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Ford introduced the Mustang in 1964 and it has since remained one of the best-selling sports cars on the market. The Mustang entered its eighth generation in 1999 and remained basically the same until Ford rolled out the ninth generation in 2005. The 2000 Mustang came in convertible and coupe trims with either a 3.8-liter, V-6 engine or a 4.6-liter, V-8 engine. The bolt-torque specs for the intake manifold were the same for coupes and convertibles with the V-6 engine, regardless of the transmission.

Torque Basics

In general terms, torque is the amount of force applied to twist or turn an object. It is often given in foot-pounds, with the measurement equaling the pounds of force applied at the end of a lever of a given length. For instance, 100 foot-pounds equals 100 pounds of pressure applied to a foot-long wrench. Larry Carley, the Technical Editor for the website "Underhood Service," recommends that bolts should be cleaned and lightly lubricated with clean motor oil before tightening them because any debris on the bolts or in the bolt fixtures could cause additional friction and thus increase the amount of torque necessary for an ideal fitting. It is extremely difficult to gauge torque by touch. Most mechanics use torque wrenches to ensure that the proper amount of torque is applied, as over-tightening a bolt can be just as bad as not tightening a bolt enough and cause the bolt to snap.

Torque Specs for the Upper Intake Manifold

All bolts in the upper intake manifold of the 2000 V-6 Ford Mustang engine must be tightened in three steps. First, tighten each bolt with 53 inch-pounds of torque. Next, tighten each bolt to 71 inch-pounds of torque. Finally, rotate each bolt an additional 90 degrees.

Torque Specs for the Lower Intake Manifold

The bolts in the lower intake manifold of the 2000 V-6 Ford Mustang engine must be tightened in two steps. First, tighten each bolt to 44 inch-pounds of torque. Second, tighten each bolt to 89 inch-pounds of torque. In addition, "The Motor Repair Manual" for 2000 recommends applying beads of silicon gasket sealant to the gasket of the lower intake manifold.

On an automobile, the intake manifold is mounted to the engine block above the cylinder or port openings. Older intake manifolds are made of cast iron, but most new ones are plastic or die-cast aluminum.

Purpose on Older Engines

On older vehicles the intake manifold delivers the right mixture of air and fuel evenly to each of the cylinders. Heat vaporizes this mixture, providing optimum delivery in mist form.

Location on Older Engines

On an older engine, both sides are flanked by the valve covers, and its top is partially obstructed from view by the carburetor and air cleaner mounted above.

Purpose on Newer Engines

New engines have replaced the carburetor with a tuned-port injection system. Because these deliver the fuel directly to the ports, air and fuel no longer need to be mixed in the intake manifold. On these engines the purpose of the intake manifold is to deliver the proper amount of air to each of the ports, where it will be mixed with the fuel.

Location on Newer Engines

On newer engines, the intake manifold is connected to the ports on the engine. Hoses attached to the intake manifold are to operate vacuum systems such as brakes, cruise control and the air-conditioning. (See References 1)

Engines transform air/fuel mixtures into combustion, creating horsepower. Engine combustion creates exhaust gasses that must be expelled from the combustion chamber in order to keep the air/fuel mixture clean. Intake systems improve combustion, while exhaust systems relieve an engine of waste gasses.

Air Intake Components & Function

Combustion is a mixture of fuel and air. While engines inject fuel drawn from a fuel tank, the air is pulled from outside through the intake system. Air is drawn through an intake tube and into a filter-protected air box. From there the air is driven into the combustion chamber.

Exhaust System Components & Function

Exhaust gasses exit the combustion chamber through an exhaust manifold that is secured to the engines cylinder heads. Exhaust then travels through a front pipe and into a catalytic converter, which filters harmful chemicals such as carbon monoxide. The cleaner exhaust finally travels through the muffler and out the tailpipe.

Performance Benefits

Upgrading intake and the exhaust system benefits engine-based performance. Aftermarket exhaust systems are designed to optimize exhaust flow and velocity while reducing back-pressure. This is accomplished through a change in piping diameter. An upgraded intake pulls increased air more directly through the filter. Both upgrades improve horsepower and fuel efficiency while increasing engine sound.

Hot air is not as dense as cold air and therefore requires less fuel to balance an engines air/fuel ratio. The intake air temperature sensor keeps track of the temperature of the air going into an engine. This vital info is then used by an engines computer (PCM), which allows it to keep air/fuel mixture in balance.

Process

An intake air temperature sensor is normally positioned in the intake manifold so that its tip can meet the air going into the engine. The PCM sends around 5 volts to the sensor and waits for a voltage signal response. Air intake sensors have certain resistance reactions to different air temperatures, and this resistance will determine the voltage reading thats sent back to the PCM.

Problems

Faulty air intake temperature sensors can provide incorrect readings to a vehicles PCM. This can cause the PCM to mistake warm air for cold air, which will result in incorrect air/fuel mixture. This in turn leads to idling problems, which can cause a car to shut off, especially in cold weather. Other driving problems include trouble accelerating as well as engine surging.

Reasons

There are several reasons why an air intake temperature sensor can fail, such as bad electrical connections, which lead to incorrect sensor output. Oil from the intake manifold can also coat and contaminate the sensor, limiting its ability to properly monitor air temperature.

Every engine component plays a key role in your cars function, and the intake system is no exception. If the intake backfires, this is an issue that must be addressed immediately. However, diagnosing and fixing this problem requires some knowledge of the system. Understanding the intake system and the causes of backfiring will help you confirm or rule out this issue.

Intake Manifold

It is necessary to understand the intake system in order to see how backfiring occurs. The intake valve is a component of the intake manifold. The manifold is located on the top of V6 and V8 engines. For inline four- or six-cylinder engines, the intake manifold is installed on the side. The manifolds job is to provide a mixture of air and fuel to the engines cylinders. To do this, the intake valve opens to draw gas and air into the engine. After opening, the valve closes to keep this air and fuel combination trapped inside.

Cause of Backfiring

Backfiring is a small explosion. Although there are many problems that can cause the intake system to backfire, the overall effect is the same. Since the intake valve needs to provide the engine with a proper balance of fuel and air, a backfire occurs when that balance fails. In this case, having less fuel than air in the mixture will cause the small explosion. Luckily, this does not result in serious damage.

Main Cause

Engines are full of components, many of which can malfunction to trigger a backfire. The most common reason for this is a faulty fuel system. The fuel system consists of three components: the vacuum, the airflow sensor and the oxygen sensor. All of these parts are responsible for maintaining the air-to-fuel balance in your engine. If any of the parts are damaged or defective, backfires can occur.

Other Causes

A leak in the air injection system can also cause the intake to backfire, since this affects the amount of air taken in. Another possible reason is a malfunctioning fuel pump or obstructed air filter. The intake system must be timed correctly so that it can feed fuel and air to the spark plugs at a proper rate. If this timing is off, it can be another cause for backfiring.