When and why should I tune up my car?
Since 1981, cars have been getting very sophisticated. On board computer controls the timing and delivery of spark and fuel depending on the conditions (uphill or downhill, cold or hot). Many car owners manuals recommend the plugs be replaced at 30,000 mile intervals. I believe sooner is better. I change the plugs in my own cars every 20,000 to 25,000 miles. Statistics show that the loss of one mile per gallon over a year's period will equal between $40 and $80. Therefore, "you can pay me now...."
Take a car that gets 19 mpg and travels 15,000 miles a year. At 19 mpg, the car will use 790 gallons of gas at $1.50 a gallon, which will equal $1185.00 in annual fuel costs. At 18 mpg, it'll need 833 gallons that will cost $1249.50. So that one-mile per gallon loss will cost you $64.50. A single misfiring spark plug will affect the gas mileage much more than just one-mile per gallon. A four-cylinder engine with one misfiring spark plug stands to lose up to 25% of its available power. At 60 miles per hour, most engines are running about 2200 rpm. That's 36 revolutions a second. Each second that each spark plug is firing that 18 times. Over a period of one hour at 60 mph, each plug will fire 64,800 times.
If you own a newer car with a distributorless ignition system, take the above figure of 64,800 and times it by two, which would equal 129,600 times an hour your spark plugs are firing, at 60 miles per hour.
If spark plugs in your car fire over a million times a week, doesn't a $55 or so tune up with new plugs once a year or so sound like a good investment?
Does the make of spark plugs make any difference?
I have used and sold Autolite (Which is the first and original copper core plug.) spark plugs for the last 25 years. At our shop, We have the capability to measure how much electricity or KV is going to the spark plug. We can also measure how much electricity is needed to maintain the "burn" or bridge. Last, We can measure how long in milliseconds the spark plug maintains the spark or burn. Many times in the past, We have compared Autolite to others and found Autolite to out perform all others we've tested.
Why Are There Many Different Types of Spark Plugs?
Spark plugs need 5,000 to 40,000 volts from the ignition coil before a spark will jump across its electrode gap. It takes a lot of volts to push the spark across the gap because air doesn't conduct electricity unless it is ionized first. The spark jumps from center electrode to side ground electrode.
The reason why a plug fires from center electrode to side ground electrode, instead of vice versa, is because it's easier for a spark to originate at a hot electrode than a cooler one.
The center electrode runs much hotter than the side electrode because the center electrode is encased in ceramic (a good insulator of heat as well as electricity). This slows down heat transfer from center electrode to cylinder head.
If ignition polarity is reversed, it can take up to 40% more firing voltage to send the spark from ground electrode to center electrode. The result can be misfiring under load and poor engine performance.
Keeping the center electrode hot also helps burn off fuel and oil deposits that form on the insulator tip. Deposits can conduct voltage away from the gap causing the plug to misfire, so keeping the center electrode hot helps prevent fouling.
If the plug is too hot for the application, it can become a source of pre-ignition. If the plug is too cold, it can experience fouling problems.
The operating temperature of a spark plug depends on a number of variables. The two most influential are cylinder head temperature and the relative richness or leanness of the fuel mixture. Given such variables, it is impossible to have a single spark plug that would work well in every application, even if thread sizes and reach were standardized.
Heat range is determined by several design features, one of which is the distance heat must travel from center electrode tip to the plug's shell.
A plug with a short ceramic insulator between electrode tip and shell runs cooler than one with a long nose insulator.
A cold plug is good for high speed, high load operation because it sheds heat quickly and is less likely to overheat and cause pre-ignition.
Colder heat ranges are used most often in high performance and turbocharged engines.
For short-trip, stop-and-go driving, a cold plug may not run hot enough to keep itself clean. A hotter heat range plug may be needed to resist fouling.
For sustained high speed or high load running, a hotter plug may become too hot and cause pre ignition. The trick is to use a plug hot enough to prevent fouling yet cold enough so there is no danger of pre-ignition.
One way to extend or broaden the heat range of a spark plug is to extend the tip of the plug further into the combustion chamber. The longer insulator makes the tip run hotter for better self -cleaning at low speeds and light loads. It also exposes the tip to more of the incoming air/fuel mixture, keeping it from overheating at high speeds and loads. An extended tip spark plug typically has a much broader heat range than a standard spark plug.
Another way to increase heat range is to use a center electrode with a copper core. Copper is an excellent conductor of both heat and electricity. With a copper core center electrode, heat is carried away from the plug tip through the electrode during high speed, high load operation. This allows the plug to dissipate heat more quickly like a colder plug, yet stay hot enough to burn off fouling deposits.
Because of the increased heat range copper core plugs offer, one plug can be used in applications formerly requiring several different plugs with narrower heat ranges.
The use of a platinum or gold palladium center electrode is another design innovation that improves fouling resistance while greatly extending plug life. The special alloy at the tip of the center electrode is more wear and corrosion resistant than standard electrode metal. It allows the use of a longer insulator, helping plugs reach a self-cleaning temperature of 750°F in only a few seconds.
Spark plug manufacturers avoid making specific mileage claims for such premium plugs, but many experts say the plugs will often last up to 60,000 miles. Other benefits include better cold starting, less cold fouling, and improved operation during both stop and go and highway driving. These plugs are considerably more expensive than standard plugs.
Time for a Tune-up?
Time to Try MotorVac
Do the fuel injectors need tune-ups?
Until 1995 I always said no. Then A representative from Snap on Tools showed me a MotorVac Machine. We had a 1994 Ford Escort in the shop that had been to the dealer a number of times for the same problem. It had a miss at idle. We diagnosed it as a bad injector. The Snap on Tools representative asked us to try the MotorVac before replacing the injector. We did and when the job was done for a third of the original quoted price, and We acquired a happy new customer and a new Motorvac machine. They retail for around $5500 so you won't find it in most shops. I recommend cleaning them every 10,000 miles 0r 12 months. The price of a cleaning ranges from $80 to $150. I wouldn't have my shop without one.
This MotorVac machine cleans the air plenum, throttle body and plates, air bypass valve, injectors, carburetors, intake valves, combustion chambers, oxygen sensor and catalytic converters...without having to remove any engine components. A CarbonClean system cleans the entire air intake, fuel system and exhaust system, fuel rail and the injector screens. It is the only fuel injector cleaner that does this. I call it "god 2" (with a lower g). It never fails to amaze me, and it comes with a "money back guarantee"!
I've compared it to other machines and injector cleaners and theirs don't come close. The additives that are sold to “clean injectors by adding to the gas” only bring all the junk to the injectors. Leave the junk in your tank just clean the injectors.
The MCS245 is the first gasoline engine system of its kind to clean the entire fuel system. When used with the proprietary MotorVac CarbonClean Fuel System cleaning detergents, the MCS245 cleans the air plenum, throttle body and plates, air bypass valve, injectors, carburetors, intake valves, combustion chambers, oxygen sensor and catalytic converters...without having to remove any engine components. A CarbonClean system cleans the entire air intake, fuel system and exhaust system.
A MotorVac CarbonClean service will help your engine function more efficiently by unclogging accumulated carbon deposits from fuel injectors and other engine components.
What Should A "Complete" Tune-up Include?
Electronic ignition, computerized engine controls, and electronic fuel injection have eliminated many adjustments that were once part of a "traditional" tune-up. Most would agree that a tune-up today is a preventive maintenance service and engine performance check.
Call it what you will, a complete tune-up should combine elements of preventive maintenance, adjustment and performance analysis. One of the main reasons people bring a vehicle in for a tune-up is because they are experiencing some kind of drivability problem.
Things like hard starting, stalling, hesitation, misfiring, poor fuel economy, or lack of power are seldom cured by anew set of spark plugs and a few turns of a screwdriver. Every tune-up should include a comprehensive performance check to verify that no drivability problems or trouble codes exist.
Another item that should be included is an emissions check. Thirty-five states now have some type of annual vehicle emissions inspection program, and all but two include a tailpipe emissions check. Most mechanics will check EGR valve operation, the PCV valve, and make a visual inspection of other emission control components and plumbing. But unless an actual emissions performance check is made at the tailpipe, there is no way to know whether or not the vehicle will meet applicable emission standards. An emissions check is a must.
Taking into account longer service intervals and reduced maintenance requirements of today's vehicles, a tune-up is probably only necessary every 30,000 miles, or once every two to three years. This is altered when a drivability or emissions problem arises that requires diagnosis and repair.
The best guide to tune-up frequency is probably the recommended spark plug replacement interval in a vehicle's owners manual.
Our list that should be included in a "complete" tune-up include:
Replace spark plugs
Check distributor cap (replace if necessary)
Check timing (adjust if necessary)
Check ignition wires (replace if necessary)
Check ignition performance (firing voltage and ignition patterns)
Check idle speed (adjust if necessary)
Check choke (carburetor engines)
Clean fuel injectors
Check compression and/or power balance (identifies bad fuel injectors as well as compression problems)
Check manifold intake vacuum (reveals exhaust restrictions)
Check battery/charging voltage
Check exhaust emissions (verifies fuel mixture, ignition performance and emissions performance)
Check vehicle computer for trouble codes
Install new air filter
Replace fuel filter
Replace PCV valve
Check all emission controls (EGR valve, air pump, etc. )
Check all vital fluid levels (engine oil, transmission fluid, coolant, brakes, power steering)
Check belts and hoses
Check safety items such as lights, wipers, tires (including inflation pressure), horn, etc.
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Last modified: 03/11/2003