A list of various performance, maintenance, and gas mileage tips that would not otherwise get their own article in the Ford Escort & ZX2 section.

• Oxygen Sensor: The primary (upstream) oxygen sensor controls the mixture at part throttle. Oxygen sensors lose their ability to adjust themselves properly after a while, or usually 60-80k miles. New ones will generally cost $ 50-100. The second o2 sensor does not have to be replaced because it jus tmonitors the efficiency of the catalytic converter. If the exhaust is upgraded however, and the catalytic converter is eliminated, an o2 sensor simulator can be built to avoid setting off any engine codes.
• Fuel: All 1998 and later Escorts and Focuses have a knock sensor, the computer retards ignition timing whenever it detects any spark knock or detonation, long before it can be heard. This has a very negative effect on both power and fuel economy. However unless an engine is set up to use premium fuel (i.e. high compression head, advanced timing, etc) in most cases running premium fuel will not help economy. The only thing "Premium" means is higher a octane rating which is the fuel's resistance to detonation or knock in the engine.
• Fuel Injectors: Your fuel injectors must be clean to atomize the fuel and provide the correct air/fuel ratio. You can have them cleaned at a garage where they hook up a can of cleaner on the fuel rail and run the engine directly off of it. The best way is to use an in tank cleaner. The best I have used it Chevron Techron available at most auto parts stores for about $10 for the larger bottle. It's the only one that I have used that actually made a difference in the way the engine runs. I usually run it a bit stronger than what the manufacturer calls for and fill up the tank. Then run the tank down to about 1/8 or so on the cleaner. If you keep filling it up, you'll just dilute the cleaner. I like to run this about every other oil change. There are many cheap cleaners on the market that seem to do nothing.
• Throttle Body: Check to make sure your throttle blade is opening all the way This is overlooked by a lot of people. With the engine off, remove the air induction hose from the throttle body and then have someone push the accelerator pedal to the floor and hold it there. Look at the throttle blade in the throttle body. It should be rotated to 90 degrees from the direction of the airflow. If not, the throttle cable or manual stop on the throttle body itself may need readjustment. If it doesn't open fully, then you aren't getting full throttle power. Take whatever steps necessary to correct this problem if it exists.
• Spark plug wires: Many cheap and factory wire sets are carbon core. They have quite a bit of internal resistance and do tend to break down after a while. Wires can easily be checked with an ohm meter measuring the resistance. The resistance will vary by the length. Just figure ohms per inch. The best wires are the spiral core. They have a spirally wound connector that reduces the electrical resistance without setting up any electromagnetic signals which can effect the computer and radio. (Solid wire core spark plug wires cannot be used in modern vehicles with electronics) Spiral core wires last much longer and only have about 14% of the resistance of carbon core wires. This allows more energy from the coil to reach the plugs providing a hotter spark. With these wires, you can open the plug gaps a little more for a better burn. This combination smoothes the engine out, especially at idle, and improves part throttle torque and fuel economy.
• Spark plugs: There is much to be gained by the sparkplugs. Years ago we experimented with side-gapped plugs. They worked better than anything else by allowing a free path for the spark into the combustion chamber. Even widenig the gaps on regular plugs helps as long as there is enough power in the ignition system to fire them. Our dual gap plugs are gapped wider than stock for a larger spark. They also are of a side-gap design and much less spark shrouding. More electrodes don't mean more sparks. The plug will fire only once each cycle and then usually from the coolestm sharpest surface. More grounding electrodes just add to the shrouding of the spark but will make the plugs last longer since the wear is distributed between more electrodes.
• Engine oil: Better lubricants are necessary in any performance vehicle. Synthetic lubricants are far better than most mineral based lubes. They provide better cold weather flow qualities, much less friction, and don't break down from excessive engine heat nearly as much. Thinner oils reduce pumping losses and reduce drag in the engine. Don't buy into any of the myths about using thicker oil. For economy, a 5w20 synthetic will work well. For engines run hard or that have a lot of miles and wear, you may need something a little heavier like a 5w40 grade. Always use a premium oil filter. Ford filters are very high quality and that's all we ever use. The recommended change interval for synthetic oil is about 5,000. Doing this, I've never seen any serious wear or sludge in engines that had well over 200,000 miles on them. I have also used an additive called ProBlend in the oil that seems to cut friction and help the fuel economy. It definitely reduced the oil temperature (measured with a gauge).
• Transmission fluid: The transmission oil should also be changed over to synthetics. This aids friction loss and shift quality in manual shift cars and automatics alike. Automatic transaxles need to be flushed to remove all the old fluid from the entire system. Only draining it, even with the pan removed, only removes about half. The pan should be removed anyway before flushing to clean it and the filter/screen out. There are 2 magnets in the bottom that trap metal particles. These will be heavily coated in higher mileage cars where they haven't been cleaned.
• Tire inflation: Your tires need to be properly inflated. This should be checked about once a month. Any major temperature change will affect the tire pressure. Tires should be checked cold and then verified when hot after a long highway drive. Make sure the maximum pressure doesn't exceed the tire manufacturer's recommendations printed on the sidewall. A little research into low rolling resistance tires may be benificial. Also, wider tires usually are harder to roll/push so will slow the car to some degree.
• Alignment: For maximum fuel economy and acceleration, the tires should be aligned to be vertical and to be pointing straight ahead when the vehicle is normally loaded. Any changes in weight changes the alignment. We like to have them aligned in the condition they will most commonly be used. One or two passengers and possibly a full tank of fuel. Have your alignment specialists align the car loaded as such (if possible) and adjust in the window of the factory specifications as close to being zero toe and zero camber. This isn't the best setting for all-out handling but in normal driving, will never be noticed. Everything is a compromise.

Also see

• Ford Escort & ZX2 section for the entire index of all Ford Escort and ZX2 related articles.