How to do a tune up

Even though you may not know how to tune up a car, it’s really not that hard. The basic idea of a tune up is that you’re not actually repairing the car, rather you’re maintaining it. There are several items under the hood that need occasional replacement or checking from time to time. A tune up usually involves most of these and will either keep your car running in tip top form or help it get back to tip top form. The classic tune up involves the following:

  • change the spark plugs
  • change the spark plug wires
  • change the rotor within the distributor
  • change the distributor cap
  • set the timing
  • change the air filter
  • change the PCV valve

There are other items that you might want to check while under the hood, but since they’re not part of the tune up process per se, we’ll omit them here.

Tools you’ll need for the job:

  • Metric socket set (including a 19mm spark plug socket)
  • Screwdrivers (may only need phillips or flat blade, but you might as well have both at hand)
  • Timing light
  • Spark plug gap guage
  • Torque wrench (optional, but a good idea)

Parts you’ll need from the parts store:

  • Spark plugs (stay away from “Champion” brand! “NGK” brand plugs are pretty good)
  • Spark plug wires (7mm or thicker preferably - Magnacor wires are pricey but VERY good)
  • PCV valve (usually just a couple of bucks)
  • Air filter (usually just a couple of bucks unless you want a “performance” air filter like K&N)
  • Distributor cap (usually about $30US)
  • Rotor (usually just a couple of bucks)

The Tune Up Procedure

The Plugs

Although you’re not likely to get confused it is possible, so it might be wise to label or otherwise mark the spark plug wires so you know which is which when you need to reattach/replace them. Assuming that you have done so, remove the plug wires from the spark plugs by gently pulling from their rubber boots not the actual wires themselves. You may want to use a plug wire puller for the job. This is a simple device that essentially is a screwdriver handle and shaft with a curved, forked end that fits under the plug wire boot and allows you to exert even pressure at the right point. There are other versions too. The tool is handy but not necessary.

With the plugs exposed, use compressed air or a brush to clean out around them. This will avoid dirt and debris falling into the cylinders when the plugs are out. After cleaning the dirt away use a 19mm spark plug socket to remove each plug. Look at them to see if they have any unusual wear. All plugs get dirty and somewhat scorched, but you want to look for conditions beyond the ordinary. Look for excessive blackening (which indicates fouling caused by a too rich fuel:air mixture), grayish looking scorching, signs of excessive heat, cracking, etc. Noticing such things can help track down certain problems. The new spark plugs should be “pre-gapped”, that is, the gap at tip of the plug where the spark occurs is usually preset to a specific width for optimum results. Generally you shouldn’t have to gap new plugs, but it is a good idea to guage the gap on each to be sure you’re not “installing a problem”. Refer to the Specs page (coming) for proper gap. Install the plugs and tighten to the proper torque settings if you have a torque wrench, if not a good rule of thumb is tighten them until they stop under “normal” force, and then another 1/8th turn.

The wires

Replacing spark plug wires is one of the easiest things to do under the hood. With the stock wires disconnected from the plugs, it should be fairly straightforward to swap in your new wires. Usually each wire is a different length and should be pretty easy to match up. There is also a wire leading from the center of the cap to the ignition coil (a cylindrical shaped item near the strut tower). That’s why there’s an odd number of wires… it includes a wire for the coil. Simply unplug each wire from the distributor cap, replace it with a corresponding new one, and move on to the next wire. Which brings us to the next section…

Replacing the distributor cap and rotor

When you’re replacing the spark plug wires you might want to just go ahead and reconnect them to their corresponding locations on the new distributor cap. The sockets on the cap are usually numbered and correspond to a like wire. If you simply connect the new wires to the right sockets on the new cap, you should then just be able to replace the cap and sort of save yourself some time and effort.

To remove the cap simply loosen the two 10mm bolts holding it in place (look down beside the cap). You’ll want to loosen them until they seem to want to fall out, but they should stay in pretty much on their own as long as you don’t get too careless in handling the loose cap. Carefully pull the cap off and remove the two bolts completely - you’re going to need them to put the new cap back in. Again, if you’re replacing the wires, this is a good time to hook them up to the new cap as well.

While the cap is out, replace the rotor with the new one you picked up at the parts store. The rotor is the odd shaped plastic and metal thing inside the distributor. To remove it, there is a small screw on one side that goes into a shaft that the rotor sits on. If you can’t get to the little screw, put the key in the ignition and crank the car very lightly once. This is sometimes called bumping the starter. This will make the rotor turn a bit. Do this until you can adequately reach the little screw. (Now, sometimes the screw is a regular screw and sometimes it has no slots for a screwdriver, having instead a “grippy” knurled head that can be tightened and loosened by hand. I don’t know if that’s good or bad.) Remove the screw and replace the rotor.

Replace the cap. Tighten the two 10mm bolts back in place. But is the cap located in the right position? To determine that you’ll need to set the timing. This is where that timing gun comes in handy. To set the timing you should refer to the “How to” called, “Setting the timing“.

Changing the air filter

Changing the air filter is pretty simple. The air filter is located in the metal box against the inside of the fender, with the big plastic tube running to the engine. The tube is the air intake tube and it leads to the throttle body, located under the “Flat 6″ or “H-6″ labled metal plate (the throttle body cover). To change the filter, you’ll need to unclamp the top half of the filter housing (the metal box thing) and carefully lift it upwards enough to slide the old filter out and the new filter in its place. Be careful not to force the plastic air intake pipe too far as it could crack. Cracks can be fixed but it’s best to just avoid them. You may want to just remove the intake pipe from the throttle body and then reattach it after you’ve put the new air filter in.

Changing the PCV valve

Last, but not least, you’ll want to change the Positive Crankcase Ventilation, or PCV, valve. The PCV valve is located under the “Flat 6″ or “H-6″ plate that covers the throttle body and air intake manifold. A hose leads from the big plastic air intake tube to a metal pipe with three branches. One of these has a hose that leads to the PCV valve. trace the route of the hose that leads up and under the throttle body cover (the “Flat 6″/”H-6″ plate). Remove this hose, taking note of its position so you’ll know how to replace it a few minutes later. Removing the hose exposes the PCV valve. Use a socket wrench to remove it and to replace it with the new PCV valve. The spark plug socket you used before should work just fine in most cases. Once the PCV valve has been replaced, reconnect the hose(s) and any other diconnected items.

You just tuned your car up and saved a fair amount of money as well!

One response to “How to do a tune up”

  1. Subdudext6 Says:

    Always, always remember to clean out the Idle Air Control valve (IAC) when doing a tune up. You’ve got the intake tube off anyway to get at the PCV valve.

    The IAC is located on the same side as the PCV valve. Disconnect the top wire that goes to the IAC, remove the 10mm screw, and remove the valve.

    Run Air Intake Cleaner (NOT Choke cleaner, NOT brake cleaner) through it. You will see a lot of crud coming out, especially on a higher mileage car. Best to clean it out every 2-3 oil changes. When dirty, it can cause the car to idle rough, and when you clean it out it helps make the IAC valve last longer also, because the little electric motor in it can be fouled up by crud. It’s not a cheap part.

    Anyway, just thought I would add that. It’s on my list every time I tune up.

    Ed: GREAT advice!

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