Scan Tools: Solving the Diagnostic Puzzle

Scan Tools: Solving the Diagnostic Puzzle

Scan Tools Main“The fact is, the most expensive tool may not be the best tool for you. It depends on what vehicles you work on and what you want out of the tool.”
– Dwayne Myers, Dynamic Automotive, Frederick, MD

If a 1996 or newer vehicle with OBD II rolls into your shop with a Check Engine light on (aka the malfunction indicator lamp or MIL), it is probably because the power control module (PCM) is receiving data indicating that all is not well. Whether the light comes on intermittently or remains steady, the vehicle cannot pass the state emissions test until the technician determines the source of the problem and resolves the issue. On such occasions, a tech normally reaches for a scan tool for diagnostic help.

An automotive scan tool is essential for performing advanced on-board diagnostics. It enables technicians to access a vehicle’s OBD system in order to not only read the diagnostic trouble codes (DTCs) – which a simple code reader or scanner can also do – but, more importantly, can also perform a variety of system self-checks to determine the source of the trouble. This may include, but is not limited to, checking the operation of the fuel pump, fuel injectors, idle speed control motor or solenoid, EGR solenoid, A/C compressor clutch, cooling fans, EVAP purge controls, cylinder balance testing, misfire graphing and much more.

As cars have become more and more sophisticated, so have the scan tools to diagnose and repair their complex on-board electronics. Many manufacturers offer a variety of models at various price points with a broad range of features to suit the level of functionality desired and the mix of makes and models that a shop services. It is not unusual, therefore, for a shop to own several scan tools with different diagnostic capabilities. If a shop works on a single vehicle make, it has the option to purchase a dealer-specific tool. Those are usually expensive, but the need for factory-based scan tools is becoming increasingly necessary for most popular car lines because programming and network issues are starting to require them. One hopes aftermarket tool manufacturers will keep up with this growing need.

While a do-it-yourselfer (DIYer) can function with a simpler tool that offers fewer functions, a scan tool for professional technicians needs to incorporate many more features including the important bi-directional capability or two-way communication. Bi-directional capability allows a technician to “talk back” to the system. In other words, one can not only learn what is going on at the other end, but also can activate certain functions at the same time, such as turn on the ABS motor in the car, pop the trunk open electronically or turn on the headlights.

Scan Tools 2Return On Investment
The price of a top quality scan tool runs high, but it is usually well worth the cost in the long run.
“Cost is always a factor, but to me it is never the first,” said Dwayne Myers of Dynamic Automotive in Frederick, MD. “The fact is, the most expensive tool may not be the best tool for you. It depends on what vehicles you work on and what you want out of the tool. You will need to invest money in purchasing a quality scan tool, but you must also invest time in finding the tool that is best for you.”

Features To Look For
Some of the features that you may want to look into before you invest in a scan tool, are: speed; diagnostic capability; full scan functionality; breadth of vehicle coverage with OE-level access to Asian, European and domestic applications; bi-directional capability; software updatability; and module coding and re-flashing capability with vehicle-specific information and VIN number.

Scan Tools 3Look for a model that is fast – one that is able to decode a VIN and communicate with all modules and report DTCs in a couple of seconds. Also, be sure it is accurate and easy-to-use with subscription-based software updates that can be downloaded quickly from the Internet and one that can be connected via Bluetooth or USB with ultra-fast, real-time streaming live data with the ability to graph different functions.

Scan tools can be desktop-, laptop-, tablet- or smartphone-based. Most scan tools use the PC or Android system, but there are also those that run on the iOS operating system. Some manufacturers offer a lifetime warranty on the hardware.
Scan tool tablets are usually drop-tested and some models are also designed to be water-proof. Depending on the model you select, it may come with a high-resolution IPS touch screen, a high-resolution camera with still and video capabilities and reduced screen-to-screen wait times.

Some scan tools feature customer remote diagnostic capability. This means that a technician can analyze a customer’s vehicle data remotely – miles away from the shop. A good scan tool may also alert a technician to web-based repair data via a website service or a technician forum, or even perform a Google search within a diagnostic session.

Scan Tools 4Whatever make or model you ultimately choose, make sure that the software on your scan tool is updated – refresh rates on data is very important.

“If you want to be considered one of the top shops in your area,” Myers concluded, “you must have the appropriate tools to do the job. For accurate diagnostics, for instance, you must have good information and to get this information, you need scan tools. I say that in the plural because no two tools are exactly the same and, I believe, you need more than one brand to get ‘good’ information. Integrity of the data is critical for a proper diagnosis. Nothing is worse than getting bad information; it costs you money, time and your reputation.”

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Back in the days when most

Back in the days when most ­engines had cast iron blocks, heads and manifolds, the intake manifold could be easily sealed with simple and relatively inexpensive die cut fiber-faced metal gaskets (solid or perforated core). Sealer was usually required to ensure a leak-free installation.   But in the late 1980s and early 1990s, fuel systems and manifolds began to change. Multiport fuel injection meant the intake manifold no longer had to flow an air/fuel mixture, only air.   This gave engine designers more ­freedom to optimize airflow. Manifolds became more complex, with long curving runners and intricate plenums engineered to improve throttle response and low speed torque. Plastic became a popular material for casting manifolds due to its low weight and cost.   Some were also fitted with tuning valves that could reroute the air inside the manifold to change air velocity and flow according to engine speed and load. 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If this area is eroded or pitted, the intake manifold gaskets may not seal properly when the engine is assembled.   In some cases, it may be possible to clean up the mating surface on a pitted head by lightly resurfacing the intake port side of the head. Pits can also be filled and sealed with high temperature epoxy fillers, then sanded or machined flat to restore a smooth, flat surface. If the erosion is severe, it might even be necessary to build up the damaged area by TIG welding the head or replacing it altogether with a new or salvage casting.   According to one aftermarket gasket manufacturer, the recommended surface finish for the intake manifold and cylinder head mating surfaces should ideally be 30 to 60 microinches Ra (Roughness Average). Another gasket manufacturer said anything from 20 to 80 Ra should be good enough.   Unlike the super-smooth surface finish that’s usually required for late-model MLS head gaskets (20 Ra or less), the surface finish for most intake manifold gaskets isn’t as critical. Even so, it must be smooth, flat and clean, with minimal pitting and waviness.   If the intake manifold or intake ports on the head are milled at too high a feed rate, it can leave an undulating wavy finish with ridges and valleys that can be difficult to seal. This may result in coolant or vacuum leaks, as well as premature failure of the intake manifold gasket sealing beads.   Overall flatness on both mating surfaces should also be checked with a straightedge and feeler gauge. Flatness should be 0.003” or less on the mating face of the intake manifold and cylinder head intake ports on V6 engines, and it should be 0.004” or less on a V8 or straight six.   Equally important, the intake manifold and head surfaces must be clean (no grease, oil or coolant film) and dry. RTV, other sealants or adhesives should not be used around the coolant or intake ports on carrier-style gaskets. The only place RTV silicone may be required is to seal the area where the ends of the intake manifold gaskets mate with the end strip seals on the block under the intake manifold or valley cover.   It’s also essential that the threads for the intake manifold bolts in the head be clean and undamaged, as this can affect clamping torque. New intake manifold bolts are recommended. But if you must reuse the old bolts, make sure the threads are clean and undamaged. Also, follow the recommended torque procedure when tightening down the intake manifold bolts and make sure it is the latest procedure as the original procedure and torque specs may have been revised.   If the intake manifold gasket does not make a tight seal around the coolant ports, it may leak coolant into the crankcase. If it fails to seal tightly around the intake ports, it may allow vacuum leaks that upset the air/fuel mixture and cause idle and driveability issues. Testing For Air Leaks Even the smallest leak in an intake manifold can cause a fuel trim problem. Finding a leak can be time consuming using your eyes and ears.    Intake manifold air leaks will suck in air, not expel it. What is sucked in will influence the fuel mixture and impact engine and emissions systems.    A smoke machine allows you to diagnose multiple leaks in less time compared to other ­methods. A smoke machine can pressurize the intake manifold and put smoke or vapor into the system. If there is a leak, you will see smoke come out.    Connect the smoke machine to a vacuum port like the supply line to the brake booster. Make sure to block the throttle body with the right sized plug. Also, block off the PCV system.    Leaking injector seals can cause lean and misfire codes. Conventional testing methods often involve flammable gases or putting thick oils on the seals and looking for a change in rpms. But this test can’t be performed on engines where the intake manifold restricts access. Smoke machines can help spot these leaks without any disassembly.    Smoke coming from the oil filler or PCV system on an engine that is not misfiring could mean the bottom of the manifold is leaking or has cracked. It can also indicate worn valve guides or seals.    Coolant Leaks Coolant does not magically disappear; it has to go somewhere. External leaks can be seen with the naked eye or by using dyes. Internal leaks can find their way into the combustion chamber or the oil. 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