Fall Tune-Up

Words and Photos By: Mark Yanochko

As we approach winter after a summer of hard, fun driving, it might be time to check out how your car, minivan or SUV is running. While the traditional tune-up (ignition points/condenser/spark plugs), that was necessary at least once a year, disappeared with the arrival of electronic ignition, there are several tasks that you can perform to freshen the performance of a vehicle’s engine—and improve fuel economy. At this time of the year, we’ll call it the fall tune-up.

Not every one of the tasks listed needs to be done every year. If, however, you just put gas in your car and change the oil, you might want to take a closer look at this list. Listed below are the four basic tasks for the fall tune-up:

1. Change the air cleaner element
2. Clean the throttle body
3. Replace the spark plugs and wires (if equipped)
4. Clean the fuel injectors

CHANGE THE AIR CLEANER ELEMENT

The first task to perform for the fall tune-up is changing the air filter. An engine needs to breathe easy in order to perform at maximum efficiency. This is accomplished with a clean air filter element. The filter element, A, shown in Figure 1, has a considerable build up of dirt. This filter element has exceeded its service life. Notice the difference between the dirty element and the clean one, B.

CLEANING THE THROTTLE BODY

Next on the list is the throttle body. Over time, dirt will start to build up in the throttle body, which can cause rough idle and other driveability issues. If you look into the throat of the throttle body, C, you’ll see a ring of dirt, D, around the throttle blade, E (Figure 2). This area of dirt extends through to the back side of the housing. The easiest way to clean the throttle body is to remove it from the engine and do the job on your workbench (removal of a throttle body is pretty straightforward). The cleaning agent that you should use is Mopar® Throttle Body Cleaner, part no. 04897156AA.

With the housing on the workbench, turn it over and spray the back side of the throttle blade, F, and the housing with the cleaner as shown in Figure 3. A rag should be used to clean the surfaces of the throttle body blade and housing. Spray the inlet side of the housing, too, and clean it in the same manner. Open the throttle blade, G, and, using a small brush, H, clean the ring of dirt (Figure 4). After you’ve finished cleaning the housing, spray it with the cleaner to remove 
all traces of dirt. Then, dry the housing with a clean rag. Use compressed air, if available.

REPLACE THE SPARK PLUGS

Ignition systems have benefited greatly from the use of electronics. The net result is a hotter, cleaner spark to ignite the air/fuel mixture. Because lead is no longer used in gasoline, plugs remain cleaner for a longer period of time, too. Spark plugs last longer, but the increased heat in the engine compartment can take a toll on the ignition wires.

There are two different ignition systems being used on Chrysler Group vehicles. The first system is the coil, J, wire, K, and spark plug, L (hidden by the boot), shown in Figure 5. The other is the coil-on-plug, M, which does not use a traditional spark plug wire (Figure 6).

A clean burning plug will have a light brown color. Deposits of oil indicate a serious oil leak problem, perhaps past the piston rings. Heavy carbon deposits can indicate a fuel mixture problem. In Figure 7, such a used plug, N, has seen extensive service compared to a new one, P. Because this plug was not replaced within the normal maintenance interval, the center electrode is nearly burned away. The excessive gap can cause misfire problems.

Use a feeler gauge to accurately set the electrode gap on the new plug if it has a flat tip electrode. If the plug has a platinum electrode, use a tapered gauge.

When replacing plug wires, be sure to route the wires correctly and secure the wires in the appropriate retainers. Failure to do so can cause radio ignition noise or short circuit the wires to ground.

CLEAN THE FUEL INJECTORS

The last task for the fall tune-up is cleaning the fuel injectors. Dirty fuel injectors can also be a source of driveability problems and poor fuel economy. Dirt accumulates near the pintle valve, which can inhibit the fuel spray and affect the spray pattern of the fuel.

Mopar Fuel Injector Cleaner, part no. 04318007 can be used to clean these dirty injectors. Pour the cleaner, Q, into the gas tank as shown in Figure 8. The fuel injectors are cleaned while you drive.