AUTONET TV

Not-So-Common Sense (Sensor Failures)

So your vehicle won't start.  What's the first thing that comes to mind?  Battery dead? Starter motor worn out? Out of gas?  Well, those are all reasons that make sense.  But your vehicle may be refusing to start because one of its computers is being warned that to do so might damage it.  Here's how that works.

You have lots of computers in your vehicle.  They need to know the status of things so there are several sensors monitoring various things going on.  These sensors send information to the computers that adjust the fuel and air mixture so you don't waste fuel.  They know when things aren't quite right and prevent you from starting your engine if that's going to damage it. 

Other sensors make sure the coolant is the right temperature, check to see you are not polluting the air and make sure other electronic components are performing their tasks correctly.

Here's an example of a sensor doing its job.  Your engine needs oil to lubricate metal components so the friction doesn't damage them.  Your engine has an oil pressure sensor that tells a computer called the Electronic Control Unit (ECU) if things are good to go or if there's something wrong, maybe the oil pressure is too low to keep things lubricated.  If it is, it gives a signal for the vehicle not to start, protecting the engine. 

Of course, the sensors can go bad, too, with some of the same results.  And so someone has to figure out if it's the sensor that's failed or if it really has detected a problem.  That is the challenge for technicians with specialized equipment to decipher the signs.  If a bad sensor is found, it may need to be replaced.  Sometimes a thorough cleaning can do the trick.  In either case, your service facility can track down the problem and get you back on the road.  Makes sense, doesn't it?

McLearen Shell
3043 Centreville Road
Herndon, VA 20171
(703) 318-7744
http://www.mclearenshell.com

Losing Your Spark (Spark Plug Replacement)

When's the last time you thought about spark plugs? You probably don't remember.  That's because spark plugs usually last a long time and don't need much attention.  But they don't last forever, and when they start going bad, they'll send you a few clues.

• Vehicle is hard to start. 
• Fuel economy is going down
• Acceleration isn't what it used to be
• Engine runs roughly
• Check Engine light is on

There are many things that can cause those symptoms, so it's wise to head on over to your vehicle repair facility to have them look over your vehicle.  But the problem could be your spark plugs. They do wear out, not producing a strong enough spark to ignite your fuel the way they're designed to.  A closely related problem is failing spark plug wires, and a technician will test for both possibilities… and more. 

Your vehicle's manufacturer recommends changing wires and/or plugs at certain intervals.  Spark plugs are made out of different materials and some last far longer than others.  Ask your service advisor to let you know when yours should be changed.  Badly misfiring plugs can cause expensive damage to a vehicle's catalytic converter, so it's best to take care of them before that happens.  Replacing your spark plugs and/or wires is money well spent to have your vehicle running smoothly, dependably and efficiently.  

McLearen Shell
3043 Centreville Road
Herndon, VA 20171
(703) 318-7744
http://www.mclearenshell.com

Command Performance (Engine Air Filter)

The internal combustion engine in your vehicle counts on two things that mix together to be burned in the engine for power: fuel and air.  Both are important, of course.  If you run out of fuel, your engine won’t run at all.  Since there’s plenty of air around, you won’t run out of air, but you could feel your vehicle’s performance suffer if the engine air filter starts to get clogged. 

It's important that the air that enters your engine be free of dirt, dust, and debris to prevent damage to internal components.  That’s where the engine air filter comes in.  It prevents those particles from entering the engine, an important job that most people just take for granted.

After a while, your air filter will get dirty, which results in less air reaching the engine.  Modern fuel injected engines can adjust the amount of gas to mix with the air that is getting in, so your fuel economy won’t change significantly.  What will change is how well the engine performs, its acceleration.  In one test, a US Department of Energy study showed that a dirty air filter reduced a vehicle’s get-up-and-go by as much as 11 percent.  

The company that made your vehicle includes guidelines in your owner’s manual on how frequently that filter should be changed, and doing so will maintain your engine’s performance. If you drive in dusty, dirty areas or those with a lot of industrial pollution, we recommend you replace the engine air filter more frequently than the manufacturer’s recommendations.  

When you bring your vehicle to us for regular maintenance, we will routinely check several components, including your engine air filter, and recommend a change when we see signs it’s needed. It’s good for your engine, and you’ll enjoy the performance you expect.

McLearen Shell
3043 Centreville Road
Herndon, VA 20171
(703) 318-7744
http://www.mclearenshell.com

The Little Valve that Could (PCV Valve Replacement)

It's easy to get letters like PVC and PCV mixed up.  PVC is a plastic that's used in a lot of things, especially plumbing pipes.  And PCV is a valve that helps your engine burn off excess fumes rather than having them pollute our atmosphere. 

PCV stands for positive crankcase ventilation.  When your engine ignites gasoline in the cylinders, some of the gases produced make their way into the crankcase, where oil is held to lubricate the engine.  In earlier days, those gases would be vented out through a hose and go directly into the air.  It was a waste of gasoline (since about three-fourths of the gases were unburned fuel) and a nasty source of pollution.

So engineers devised a one-way valve that directed those gases back into the engine's air intake system to be burned again.  After a while, the PCV valve can get clogged up with gummy oil.  Not only does that reduce the recirculation of the gases, but it can also cause pressure in the crankcase to increase and possibly lead to an oil leak.

Signs your PCV valve has failed are oil leaks around the engine compartment or under your vehicle and poor engine performance. Your fuel economy will get worse. If you notice those signs, we can check your PCV valve. 

At the same time a technician inspects the PCV valve, they'll also check the vacuum hose that runs back to the air intake.  Plus, they'll make sure the vehicle doesn't have any other engine problems that might be contributing to your issues. 

Many technicians recommend replacing your PCV valve with each major tune-up, so you get ahead of any problems before they develop.  Now that you're an expert on PCV, it may be time to check out those PVC pipes in your bathroom!

McLearen Shell
3043 Centreville Road
Herndon, VA 20171
(703) 318-7744
http://www.mclearenshell.com