2014 Editions Archives - UnderhoodService
Turbocharged Technology

Utilizing electronically controlled wastegates and bypass valves With the ability to increase fuel economy by up to 20% on gas vehicles and up to 40% on diesel vehicles, manufacturers have resorted to turbochargers to compensate for lowered engine displacement. Additionally, the improvements on turbocharging technology have increased the number of turbocharged vehicles on American roads.

Volumetric Efficiency Diagnostics

A few years ago, I obtained an OBDII scan tool/dynamometer simulation/calculation program that can graph volumetric efficiency (VE) over rpms. Using real world vehicles, and no useful instructions, I devised a test sequence that allows a technician to see things another way. What is Volumetric Efficiency? Let’s keep this simple to start. An engine is

Oil-Related Engine Codes for VVT Engines

Variable valve timing is becoming a standard system on most late-model engines because it offers higher performance from a smaller displacement engine at higher rpms. Oil plays a larger role in VVT systems. They need engine oil not only for lubrication, but also to actuate the camshafts to change the profile of the lobes. Oil

VVT camshaft adjustment
Harmonic Dampeners: Why They Fail, What to Look For

Every time a cylinder fires, the crankshaft speeds up a very small amount for a short period of time. It is then slowed down as the next cylinder in the firing order compresses air and fuel for the next combustion event. The speeding up and slowing down of the crankshaft produces torsional vibration or twisting

Harmonic Dampener
Be Careful When Replacing That Diesel Air Filter

Modern passenger and light-duty diesels with ECMs have mass airflow sensors and precisely control fuel ­delivery. Key to the efficiency and lifespan of the diesel engine is the diesel air filter. A restricted air filter will not affect fuel economy but will drastically affect power output. We asked prominent filter manufacturers for some diesel air

diesel air filter replacement gauge
Making Money with Mode $06

Nothing is more frustrating than “fixing” a customer’s vehicle and then have it come back a few days or weeks later with the check engine light on and the same fault code or a new fault code. You look bad, lose your customer’s confidence in your ability to fix their vehicle, and in states that

Mode 06 diagnostics
Ford Reflash: Setting Up Your PC

You’ve just finished up a job on a Ford vehicle, and you’re about to try and start it up. However, it needs programmed first. You’ve decided to use a J2534 tool, but there are certain things you’ll need to consider ­before purchasing that subscription at www.motorcraftservice.com. Choosing a PC The PC you choose for reflashing

Fuel Line Replacement: The Why and How

If you live in a state that doesn’t get snow, you can stop reading right now. If you live in the Snow Belt, you are about a month away from snow and ice. It’s not the adverse driving conditions that should scare you or your customers, it’s the trucks with large white tanks strapped to

Fuel line hose
Case Study: 1996 GMC 1500 with no temperature control

• No A/C, no vent control, no temperature control • A/C and recirculation buttons will not light up • All new components, including compressor and control head Cars with a little age on them can be temperamental when diagnosing what might seem at first to be an easy problem. This 1996 GMC had already gone

Chevy AC electrical case study
Toughest Spark Plug Changes

We have all been there before: scratched arms, busted knuckles and an aching back caused by a difficult spark plug replacement job. If you think they are getting tougher every year, you are right. Every new engine design is putting the plugs deeper in the heads, and items like intake manifolds are getting in the

Toughest spark plug jobs
Improving the Head Gaskets, Fasteners Relationship

The relationship between head gaskets and head bolts is an intimate one. The clamping load applied by the head bolts is what allows the head gasket to maintain its seal. For this marriage to last, there has to be constant tension – not too much, otherwise the bolts may stretch or break, and not too

head gaskets and fasteners
Driveability Diagnostics and Direct Injection

Direct injection is becoming standard on more and more late-model vehicles. These systems can be a diagnostic challenge, but with the right foundation, problems can be solved profitably. Years ago, all a low-level technician needed to diagnose a fuel problem was a set of “noid lights,” a fuel pressure gauge and maybe a meter. These

Direct Injection Fuel System