Two weeks ago I insinuated vehicles still need tune ups. Even if there is no such thing anymore. Like I said, most owner’s manuals make no reference to a tune up.
So if you go in asking for a tune up what are you going to get, an Italian tune up? I must say an Italian tune up has its merits. After a long cold winter where your engine spent more time idling than singing at the higher end of your tachometer has probably left a little excess carbon in the engine. Some good full throttle runs to redline on the old tachometer would probably clean some of that up. There are better more effective ways to remove carbon though.
Your manual says you don’t need new spark plugs until 160 000 km and you are only at 50 000 km now. A few articles ago I suggested there are no adjustments anymore. You are starting to think that tune up thing is just a bunch of smoke and mirrors. Not so!
A modern day tune up starts with a road test. It still requires some touch and feel. Your technician has to have a feel for driving and engine performance. On this same road test a real professional will take a scan tool. The scan tool communicates with the engine control computer. Your engine controller has a component to it that is constantly running diagnostic tests. Any failed tests will set a diagnostic code.
The scan tool will query for these codes. Not all codes turn the check engine light on so the driver will be unaware of these problems. The check engine light does not have to come on unless the problem will increase emissions.
Many vehicles have inoperative knock sensors that result in reduced engine performance. Turbocharged or supercharged engines can operate in reduced power modes when they are unable to control boost pressure properly.
Many times these problems do not alert the driver to their existence. Knock sensor issues are particularly hard to notice but fixing them is worth some percentage points in increased mileage and horsepower.
Loss of boost pressure is usually more apparent to the driver but the mechanic will know right away when the scan tool produces a diagnostic code.
Codes are definite indicators of an existing problem but live data analysis also available from the scan tool can flush out some other issues.
A sharp technician can identify a dirty throttle body, a dirty mass air flow sensor, a restricted fuel filter, a failing fuel pump, a slow oxygen sensor, or failing air fuel ratio sensor.
Scan data analysis can provide this information that even the most sensitive driver could not pick out.
Once the analysis is done the tune up can be accomplished. Throttle bodies can be cleaned, mass air flow sensors can be cleaned, fuel filters or fuel pumps replaced, oxygen sensors or air fuel ratio sensors replaced.
A tune up will thus as ever make your vehicle run better. Admittedly it may be tougher to recognize the benefits but if you track your fuel mileage or measure the power your vehicle produces you will be suitably impressed. The tune up lives on!
Trail’s Ron Nutini is a licensed automotive technician and graduate of mechanical engineering from UBC. He will write every other Thursday. E-mail: firstname.lastname@example.org