Engine Maintenance and Questions Guide
Just to let you know…
If your check engine light comes on, there is no need to panic right away!
When the ignition switch is initially turned on and the engine is not running, the malfunction indicator lamp lights for a bulb check. While the engine is running, the MIL will light only if there is an emissions-related concern.
The onboard diagnostic (OBD) generation II system continuosly monitors all engine and transmission sensors and actuators looking for electrical faults, as well as values that do not logically fit with other powertrain data. When certain operating conditions are met and a comprehensive monitor detects a failure that will result in emissions exceeding a predetermined level, the computer stores a diagnostic trouble code and illuminates the MIL.
The onboard diagnostic II system also actively tests some systems for proper operation while the vehicle is being driven. Fuel control and engine misfire are checked continuosly, catalyst efficiency, exhaust gas recirculation operation, evaporative system integrity, oxygen sensor response and oxygen sensor heaters are tested once per trip when prerequisite operating conditions are met. The computer will illuminate the MIL if during these prerequisite operating conditions the system detects a failure that will result in emissions exceeding a predetermined level.
Whenever an engine misfire severe enough to damage the catalytic converter is detected, the MIL will blink on and off.
Once lit, the MIL will remain on until the vehicle has completed three consecutive good trips. The MIL is also turned off when stored diagnostic codes are cleared. However, the MIL will only remain off if the fault is successfully repaired.
One of the most common reasons your check engine light comes on is for an evaporative emissions leak.
Evaporative emissions: These are produced from the evaporation of fuel, and are a large contributor to urban smog, since these heavier molecules stay closer to ground level. Fuel tends to evaporate in these ways:
Gas tank venting: The heating of the vehicle as the temperature rises from night to day, mean that gasoline in the tank evaporates, increasing the pressure inside the tank above atmospheric pressure. This pressure must be relieved and before emissions control it was simply vented into the atmosphere.
In 1996 and newer vehicles, the federal government required manufacturers to place a leak detection pump on vehicles. This pump services the purpose of putting a vacuum on the system to detect leaks. Because of this system, loose gas caps and filling the vehicle with gas while the engine is running can cause the light to come on.
What is an EGR valve?
Exhaust gas recirculation (EGR) is NOx (nitrogen oxide and nitrogen dioxide) reduction technique used in most gasoline and diesel engines. In a typical automotive engine, 5 to 15 percent of the exhaust gas is routed back to the intake as EGR (thus comprising 5 to 15 percent of the mixture entering the cylinders). The maximum quantity is limited by the requirement of the mixure to sustain a contiguous flame front during the combustion event; excessive EGR in an engine can cause misfires and partial burns. Although EGR does measurably slow combustion, this can largely be compensated for by advancing spark timing. Contrary to popular belief, EGR actually increases the efficiency of gasoline engines via several mechanisms. Recirculation is usually achieved by piping a route from the exhaust manifold to the inlet manifold, which is called external EGR. A control valve (EGR valve) within the circuit regulates and times the gas flow. Some engine designs perform EGR by trapping exhaust gas within the cylinder by not fully expelling it during the exhaust stroke, which is called internal EGR.
What is an oxygen sensor?
An automotive oxygen sensor, also known as an O2 sensor, is a small sensor inserted into the exhaust system of a petrol engine to measure the concentration of oxygen remaining in the exhaust gas to allow an electronic control unit to control the efficiency of the combustion process in the engine. In most modern automobiles, these sensors are attached to the engine’s exhaust manifold to determine whether the mixture of air and gasoline going into the engine is rich (too much fuel) or lean (too little fuel).
This information is sent to the engine management ECU computer, which adjusts the mixture to give the engine the best possible fuel economy and lowest possible exhaust emissions. Failure of these sensors, either through normal aging or the use of leaded fuels, can lead to damage of an automobile’s catalytic converter and expensive repairs.
The downside of oxygen sensors is that they defeat many fuel saving technologies. If the engine burns too lean from any modifications, the sensor detects that the exhaust is too lean. It then sends the signal to cause the injectors to enrich the mixture by supplying more fuel. This causes the air-fuel mixture to stay within the stoichiometric ratio of 14.7:1 on a typical vehicle.
There are many ways to overcome this efficiency defeating mechanism. Several companies manufacture a device that can be inserted inline with the sensor and tricks the voltage signals into thinking it is within normal parameters. Therefore, any modification for cleaner burning will not be defeated by the oxygen sensor.
This self-defeating mechanism is why some legitimate fuel saving technologies actually cause a loss in gas mileage.
What can I do about?...
My gas mileage is not good, is there anything that can help?
You guys recommended a fuel system cleaning. What is that and what does it do?
In a fuel injection engine, the throttle body is the part of the air intake system that controls the amount of air flowing into the engine in response to driver input. While the accelerator is often called a gas pedal, it would be more accurate to describe it as an air pedal. The throttle body is usually located between the air filter box and the intake manifold and usually attached to, or near, the mass airflow sensor. The largest piece inside the throttle body is the throttle plate, which is a butterfly valve that regulates the airflow.
Where do the deposits come from? Mostly from the fuel itself. Gasoline is a mixture of many different hydrocarbons, including oilfins which are heavy, waxy compounds. The heavier the hydrocarbon, the more energy it yields when it burns. Oilfins give gasoline more bang for the buck. When the engine is shut off, the fuel residue in the injector nozzles evaporates leaving the oilfins behind. Because the engine is off, there is no cooling airflow through the ports and no fuel flow through the injectors, so heat bakes the oilfins to form hard varnish deposits. Over time, these deposits can build up and clog the nozzle.
Since your car was new, dirt, varnishes and carbon deposits have been forming in your vehicle’s fuel system, on the intake valves and in the combustion areas. These contaminants can rob your vehicle of performance, fuel economy, increase harmful emissions and could lead to costly engine repairs if left untreated.
When the engine is contaminated with carbon deposits, gum and varnish, your car’s ability to drive smoothly and cleanly is compromised. Traditional tune-ups can’t fix these problems. That is the reason we recommend a fuel system cleaning.
There are a lot of benefits from doing this service:
In most cases customers have seen up to a 27% increase in gas mileage
Reductions in knocking internally within the engine
Reductions in hesitation.
Reductions in rough idle
Decreases in harmful emissions
Increase in power
Increase in performance
Maintains the emission warranty
Helps promote a quick-starting, smooth running engine
Prevents costly throttle body and fuel injector replacement
Can restore up to 45% lost horsepower
Did You Know?
Most manufacturers require timing belts to be replaced as early as 60,000 miles!
What is a timing belt?
The job of a timing belt is to turn the camshaft at exactly ½ the speed of the crankshaft while maintaining a precise alignment. This means that the crankshaft will make two revolutions for every revolution of the camshaft. Engines will have at least one camshaft, or as many as four. The camshaft causes the intake and exhaust valve to open and close in time with the pistons which move up and down in the cylinders. The valves must open and close at exactly the right time in relationship to the piston movement in order for the engine to run properly.
Why should I do this service?
The biggest issue with failed timing belts on vehicles is the catastrophic damage that can occur. When the engine is running with an intact belt, the valves move up and down in time with the pistons and the two objects miss each other hundreds of times per second. When a timing belt fails on a vehicle, the cams quickly spin to a stop and the pistons keep going. If any of the valves stop in the down position the piston will come up and deliver it a terrible whack.
At minimum, this means bent valves and at its worst can knock a hole in the piston. Or, if the belt breaks at high revs, the shattered bits of valve will bounce around in the combustion chamber, beating the cylinder head to death. For this reason, if you break one you are most likely in for a head job at minimum and possibly lower-end repairs if the damage is substantial. Why play roulette?
Which engine schedule should I follow and why?
In order to maintain your vehicle in its best condition, it is critical that you adhere to the appropriate maintenance schedule. Most manufacturers publish two required maintenance schedules that should be applied based on whether your vehicle is driven under “severe” or regular conditions. You should choose the severe maintenance if you drive your vehicle under any of the following conditions:
Driving on dusty, rough , muddy or salt spread roads
Towing, Police, Taxi or commercial operation
Repeated short-trip operation
Extensive idling and or low speed operation
Extensive use of brakes while driving
Driving in sandy areas
More than 50% operation in city traffic during hot weather above 90 degrees
Repeatedly driving short distance of less than 5 miles in normal temperature or less than 10 miles in freezing temperature
Driving conditions around the country result in the majority of drivers needed to follow the Severe Maintenance Schedule.
Why should I do my required maintenance?
The main reason is for protecting and prolonging the life of your investment. The life of your investment can be severely diminished if the recommended maintenance is not performed. This also causes severe depreciation on your trade-in.
Secondly, All the manufacturers we service along with the service contracts we offer require many maintenance items to be performed. Failure to perform this can cause restrictions or complete voiding of warranties. These statements are listed in your owners manual/maintenance log.
