by Jim Kerr
Winter is fading quickly from memory and the smell of spring is in the air. Most vehicles have survived Canada’s harsh winter environment without problems, but with the lure of holiday weekends and cottages to open, many of us will be starting to think of longer trips ahead. Before heading out on the highway, or even for that drive back and forth to work, our vehicles should be checked out so wear caused by winter driving doesn’t leave them on the side of the road.
Winter driving usually means a lot of idling time for our vehicles. Extended warm up times and slower commutes because of poor road conditions take their toll on all vehicles. Exhaust systems don’t heat up and moisture rusts them from the inside out. Rutted roads pound suspensions, possibly damaging steering components. Brake calipers have corroded slides, causing brakes to drag and tires to wear. All of these problem areas need to be checked, but there is another automotive maintenance item that will soon be promoted by all the repair shops – Spring Tune-up Specials.
The word “Tune-up” means many things to people. Maybe it means simply changing sparkplugs, checking filters, and scanning for codes. It could also mean that everything from charging system analysis to injector flushing is done. This type of tune-up costs much more, but the benefits are higher too. Those extra tune-up procedures can either save money in fuel costs or extend the life of the vehicle, and maybe do both. When getting a tune-up for your vehicle, be sure to check exactly what the repair shop will do during the tune-up.
So what type of tune-up should we be looking for? Start with sparkplugs. Even though the auto manufacturers claim the sparkplugs in many vehicles are good for 160,000 km, we know that winter driving with its cold engine temperatures and rich fuel mixtures can foul plugs. Even one sparkplug firing intermittently will decrease fuel economy dramatically.
Misfire problems become more noticeable as outside temperatures warm up. Engines run hotter, the computer leans out fuel mixtures, and torque converters lock up easier under light throttle. High engine loads and lean fuel mixtures are prime conditions for a misfire, and this problem usually shows up at about 80 kph as a surge or hesitation. Thousands of dollars have been spent fixing “transmission chuggles” when the problem was really ignition related.
The high voltage in modern ignition systems and wide plug gaps combine to find the smallest electrical leak in plug wire insulation. If one bad wire is causing a misfire, you can be sure the others are not far behind, so change them too.
Oxygen sensors are often overlooked during a tune-up. They also become fouled by rich mixtures and their performance slowly degrades, causing a fuel economy decrease. Scan tools may show the sensor jumping rich to lean, but sluggish response rates mean it is time for a new sensor. New sensors can improve fuel economy dramatically so changing a high mileage sensor makes good sense.
Be careful to get the correct part if you install a replacement sensor at home. There are different calibrations for oxygen sensors depending upon if they mount in front or behind the converter. They may fit, but that doesn’t mean they are working properly.
Exhaust leaks anywhere in front of the converter can trick oxygen sensors into telling the computer to add fuel. An exhaust system inspection isn’t often thought of as a tune-up procedure, but a missed exhaust leak will cause poor fuel economy.
Electrical system grounds cause more problems than we can imagine. Road salt and moisture in the winter quickly causes corrosion, so a couple minutes re-tightening body and engine grounds can prevent many driveability problems.
Fuel injectors spray fuel in a fine mist so it atomises quickly in the combustion chambers. Deposits and gum in the injector tip cause irregular spray patterns that can decrease fuel economy, cause hard starting, and may create surges or misfires. Normally injector cleaning is not part of a tune-up, but extended idling times in the winter tend to cause more sticking injector problems, so doing this as an add-on to the tune-up can improve economy and driveability.
Tune-ups cost money, but at the price of fuel today, even a slight improvement in fuel economy will repay the cost of that tune-up quickly.