This article will guide you through a generic tune up on most any car or light duty gasoline-powered vehicle built within the last 20 years or so. We will presume that you are tuning up your engine because it has reached the mileage or time point to do so, and that you are NOT performing a tune up to cure an engine performance defect. We make this distinction because not all running/performance issues will be solved via a simple tune up.
You are working on an automobile engine, so please follow these simple precautions which will go a long way toward ensuring your safety and comfort:
- Wear comfortable clothing that covers your arms and legs and is not too loose-fitting.
- Remove all jewelry including watches and rings.
- Tie back long hair.
- Wear closed-toe shoes, preferably work boots.
- Eye protection is critical when working with moving parts, with power tools, or when underneath an automobile.
- Have a supply of latex or nitrile disposable gloves to protect your hands.
- Good workshop habits include having some hand cleaner, clean rags or paper towels, a flashlight and a fire extinguisher nearby.
For most vehicles built since the early 1990s, an “engine tune up” will include:
- Replacement of the air filter.
- Replacement of the fuel filter.
- Replacement of all spark plugs.
- Replacement of spark plug wires (if equipped).
- Replacement of distributor cap and rotor (if equipped).
- Checking and setting distributor timing (if equipped).
- Overall check of underhood fluids and connections.
a. PARTS NEEDED: NEW FUEL FILTER
b. TOOLS & EQUIPMENT NEEDED: OPEN ENDED WRENCHES, SCREWDRIVERS, FUEL LINE DISCONNECT TOOLS, DRAIN PAN, RAGS
Note that Steps 3 (spark plugs), 4 (plug wires) and 5 (distributor cap) all involve removal of the spark plug wires. If you’re a novice at this, do these steps one at a time. If you’re confident, read through all these steps with the understanding that you can perform these replacements simultaneously.
Break the plug loose, and completely unthread it. As you lift the socket, the plug should stay inside. Take a quick look at the spark plug electrode (tip). It should be brownish in color. Very wet or oily spark plugs, or plugs which appear to be missing their tips, are indications of other problems which a fresh set of plugs will not fix!
Check the gap on the new plugs and adjust to spec, using an appropriate plug gapping tool. (Some spark plug manufacturers claim that their plugs are “pre-gapped” and do not need checking/setting.) Begin the installation of the new plugs by hand, which helps avoid stripping threads. Finish the installation with a torque wrench set to the vehicle manufacturer’s specs. Reinstall the plug wire or coil, and move to the next cylinder.
a. PARTS NEEDED: NEW SPARK PLUGS, ONE PER CYLINDER
b. TOOLS & EQUIPMENT NEEDED: SPARK PLUG SOCKET, RATCHET WRENCH, EXTENSION BAR, SPARK PLUG GAPPING TOOL, TORQUE WRENCH
a. PARTS NEEDED: NEW SPARK PLUG WIRE SET
b. TOOLS & EQUIPMENT NEEDED: SPARK PLUG WIRE PLIERS, MASKING TAPE, MARKING PEN
6. Distributor timing is the last step in our basic tune up outline. You’ve replaced the air filter, fuel filter, spark plugs, plug wires, distributor cap, and distributor rotor. Note that all these operations must be done with the engine OFF; indeed, there are some technicians who will go so far as to disconnect the battery to avoid any potential short circuit (not necessary, but could be considered a best practice). If your vehicle has a distributor, then its “timing” is adjustable. This refers to how the distributor is geared or “timed” in relation to the engine crankshaft. If adjustable, a clamp at the bottom of the distributor can be loosened, and the distributor rotated.
7. While the hood is open, your hands are dirty, and you have some tools and supplies at your disposal, it is a best practice to perform some basic checks. Do the following:
- Check engine oil level (car on level ground, engine off for at least 5 min.) and top off.
- Top up windshield washer fluid (use 100% washer solvent in the winter).
- Check power steering, brake, and transmission fluid levels. Top up, however, be prepared for further checks if any of these levels are significantly low.
- Perform a visual check of the battery terminals: they should be clean and tight.
- Perform a visual check of the underhood fuse box. All fuses should be present, without any signs of stains, oils, or scorch marks.
- Perform a visual check of the engine drive belt or serpentine belt. There should be no signs of fraying or cracking. Press your thumb against the belt to make sure there is adequate tension. In general, you should be able to deflect the belt about ½”.
Of course, if anything under the hood appears abnormal, you will need to continue your diagnosis, or take the vehicle to a professional for further assistance. To complete your tune up, take the vehicle for a ride. Allow the engine to fully warm up. Listen carefully for any abnormal sounds. Overall performance should at least be equal to what you had previously; ideally, you will notice some increased performance as well as better fuel economy. Finally, take pride in a job well done!