Vacancy in vmobile nigeria

The active gasses are pumped by chemical combination with the sputtered titanium, the inert gasses by ionization and burial in the cathode, and the light gasses by diffusion into the cathode. A typical pump consists of two flat rectangular cathodes Vacancy in vmobile nigeria a stainless steel Vacancy in vmobile nigeria between them made up of many open-ended boxes. This assembly, Vacancy in vmobile nigeria inside a narrow box attached to the vacuum system, is surrounded by a permanent magnet. The anode is operated at a potential of about seven kilovolts kV, whereas the cathodes are at ground potential. The sputter ion pump has low speeds and sometimes instability when pumping inert gases. To improve its characteristics other types of sputter ion pumps have been developed: the slotted cathode, triode, differential, and magnetron Vacancy in vmobile nigeria torr, and preferably much lower, by means of a roughing pump. Sputter ion pumps can operate in any position and do not need water or liquid nitrogen supplies. They have a long life and can provide very clean, ultrahigh vacuum, free of organic contamination and vibration. They are employed mainly for the clean-surface studies and in those applications where any organic contamination will give unsatisfactory results. If you found this data interesting or useful, please let us know. If you have a useful tract or note, send it to us for posting. Vacancy in vmobile nigeria 2001-2011 McAllister Technical Services. All rights reserved. Vacuum Technology is the term applied to all processes and physical measurement carried out Vacancy in vmobile nigeria conditions of below-normal atmospheric pressure. to remove the constituents of the atmosphere that could cause a physical or chemical reaction during the process, vacuum melting of reactive metals such as titanium to disturb an equilibrium condition that exists at normal room conditions such as the removal of occluded or dissolved gas or volatile liquid from the bulk of material, degassing of oils, freeze-drying or desorption of gas from surfaces, the cleanup of microwave tubes and linear accelerators Vacancy in vmobile nigeria manufacture to extend the distance that a particle must travel before it collides with another, thereby helping the particles in a process to move without collision between source and target, in Vacancy in vmobile nigeria coating, particle accelerators, Vacancy in vmobile nigeria picture tubes. to reduce the number of molecular impacts per second, thus reducing chances of contamination of surfaces prepared in vacuum, in clean-surface studies and preparation of pure, thin films. For any vacuum process, the limiting parameter for the maximum permissible pressure can be defined by: the number of molecules per unit volume reasons 1 and 2, the mean free path reason 3, or the time required to form a monolayer reason At room temperature and normal atmospheric pressure, one cubic foot 03 Vacancy in vmobile nigeria metre of air contains approximately 7×10 molecules moving in random directions and at speeds of around 1, 000 miles per hour 1, 600 kilometers per hour. The momentum exchange imparted to the walls is equal to a force of 7 pounds for every square inch of wall area. This atmospheric pressure can be expressed in a number of different units see Table, but until Vacancy in vmobile nigeria it was commonly expressed in terms of the weight of a column of mercury of unit cross section and 760 milimetres mm high. Thus, one standard atmosphere equals 760 mm Hg, but to avoid the anomaly of Vacancy in vmobile nigeria apparently different units, a term, torr, has been Vacancy in vmobile nigeria One Vacancy in vmobile nigeria atmosphere 760 torr 1 torr 1 mm Hg. This term was replaced in 1971 by SI unit defined as the newton per square metre N/m2, and called the Vacancy in vmobile nigeria one pascal 5×10 The first major use of vacuum technology in industry occurred about 1900 in the manufacture of electric light bulbs. Other devices requiring a vacuum for their operation followed, such as various types of electron tube. Furthermore, it was discovered that certain processes carried out in a vacuum achieved either superior results, or ends that were unattainable under normal atmospheric conditions. Such developments included the blooming of lens surfaces to increase the light transmission, the preparation of blood plasma for blood banks, and the production of reactive metals such as titanium. The advent of nuclear energy in the 1950s provided impetus for development of vacuum equipment on a Vacancy in vmobile nigeria scale. Increasing applications for vacuum processes were Vacancy in vmobile nigeria discovered, as in space simulation and microelectronics.

Job vacancies nigeria lecturing

A typical mechanical booster uses two figure-eight-shaped impellers, synchronized by external gears, rotating in opposite directions inside the stator. The gas is trapped Job vacancies nigeria lecturing between the impellers and the stator wall and transferred from the high vacuum to the fore Job vacancies nigeria lecturing side of the pump. The gears are oil-lubricated but are external to the pump, so that the impellers run dry. Clearance between the impellers and the stator wall is generally about. 002 to. 010-inch. As a consequence, back leaking of gas occurs at a rate governed by the pressure difference between input and output and the type of gas being pumped. Under normal running conditions, a pressure difference of about ten to one is obtained. The mechanical booster must be backed by another pump in series when working in its normal pressure range. The most frequently used type of forepump is the oil-sealed rotary pump. Typically, the mechanical booster is employed for pumping vacuum-melting furnaces, in an impregnation plant for electrical equipment, and in low density wind tunnels. Capacities are available up to 20, 000 cubic feet per minute, with an operating range of 10 torr, when backed by an oil-sealed rotary pump. The full speed of the pump is developed in the very wide pressure range from 10 torr. In the molecular pump, a high rotational speed rotor up to 32, 000 revolutions per minute imparts momentum to the gas molecules, moving them along the small clearance between the rotor and stator. The Job vacancies nigeria lecturing drag pump also employs this principle of operation. For ultimate base pressures it has been almost entirely displaced by the faster and simpler turbo molecular pump, in which radial slots in both rotor and stator fins actuate the pump. A number of compression stages are employed but because of its design, larger clearances can be tolerated between rotor and stator than were possible in the molecular drag pump. The molecular drag pump is sometimes built integral with a turbo molecular pump to Job vacancies nigeria lecturing the use of vert clean dry backing pumps. These hybrids are often used in semiconductor processing where oil vapor backstreaming would contaminate processes but high pumping speeds are needed. This pump is mainly Job vacancies nigeria lecturing on equipment for the study of clean surfaces and in radio frequency sputtering. Pumping speeds are available up to 190, 000 cubic feet per minute with an operating pressure range of 10 torr when refrigerated baffles are employed. The pumping speed for a vapor pump remains constant from about 10 torr to well below the ultimate pressure limitations of the pump fluid. The best fluids allow pressures of better than 10 torr. The diffusion pump is initially evacuated by an oil-sealed rotary pump to a pressure of about 1 torr or less. When the pump fluid in the boiler is heated, it generates a boiler pressure of a few torr within the jet assembly. High-velocity vapor streams emerge from the jet assembly, impinge and condense on the water or air-cooled pump walls, and return to the boiler. In normal operation part of any gas arriving at the inlet jet is entrained, compressed, and transferred to the next stage. This process is repeated until the gas is removed by the mechanical forepump. The oil-vapor booster pump works on the same principles as the diffusion pump, but it employs a higher boiler pressure. Normal operating pressure range is 1 to 10 torr. When backed by an oil-sealed rotary pump, Job vacancies nigeria lecturing pump is widely used for achieving high vacuum in thin-film evaporation units, accelerators, and in TV tube pumping. Capacities are available up to 14, 000 cubic feet per minute, with an operating pressure range of 10 torr. The full speed of the pump is developed in the pressure range from about 10 torr, although the characteristic at the lower pressure is dependent on the pump design. This pump uses a cathode material Job vacancies nigeria lecturing as titanium vaporized or sputtered by bombardment with high velocity ions.

Job vacancies in charlotte north carolina

In the optical field, antireflection coatings are deposited on lenses for cameras, telescopes, eyeglasses, and other optical devices, considerably reducing the amount of light reflected by the lenses and thus giving a brighter transmitted image. torr, a pumping system consisting of an oil-sealed rotary pump and a diffusion pump is used. The oil-sealed rotary pump sometimes referred to as forepump roughs the chamber down to a pressure of about 1 torr, after which the roughing Job vacancies in charlotte north carolina is closed. The fore valve and high-vacuum baffle valve are then opened so that the chamber is evacuated by the diffusion pump and rotary pump in series. Almost every research laboratory uses vacuum directly in its experiments or employs equipment that depends on vacuum for its operation. The lowest Job vacancies in charlotte north carolina are obtained in the research laboratories, where equipment is generally similar to, but smaller than that used by industry. torr are the electron microscope, analytical mass spectrometer, particle accelerator, and large space simulation equipment. Particle accelerators range from small van de Graaff machines to large proton synchrotrons. In space simulation, large Job vacancies in charlotte north carolina that simulate space around a complete vehicle require a vacuum of 10 torr or below. Such vessels incorporate a complete shroud at liquid nitrogen temperature and a port through which high-intensity light can be beamed to simulate the suns Job vacancies in charlotte north carolina torr, research applications include electrical insulation, thermonuclear energy conversion experiments, microwave tubes, field ion microscopes, field emission microscopes, storage rings for particle accelerators, specialized space simulator experiments, and clean-surface studies. In many experiments it is not only necessary to reach such pressures of 10 torr but to reduce the hydrocarbons in the residual gases to an absolute minimum. Even small traces of hydrocarbons can render the results unreliable. To achieve a vacuum of this order the vacuum vessel and the equipment inside must be cleared of residual gas degassed to the greatest extent possible. A common solution is to bake the whole apparatus for a number of hours at about 350 C while maintaining a vacuum in the 10 torr region. Baking at this temperature requires the use of all-metal sealing rings. To eliminate hydrocarbons, the unit is pumped down to about 10 torr using sorption pumps; and from there, sputter ion pumps and titanium sublimation pumps complete the task down to 10 Capacities are available from 1/2 to 1, 000 cubic feet per minute, operating from atmospheric pressure down to as low as 2 x 10 torr for two-stage pumps. The pumps develop their full speed in the range from atmosphere to Job vacancies in charlotte north carolina one torr. The speed then decreases to zero at their Job vacancies in charlotte north carolina pressures. Two of the most common designs are useful for pumping both liquids and gases. One is a two-bladed pump in which the rotor is eccentric to the stator, forming a crescent-shaped volume swept by the blades through the outlet valve. The second, a rotary piston pump, similar to a single blade, is part of the sleeve fitting around the rotor. The blade is hollow and acts as an inlet valve, closing off the pump from the system when the rotor is at top center. Ultimate pressures attainable are limited by leakage between the high and low-pressure sides of the pump due mainly to carry over of gases and Job vacancies in charlotte north carolina dissolved in the sealing oil that flash off when exposed to the low inlet pressure and decomposition of the oil exposed to high temperature spots generated by friction. Gas ballasting helps to prolong pump life because it removes the chief source of pump contamination, condensable vapors. The gas Job vacancies in charlotte north carolina is a vented exhaust that admits a small amount of air at atmospheric pressure to the compression side of the pump, thus permitting most condensable vapors to pass through the pump without condensing. Typical applications of this pump are in food packaging, high-speed centrifuges, and ultraviolet spectrometers. It is also widely used as a forepump or a roughing pump, or both, for most of the other pumps described. Capacities are available from 100 to 70, 000 cubic feet per minute, operating usually in the pressure range from 10 to 10 torr. The Job vacancies in charlotte north carolina speed of the pump is developed in the pressure range from 1 to 10 torr. The speed at the lower end of the Job vacancies in charlotte north carolina range depends on the type of forepump used.

Job vacancies in savannah ga

Okay, now you have found the leak. Here are some suggestions on how to fix it: Did You Find This Article Helpful? If so, a small donation even 1 would help underwrite the cost of maintaining this website, and allow us to provide even more free automotive content. To make a donation, use the button below and fill in an amount. Thanks! Need More Information about Engine Vacuum Leaks or Engine Troubleshooting? Try Google Search. Enter Keywords or a Phrase: Job vacancies in savannah ga Technology is the term applied to all processes and physical measurement carried out under conditions of below-normal atmospheric pressure. to remove the constituents of the atmosphere that could cause a physical or chemical reaction during the process, Job vacancies in savannah ga melting of reactive metals such as titanium to disturb an equilibrium condition that exists at normal room conditions such as the removal of occluded or dissolved gas or volatile liquid from the bulk of material, degassing of oils, freeze-drying or desorption of gas from surfaces, the cleanup of microwave tubes and Job vacancies in savannah ga accelerators during manufacture to Job vacancies in savannah ga the distance that a particle must travel before it collides with another, thereby helping the particles in a process to move without collision between source and target, in vacuum coating, particle accelerators, television picture tubes. to reduce the number of molecular impacts per second, thus reducing chances of contamination of surfaces prepared in vacuum, in clean-surface studies and preparation of pure, thin films. For any vacuum process, the limiting parameter for the maximum permissible pressure can be defined by: the number of molecules per unit volume reasons 1 and 2, the Job vacancies in savannah ga free path reason 3, or the time required to form a monolayer reason At room temperature and normal atmospheric pressure, one cubic foot 03 cubic metre of air contains approximately 7×10 molecules moving in random directions and at speeds of around 1, 000 miles per hour 1, 600 kilometers per hour. The momentum exchange imparted to the walls is equal to a force of 7 pounds for every square inch of wall Job vacancies in savannah ga This atmospheric pressure can be expressed in a number of different units see Table, but until recently it was commonly expressed in terms of the weight of a column of mercury of unit cross Job vacancies in savannah ga and 760 milimetres mm high. Thus, one standard atmosphere equals 760 mm Hg, but to avoid the anomaly of equating apparently different units, a term, torr, has been postulated. One standard atmosphere 760 torr 1 torr 1 mm Hg. This term was replaced in 1971 by SI unit defined as the newton per square metre N/m2, and called the pascal one pascal 5×10 The first major use of vacuum technology in industry occurred about Job vacancies in savannah ga in the manufacture of electric light bulbs. Other devices requiring a vacuum for their operation followed, such as various types of electron tube. Furthermore, it was discovered that certain processes carried out in a vacuum achieved either superior results, or ends that were unattainable under normal atmospheric conditions. Job vacancies in savannah ga developments included the blooming of lens surfaces to increase the light transmission, the preparation of blood plasma for blood banks, and the production of reactive metals such as titanium. The advent of nuclear energy in the 1950s provided impetus for development of vacuum equipment on a large scale. Increasing applications for vacuum processes were steadily discovered, as in space simulation and microelectronics. Industrial vacuum Job vacancies in savannah ga range from Job vacancies in savannah ga handling such as the manipulation of heavy and light items by suction pads to the deposition of integrated electronic circuits on silicon chips. Obviously, vacuum requirements are as widely varied as the particular processes using Job vacancies in savannah ga In the rough vacuum range from about one torr to near atmosphere, typical applications are Job vacancies in savannah ga handling, vacuum Job vacancies in savannah ga and forming, gas sampling, filtration, degassing of oils, concentration of aqueous solutions, impregnation of electrical components, distillation, and steel stream degassing. torr, many metallurgical processes such as melting, casting, sintering, heat treatment, and brazing can derive benefit. Chemical processes Job vacancies in savannah ga as vacuum distillation and freeze-drying also need this range of Job vacancies in savannah ga Freeze-drying is used extensively in the pharmaceutical industry to prepare vaccines and antibiotics and to store skin and blood plasma. The Job vacancies in savannah ga industry freeze-dries coffee mainly, although most foods can be stored without refrigeration after freeze-drying, and the technique is receiving widespread acceptance. torr is used for cryogenic low-temperature and electrical insulation. It is used in the production of lamps; television picture tubes, X-ray tubes; decorative, optical, and electrical thin-film coatings; and mass spectrometer leak detectors. In thin-film coating, a metal or compound is evaporated under high vacuum from a source onto a base material or substrate. The base material is generally plastic for decorative coatings; glass for optical coatings; and glass ceramic, or silica for electrical coatings. Thickness of the film can vary from about 1/4 wavelength of visible light to 001 inches or more.

Employment lawyer vacancy in east anglia

These machines feed artificial Employment lawyer vacancy in east anglia into the intake manifold, The smoke may also be mixed with an ultraviolet dye to make leaks easier to see. You then look for smoke seeping out of hoses, gaskets or cracks in the manifold and/or use a UV light to find the leak. This type of equipment is often needed to find small air leaks in the EVAP evaporative emissions control system. Smoke machines can cost 600 to 2000 or more depending on the model and features, so they are primarily for use by professional technicians. Propane can also be used in conjunction with an exhaust analyzer do NOT use carburetor cleaner or you may damage your analyzer!. Engine vacuum leaks almost always cause fluctuating HC readings, so an infrared exhaust analyzer can 1 tell you if there is indeed a leak, and 2 where the leak is using the propane procedure. Two types of vacuum leaks can be diagnosed with an analyzer. The first kind is a general vacuum leak PCV hose, brake booster, etc. that leans out the mixture and causes a very low CO reading and only a slightly higher fluctuating HC reading. The O2 reading will also be high. The second kind of vacuum leak is a point leak that affects only one or two cylinders a leaky manifold gasket or a crack or porosity leak in one of the manifold runners. This Employment lawyer vacancy in east anglia be indicated by a normal or low CO reading combined with high fluctuating HC readings. O2 will again be high. To find a leak, feed propane at suspected leak points until you note an improvement in Employment lawyer vacancy in east anglia quality and/or a change in the HC/CO/O2 readings. When you have found the leak, the idle should smooth out, HC and O2 should drop and CO rise. It is Employment lawyer vacancy in east anglia to note that an overly lean idle mixture will also cause a fluctuating HC reading the same as a vacuum leak. To tell one from the other, there is a simple trick you can use. Momentarily enrich the idle mixture to 5 to 0% CO by placing a clean shop rag over the top of the carburetor. If the engine smooths out and HC drops and remains stable, the problem is a lean idle mixture adjustment. If HC still fluctuates, however, the engine is still too lean in one or more cylinders indicating a vacuum leak. If you like gadgets, there are electronic tools designed to detect vacuum leaks. An electronic Employment lawyer vacancy in east anglia leak detector will beep or flash when it detects ultrasonic vibrations that are characteristic of a vacuum leak. These tools use a sensitive microphone to listen for certain noise frequencies. Though extremely sensitive, these tools sometimes react to tiny leaks that are not really causing a problem, or false leaks such as the noise created by arcing inside the distributor cap or normal bearing noise in the alternator. Another way to find an elusive vacuum leak is to pressurize the intake manifold with about three lbs. of regulated air. This can be done by attaching a regulator to your shop air hose, then attaching the hose to a vacuum fitting or the PCV valve fitting on the intake manifold, carburetor or throttle body. Do not apply too much pressure or you may create new leaks! With the engine off and air flowing into the manifold, spray soapy water on suspected leaks. If you see bubbles, you have found the leak. You can also use the opposite technique, which is to apply vacuum with a hand-pump to various vacuum hoses and circuits to see if they hold Employment lawyer vacancy in east anglia But this technique means tracing the entire circuit to see where it ends, and disconnecting and plugging any parts of the circuit that do not dead end against a diaphragm or valve.

Vacancies in the federal government

On older carbureted engines, vacuum is needed to pull fuel into the engine. Vacuum siphons fuel through the idle, main metering and power circuits. An engine with a vacuum leak, therefore, will likely be an engine that suffers from the symptoms of lean carburetion such as lean misfire, hesitation, stalling and rough idle. But the same symptoms can also be caused by a clogged catalytic converter or other exhaust restriction, a leaky EGR valve or valve timing problems all of which reduce intake vacuum. On most engines, intake vacuum should be steady between 16 and 22 inches Hg Mercury. A lower reading usually indicates a vacuum leak, or one of the other problems just mentioned. A reading that gradually drops while the engine is idling almost always points to an exhaust restriction. An oscillating vacuum reading usually indicates a leaky valve or badly worn valve guides that leak vacuum. Fuel injected engines do not require intake vacuum to siphon fuel into the engine Vacancies in the federal government fuel is sprayed directly into the engine Vacancies in the federal government pressure through the injectors. Even so, vacuum leaks can upset the carefully balanced air/fuel ratio by allowing unmetered air to enter the engine. The result is the same kind of driveability symptoms as a vacuum leak on a carbureted engine lean misfire, hesitation when accelerating, rough idle and possibly even Vacancies in the federal government Common leak points include injector O-rings, intake manifold gaskets, idle air control circuit and the throttle shaft. Fuel injected engines also rely on intake vacuum to regulate the fuel pressure behind the injectors. Fuel delivery cannot be accurately metered unless a fairly constant pressure differential is maintained. So the fuel pressure regulator diaphragm is connected to a source of intake vacuum. Vacuum working against a spring-loaded diaphragm inside the Vacancies in the federal government opens a bypass that shunts fuel back to the tank through a return line. This causes the fuel pressure in the injector rail to rise when engine load increases and vacuum drops. Thus, the regulator uses vacuum to Vacancies in the federal government fuel pressure and the correct air/fuel ratio. A vacuum leak changes the equation by causing a drop in vacuum and a corresponding increase in line pressure. Vacuum is measured with a vacuum gauge. Most are calibrated in inches Hg Mercury, but you may also see some gauges that are also calibrated in inches of H20 water or kilopascals kPa or even bars. One inch of vacuum measured in inches Hg equals 570 inches in H20, 4898 psi pounds per square inch or 377 kPa. Okay, now that we have covered what a vacuum leaks do, how do you find components that leak vacuum? One way is to visually inspect all the vacuum hoses and connections. Look for disconnected, loose or cracked hoses, broken fittings, etc. Hey, you might get lucky and find the problem in a few minutes, or you might waste half the day trying to find the mysterious leak. Vacuum leaks are often the elusive needle in a haystack. And if it is not a hose leaking vacuum but something else such as a gasket, worn throttle shaft, injector O-rings, etc. , you may never find it using this technique. A faster Vacancies in the federal government for finding intake manifold vacuum leaks is to get a bottle of propane and attach a length of rubber hose to the gas valve. Open the valve so you have a Vacancies in the federal government flow of gas. Then hold the hose near suspected leak points while the engine is idling. If there is a leak, propane will be siphoned in through the leak. The resulting correction in the engines air/fuel ratio should cause a noticeable change in idle speed and/or smoothness Note: on engines with computerized idle speed control, disconnect the idle speed control motor first. Aerosol carburetor cleaner can also be used the same way. CAUTION: Solvent is extremely flammable, so do not smoke or use it if there are any sparks in the vicinity arcing plug wires, for example. Spray the solvent on suspected leak points while the engine is idling. If there is a leak, the solvent will be drawn into the engine and have the same effect as the propane. The idle speed will suddenly change and smooth out. TIP: If you have a scan tool, look at the Short Term Fuel Trim STFT value while you are using carb cleaner or propane to check suspected vacuum leak points. If there is a leak and some of the cleaner or propane is sucked in through the leak, you will see a momentary drop in the STFT reading. This confirms you have found a leak keep checking because there may be multiple leaks!. A much safer technique is to use a smoke machine.

Vacancies in public schoolsf florida

So how do you know when a vacuum leak is causing a problem? If the engine is experiencing any of the following symptoms, a vacuum leak is probably responsible: Too fast an idle speed. If an engine without computerized idle speed control is idling too fast and refuses to come down to a normal idle speed despite your best efforts to back off the carburetor idle speed screw or air bypass adjustment screw fuel injection, air is getting past the throttle somewhere. Common leak paths include the carburetor and throttle body gaskets, carburetor insulator spacers, intake manifold gaskets, and of course, any of the engines vacuum fittings, hoses and accessories. It is even possible that leaky O-rings around the fuel injectors are allowing air to leak past the seals. Another overlooked item can be a worn throttle shaft. A rough idle or stalling. A performance cam with lots of valve overlap can give an engine a lopping idle, but so can a vacuum leak. A really serious leak can lean the air/fuel mixture out to such an extent that an engine wont idle at all. An EGR valve that is stuck open at idle can have the same effect as a vacuum leak. So too can the wrong PCV valve one that flows too much air for the application, or a loose PCV hose. The rough idle in these cases is caused by lean misfire. The fuel mixture is too lean to ignite reliably so it often misfires and fails to ignite at all. Lean misfire will show up as elevated hydrocarbon HC readings in the exhaust, enough, in fact, to cause a vehicle to fail an emissions test. Hesitation or misfiring when accelerating. This may be due to a vacuum leak, but it can also be caused by a weak or inoperative accelerator pump in a carburetor, dirty injectors, or even ignition problems such as a cracked coil, worn spark plugs or incorrectly gapped plugs. An idle mixture that defies adjustment. When setting the idle mixture adjustment screws on a carburetor, the idle speed should start to falter as the adjustment screws are turned in to lean out the mixture. If the screws seem to have little or no effect on idle, you have either got a carburetor problem or a vacuum leak. The important thing to keep in mind about vacuum leaks is that they have the most noticeable effect at idle. At part and full throttle, there is so much air entering the engine that a little extra air from a vacuum leak has a negligible effect. TIP: If you have a scan tool, look at the Short Term Fuel Trim STFT and Long Term Fuel Trim LTFT values. Normal range is plus or minus If the numbers are 10 or higher for STFT and LTFT, the engine is running LEAN. If you rev the engine to 1500 to 2000 rpm and hold it for a minute or so, and the STFT value drops back down to a more normal reading, it confirms the engine has a vacuum leak at idle. If the STFT value does not change much, the lean fuel condition is more likely a fuel delivery problem weak fuel pump, restricted fuel filter, dirty fuel injectors or a leaky fuel pressure regulator than a vacuum leak. For more information about using fuel trim to diagnose a lean fuel condition, read this article on Fuel Trim by Wells Manufacturing PDF file, requires Adobe Acrobat to read. Before we get into the various techniques of finding and fixing vacuum leaks, lets quickly review vacuum s role in fuel delivery. Intake vacuum exists in the intake manifold as a result of the pumping action of the engines pistons and the restriction created by the throttle valve. Were it not for the throttle choking off the flow of air into the engine, there would be little if any vacuum in the intake manifold like a diesel.