With modern 4x4s the standard tune-up no longer exists. Sure, you can throw in new spark plugs if you can get to them, and maybe replace the cap and rotor, if the rig has a distributor. But by and large the standard tune and drive has been replaced with fault codes and sensor replacement, which just isn't the same as timing an engine by ear.
What usually tips the driver off to an engine problem is the hideous "check engine" light on the dashboard, or worse yet, the engine icon on the newer rigs. While this indicator could mean that something as simple as the gas cap is loose, the only way to figure it out and fix the rig is to read the codes stored in the vehicle's computer. This used to mean taking the vehicle to the dealer, making an appointment, and letting them hook your baby up to a monstrous machine with various umbilical cords, and then receive a hefty bill for this diagnostic treatment. Not only that, this process only told you what's wrong--fixing it was another appointment and another big bill. Not that we have anything against dealerships or spending money, but there is another way. We picked up an Actron Super AutoScanner, which is very similar to what your regular garage mechanic uses nowadays. Various other brands and models are available, but they all work the same basic way, by reading the codes stored in your vehicle's computer.
However, the Super AutoScanner does more than just read the code; it can also clear the codes and perform other diagnostic tests. By simply plugging the unit into the vehicle's diagnostic port, a few simple keystrokes can confirm that your O2 sensor is dead, or if some other problem has triggered the check engine light. Not only that, the unit can reset the light and allow for many more happy motoring miles.
1.) The Actron Super AutoScanner is capable of reading and clearing codes from '84-'95 OBD I-equipped vehicles, and '96-and-newer rigs with OBD II systems. These On Board Diagnostic systems let you know what's going on with your rig, if you have an easy-to-read tool like this one. | 
2.) Most vehicles have a diagnostic port under the dash or under the hood, and many adapter cables are available for the oddball models. The Actron unit is extremely sophisticated, but so user-friendly that even we could figure it out in a few minutes. |
3.) Our initial problem with our Ford Explorer was a "check engine" light coming on, and not having the wherewithal to deal with it. We knew it could mean nothing important, but the glowing amber usually indicates a faulty component. The OBD systems on today's vehicles monitor many emissions, ignition, and fuel systems. Better mileage, more power, cleaner air, and reduced risk of damaged parts are all possible by keeping your rig in top shape, and a scanner can help do that. | 
4.) The scanner indicated that we had an intermittent fuel-injector issue, and an O2 sensor on the fritz. We decided to replace the sensor, and dump some JB fuel-injection cleaner in the tank. After we cleared the computer codes with the Actron scanner, we ran the vehicle around, the light stayed off, and the Exploder is still running. |