiting for a drip and a rise in HCs. What did we find? Nada, Zilch, Nothing! There was nothing for it the injectors would have to come out and be tested.    
    
It just so happens were fortunate enough to have a Carbon Zapp test bench in the training center. This gives us the capability to test GDi injectors at high pressure. It’s a cool piece of tech that runs the injector through an automated test plan, giving a pass/fail report on the injection characteristics. After testing each injector I was delighted to find one
of these was defective and the fault found.
    
If you’d like to see the injector being bench tested then head over to www.autoiq.co.uk/blog where you can watch a video. So there we go another car fixed, and I’m sure this happens in your workshop on a daily basis. But here’s a question for you: Do you have a program of technical development to help your team work efficiently? And can you differentiate your business from those around you? If it’s a yes to both then brilliant, you’re set for the future! If not then give me a call at Auto iQ on 01604 328500 and I’ll be only too pleased to help your business develop a plan for your continued success.




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    My life as a business owner, trainer and technician is an interesting one. I was recently spending some time with a client after a course just shooting the breeze. You know the kind of thing, a cuppa, a cake and an hour just putting the world
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    Wading through treacle
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    The recipe for success
    As with most things in life there are essential ingredients. With the right ingredients you’ll successfully avoid the diagnostic treacle swamp and swap this for a faster and more enjoyable repair experience.
        
    “What’s this recipe?” I hear you cry. It has six elements that when bought together produce truly remarkable results. They are;

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    Access
    The key, as it has been in the past, is access. In this case, the right to be able to repair vehicles. Think that’s all sorted? Perhaps not:  “The rise of the electric cars and vehicles is something that could hit the automotive aftermarket hard – in particular, independent garages.

    “Many, if not all, electric vehicles invalidate their manufacturer warranty if essential work is carried out on the electrical systems by someone other than the main dealer. What’s more, many cars with batteries, such as the Mitsubishi Outlander PHEV, have warranties on the electrical components lasting up to ten years.

    “Having no choice but to use the main dealer for a full decade shows just why independent workshops will have fewer vehicles coming through the doors in the years ahead.”

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  • Inject some knowledge  

    At the heart of fuel delivery is the injector. If there is a single focus point that has helped reduce emissions and boost performance it’s the injector. Despite this, we don’t pay it enough attention, and I include myself in this critique. Let me qualify this by asking a rhetorical question; How many of you have injector bench test capability?

    I do, but freely admit to not giving it a more prominent position in fault diagnosis. I am going to expand later just how intrusive testing should be conducted. To begin, a short trip down memory lane won’t do any harm in understanding basic problems.
        
    Injector problems started in earnest when lead was removed from gasoline. The Nissan 1.8 turbo and Austin Montego 2.0efi were two of the most problematic examples. Both used 15ohm single event saturated triggering with approximately 1-amp peak current. This was back in the days when we were not measuring current nor did we have an injector bench.
    All the diagnostic evidence came from the 4-gas analyser. CO and O2 should balance at approximately  0.5%, as this will achieve a near perfect lambda 1 ratio, 50-100, CO2 at its highest at around 17-18%.
        
    A lot has happened since then. The key to ideal fuelling is in reducing the lag or dead time in injector response to PCM control. As engine power increased and turbos became almost mandatory, more fuel was required. To achieve these aims, opening times were increased to a point where they were in danger of colliding at high engine RPM. We are still talking port injection here, fuel pressures crept up to four-bar and high flow injectors started to be introduced.

    Current ramping also changed to peak and hold with peak values of around 4-amps. For the time being things stabilised, with little or no obvious common injector problems. The next challenge manufacturers faced was to reduce the internal mass of the injector components. In plain English they got smaller, lighter, less robust, and with lead free legislation less reliable. Remember Fiat iaw injectors?

    Precise control
    As EU emission rules became more stringent, the need for even more precise control was inevitable, and along came direct high-pressure injection. Lets explore the variables of fuel transportation, variable delivery pressure 50-200bar, multiple injector strikes and adjustable delivery timing. Peak current now reached 10-amps and pwm switching became commonplace.
    We now have gasoline injection that more  closely resembles diesel injection protocols. They also bring similar problems. Fuel is no longer delivered through the inlet port, leading to a build up of carbon behind the valves. This effect, the critical swirl in the cylinder, is essential for complete combustion. Filtration and fuel quality are now major considerations for reliability.

    Hostile environments and anomolies
    Injectors are now mounted in a more hostile environment, more pressure, more heat, more tip carbon. So, the need for testing and cleaning has come full circle from the lead-free era. A major problem here is the stress caused to the injector body by techs not using the correct removal tool.

    Remember the comments on lighter internal mass; This means than bending stresses during removal leads to intermittent combustion anomalies. I do love that word, it more accurately describes incomplete combustion, often without any credible serial fault data.

    New fault phenomena
    Now let’s notch it up a bit and introduce some new fault phenomena. The internals are so light they can suffer mechanical failure, and the closure spring can break. The internal filter basket has been moved to a more central position, resulting in inaccessibility for replacement.

  • It CAN be done! 

    We all remember certain jobs which test our nerve but ultimately serve to strengthen our capabilities. Proper learning experiences so to speak. Unsurprisingly, these memorable jobs tend to occur when tackling novel technologies or environments which, by their nature, can be unsettling.
        
    Some time ago a customer arrived with a MINI having persistent warning lights, instrumentation faults and bearing a new instrument cluster and engine control unit. Mindful that the expensive repair history must have included some seriously ‘in-depth’ diagnosis, I decided to get involved and see what I could do to fix the issues.

    Ruling out
    A system scan reported various powertrain CAN faults in the engine, ABS and instrument cluster control units, indicating a system-wide communication issue but with no systematic patterns to help isolate the fault. The MINI had a separate diagnostic bus, which thankfully permitted scan tool communication in the presence of a CAN fault. However, CAN access was not available on the diagnostic connector to aid recording of the signals. Instead, an oscilloscope was connected to the engine control unit (Figure 1) to reveal that the wires were unlikely to have shorted together, to Earth, nor to +5V, as the signals from the engine control unit were almost ideal. The fault was more likely due to circuit integrity. After powering down the CAN this was confirmed, as a 120 Ohm resistance was measured between the high and low lines (around 60 Ohms was expected).
        
    Subsequently, the customer was called with an update and to authorise further expenditure. The next stage involved pulling the car apart to fully check the wiring and control modules. Plainly, it was unwelcome news.

    Added pressures
    When conscious that the meter is running, doubt can creep in and you find yourself asking if a wiring fault is too simple, alongside other related questions. This was not a good time for misinformation. The resources available (course notes and workshop information) identified the MINI’s engine control and ABS units as each having a 120 Ohm terminating resistor between the CAN pins. Subsequent measurements determined a resistance of 120 Ohms on the engine control unit but many kilohms on the ABS control unit. Was it faulty? Nerves started to fray. Following a thought process akin to James Dillon's mantra "what would you test next if the part you had just fitted did not cure the fault," basic procedures were recalled.
        
    Firstly, on this MINI the terminating resistors actually were in the engine and instrument control modules (all were fine). Next, a series of continuity tests isolated an open circuit on the CAN-H line between the ABS and engine control units. It was located in a well-protected and tiny portion of wire, equidistant between the terminating connectors. Figure 2 shows the damage.
        
    The process demonstrated to me how, during stressful situations, it is worth trying to adhere to basic procedures as faults are often straightforward. As it turns out, this would have been good advice for the recent Top Technician practical tasks, which proved a very similar experience – I wish I had listened! For anyone thinking of entering, I highly recommend it.


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