Toyota has created a new power unit based on the 4A-FE. Unlike the main model, the 7a engine has a larger combustion chamber (1.8 instead of 1.6 liters) with different characteristics. This parameter reaches its maximum value when the engine crankshaft rotates at a speed of 2800 rpm. Thanks to its unique characteristics, fuel is significantly saved, efficiency increases, and the car quickly picks up speed. Drivers appreciated the advantages of the Toyota 7A engine when driving in difficult conditions of city streets with traffic jams and frequent stops at traffic lights.

7A FE motor application area

As a result of successful test trials, and also, thanks to the large number positive feedback car owners, Japanese automakers decided to install of this engine on manufactured Toyota models. The Japanese 7A FE engine is widely used in the manufacture of class C cars:

• Avensis;
• Caldina;
• Carina;
• Carina E;
• Celica;
• Corolla/Conquest;
• Corolla;
• Corolla/Prizm;
• Corolla Spacio;
• Crown;
• Corona Premium;
• Sprinter Carib.

Car Crown Premium 1996 engine 7A

Premium is the second name for first generation cars Toyota Crown, released earlier. To increase sales, manufacturers changed the interior design, appearance and names of branded cars. The updated vehicle is equipped with an engine with D-4 direct injection.

Technical characteristics of the 7A FE engine

This motor was in production for several years, from 1990 to 2002.

1. Maximum engine power fe – 120 hp. With.
2. The volume of the working cylinders is 1762 cm3.
3. Developed torque – 157 N.m during rotation crankshaft 4400 rpm
4. The piston stroke length is 85.5 mm.
5. The radius of the cylinders is 40.5 mm.
6. The cylinder block material is cast iron alloy.
7. Cylinder heads are aluminum alloy.
8. Gas distribution system – DOHC.
9. Type of fuel - gasoline.

Features of the 7A-FE engine design

In parallel with the 7A-FE, an engine labeled 7A-FE Lean Burn was created. Advantage additional modification lies in its greatest efficiency. Gasoline is thoroughly mixed with oxygen in the variable intake manifold, which significantly improves the combustion efficiency of the air-fuel mixture.

Thanks to the systems electronic control, the mixtures are enriched or leaned within the specified parameters, which increases engine efficiency. Judging by numerous reviews from owners of cars equipped with 7A-FE Lean Burn, the engine has record low fuel consumption.

The main differences between the new modifications of 7A engines:

1. The use of a manifold with flaps to adjust the degree of enrichment of air-fuel mixtures towards a decrease.
2. Activation of the “lean mode” under the control of the electronic system.
3. Location of nozzles.
4. Use of special spark plugs coated with platinum.

Excellent specifications and high efficiency of 7A is ensured thanks to operation at lean fuel-air mixtures(lean burn). Most often, 7A engines can be found on Toyota models (Karina, Kaldina). The design of the intake manifold, the so-called “lean” version 7A-FE, uses special flaps that change the amount of oxygen in the mixture when the power unit is operated under normal conditions without increased loads. At the same time, there is a slight decrease in engine power, approximately by 5 Horse power, as well as improving environmental performance.

Using an electronic control system, the transition to a lean mixture occurs in automatic mode. When the 7A-FE engine is idling, the electronics do not control the oxygen supply. Depending on the position of the automatic transmission selector, electronic system engine control quickly responds to control input from the driver and turns the lean mode on/off.

The injectors for the 7A-FE engine open one by one, serving each cylinder separately. They are recessed directly into the valve body cover.

Thanks to the inclusion of a contactless DIS-2 ignition system in the design of this engine, there is no need to adjust the ignition angle. For this purpose, the electronics use a knock sensor.

To successfully ignite a lean mixture with a Lean Burn device, higher quality sparking is required. When using gasoline of inappropriate quality, a layer of soot forms on the spark plugs. If the spark plugs are acting up, the engine begins to jerk and stall both when driving and at idle. Toyota has decided to replace conventional spark plugs with platinum-coated products. To get more powerful spark The design of the spark plugs also includes two electrodes with a gap of 1.3 mm.

Interesting: It was noticed that when Toyota 7A-FE engines operate on fuel Russian made, expensive platinum candles become coated and do not produce the promised potential. Instead of the expected 60,000 kilometers, they travel only 5,000. A solution has been found. folk craftsmen. They use regular spark plugs without expensive coating and have a 1.1mm gap. Before installation, simply extend the electrodes by 1.3 mm, increasing the gap to improve the spark. If you use a gap of 1.1 mm, lean system burn does not save gasoline; its consumption increases noticeably. Experts advise installing NGK spark plugs BKR5EKB-11 with separated electrodes instead of the recommended NGK BKR5EKPB-13.

Toyota produces engines of this modification, designed for regular fuel. This is gasoline Japanese made, his octane number corresponds to our unleaded AI-92. Unlike 92-grade gasoline, AI-95 contains numerous additives that negatively affect spark plugs. Therefore, it is recommended to fill the 7A-FE engine with AI-92 gasoline.

Replacing the timing belt in the 7A FE engine

The timing belt of the 7A FE engine is designed to drive and synchronize the rotation of the camshaft and crankshaft. If it breaks, the cyclical functions of the engine systems internal combustion completely lost. At the same time there is high probability serious consequences leading to major renovation vehicle.

In order to save the internal combustion engine and the car as a whole from serious damage It is recommended to check the technical condition of the timing belt. If necessary, it is replaced.

In accordance with the automaker's recommendations, the timing belt in the 7A FE engine needs to be changed after a mileage of 100,000 kilometers. Taking into account the operating conditions of machines in difficult domestic roads, experienced motorists advise doing this much earlier - after 80,000 km.

Thanks to the large number step by step instructions, posted on the Internet in the form of detailed videos, these activities can be performed independently in a garage. The main condition is accuracy and strict adherence to the sequence of operations.

Algorithm for replacing the belt:

1. Disconnect the battery terminals.
2. Remove spark plugs.
3. Remove the alternator belt.
4. Valve cover.
5. Unscrew the fastening parts of the upper timing belt cover and remove it.
6. Carefully inspect the condition of the belt to see if there are any cracks or other damage on its surface.
7. Remove the belt.
8. At the same time as the belt, the following are removed: tension and deflection rollers, which should not be damaged.
9. If even the slightest scratches are noticed on the surfaces of the rollers, they must also be replaced.
10. Components are replaced with new units. Selected from the catalog of spare parts for the 7A-FE engine.
11. Install new belt Timing belt, providing the necessary sag.
12. When fixing the bolts, the recommended tightening torque is used.
13. Install the cover and other components in reverse order.

Important: After connecting and tightening the battery terminals, it is advisable to leave a mark on the top cover about the date of replacement of the timing belt and the number of kilometers traveled at this time.

When developing the design of this engine, it is provided important point– the likelihood of a joint impact of pistons and valves in the event of a possible break in the timing belt is minimized. In this case, the possibility of bending of the valves is accordingly excluded. This significantly increases the reliability level of the 7A engine.

Is engine tuning possible – Toyota 7A FE

To increase the acceleration dynamics of a car, a turbine is included in the engine design. With the help of turbocharging the coefficient increases useful action power unit, the car accelerates better from a standstill. Such engine improvements will come in handy during frequent trips on city streets with difficult conditions movement in start-stop mode.

Reliable Japanese engines

04.04.2008

The most common and by far the most widely repaired of the Japanese engines is the Toyota series 4, 5, 7 A - FE engine. Even a novice mechanic or diagnostician knows about possible problems engines of this series.

I will try to highlight (gather into a single whole) the problems of these engines. There are not many of them, but they cause a lot of trouble for their owners.

Date from scanner:

On the scanner you can see a short but capacious date consisting of 16 parameters, by which you can really evaluate the operation of the main engine sensors.
Sensors:

Oxygen sensor - Lambda probe

Many owners turn to diagnostics due to increased fuel consumption. One of the reasons is a simple break in the heater in the oxygen sensor. The error is recorded by the control unit code number 21.

The heater can be checked with a conventional tester on the sensor contacts (R- 14 Ohm)

Fuel consumption increases due to the lack of correction during warming up. You will not be able to restore the heater - only replacement will help. The cost of a new sensor is high, and it makes no sense to install a used one (their service life is long, so it’s a lottery). In such a situation, less reliable ones can be installed as an alternative. universal sensors NTK.

Their service life is short, and their quality leaves much to be desired, so such a replacement is a temporary measure and should be done with caution.

When the sensitivity of the sensor decreases, fuel consumption increases (by 1-3 liters). The performance of the sensor is checked with an oscilloscope on the block diagnostic connector, or directly on the sensor chip (number of switchings).

temperature sensor

If not proper operation The owner of the sensor will face a lot of problems. If the sensor's measuring element breaks, the control unit replaces the sensor readings and records its value at 80 degrees and records error 22. The engine, with such a malfunction, will operate in normal mode, but only while the engine is warm. As soon as the engine cools down, it will be difficult to start it without doping, due to the short opening time of the injectors.

There are often cases when the resistance of the sensor changes chaotically when the engine is running at idle. – the speed will fluctuate.

This defect can be easily detected on a scanner by observing the temperature reading. On a warm engine it should be stable and not change randomly from 20 to 100 degrees.

With such a defect in the sensor, a “black exhaust” is possible, unstable operation on the exhaust gas. and as a consequence, increased consumption, as well as the impossibility of starting “hot”. Only after a 10 minute standstill. If not full confidence If the sensor is working properly, its readings can be replaced by connecting a 1k or a constant 300ohm resistor into its circuit for further testing. By changing the sensor readings, the change in speed at different temperatures is easily controlled.

Position sensor throttle valve

Many cars go through the assembly and disassembly procedure. These are the so-called “designers”. When removing the engine in field conditions and subsequent assembly, the sensors on which the engine is often leaned suffer. If the TPS sensor breaks, the engine stops throttling normally. The engine choke when revving up. The automatic shifts incorrectly. The control unit records error 41. When replacing, the new sensor must be configured so that the control unit correctly sees the sign of Х.Х. when the gas pedal is fully released (the throttle valve is closed). In the absence of the idle speed sign, adequate regulation of the flow rate will not be carried out. and there will be no forced idling mode during engine braking, which again will entail increased fuel consumption. On 4A, 7A engines, the sensor does not require adjustment; it is installed without the possibility of rotation.
THROTTLE POSITION……0%
IDLE SIGNAL……………….ON

Sensor absolute pressure MAP

This sensor is the most reliable of all installed on Japanese cars. His reliability is simply amazing. But it also has its fair share of problems, mainly due to improper assembly.

Either the receiving “nipple” is broken, and then any passage of air is sealed with glue, or the tightness of the supply tube is broken.

With such a gap, fuel consumption increases, the level of CO in the exhaust increases sharply to 3%. It is very easy to observe the operation of the sensor using a scanner. The INTAKE MANIFOLD line shows the vacuum in the intake manifold, which is measured by the MAP sensor. If the wiring is broken, the ECU registers error 31. At the same time, the opening time of the injectors sharply increases to 3.5-5 ms. When over-gasping, a black exhaust appears, the spark plugs are seated, and shaking appears at idle. and stopping the engine.

Knock sensor

The sensor is installed to register detonation knocks (explosions) and indirectly serves as a “corrector” for the ignition timing. The recording element of the sensor is a piezoelectric plate. If the sensor malfunctions, or the wiring is broken, at revs over 3.5-4 tons, the ECU records error 52. Sluggishness is observed during acceleration.

You can check the functionality with an oscilloscope, or by measuring the resistance between the sensor output and the housing (if there is resistance, the sensor requires replacement).

Crankshaft sensor

7A series engines have a crankshaft sensor. A conventional inductive sensor is similar to the ABC sensor and is practically trouble-free in operation. But embarrassments also happen. When an interturn short circuit occurs inside the winding, the generation of pulses is disrupted at certain speeds. This manifests itself as a limitation of engine speed in the range of 3.5-4 rpm. A kind of cut-off, only on low revs. Detecting an interturn short circuit is quite difficult. The oscilloscope does not show a decrease in pulse amplitude or a change in frequency (during acceleration), and it is quite difficult to notice changes in Ohm fractions with a tester. If symptoms of rev limiting occur at 3-4 thousand, simply replace the sensor with a known good one. In addition, a lot of trouble is caused by damage to the drive ring, which is damaged by careless mechanics when carrying out replacement work. front oil seal crankshaft or timing belt. By breaking the teeth of the crown and restoring them by welding, they achieve only a visible absence of damage.

In this case, the crankshaft position sensor ceases to adequately read information, the ignition timing begins to change chaotically, which leads to a loss of power, unstable work engine and increased fuel consumption

Injectors (nozzles)

Over many years of operation, the nozzles and needles of the injectors become covered with resins and gasoline dust. All this naturally disrupts the correct spray pattern and reduces the performance of the nozzle. With severe contamination, noticeable engine shaking is observed and fuel consumption increases. It is possible to determine clogging by conducting a gas analysis; based on the oxygen readings in the exhaust, one can judge whether the filling is correct. A reading above one percent will indicate the need to flush the injectors (if correct installation timing and normal fuel pressure).

Either by installing the injectors on a stand and checking the performance in tests. The nozzles are easy to clean with Laurel and Vince, both in CIP installations and in ultrasound.

Idle valve, IACV

The valve is responsible for engine speed in all modes (warm-up, idling, load). During operation, the valve petal becomes dirty and the stem becomes jammed. The revolutions hang during warm-up or at idle (due to the wedge). Tests for changes in speed in scanners during diagnostics using this motor not provided. You can evaluate the performance of the valve by changing the readings of the temperature sensor. Put the engine into “cold” mode. Or, after removing the winding from the valve, twist the valve magnet with your hands. The jamming and wedge will be noticeable immediately. If it is impossible to easily dismantle the valve winding (for example, on the GE series), you can check its functionality by connecting to one of the control terminals and measuring the duty cycle of the pulses while simultaneously monitoring the idle speed. and changing the load on the engine. On a fully warmed-up engine, the duty cycle is approximately 40%; by changing the load (including electrical consumers), you can estimate an adequate increase in speed in response to a change in duty cycle. When the valve is mechanically jammed, there is a smooth increase in the duty cycle, which does not entail a change in the rotation speed.

You can restore operation by cleaning off carbon deposits and dirt with a carburetor cleaner with the windings removed.

Further adjustment of the valve consists of setting the idle speed. On a fully warmed-up engine, by rotating the winding on the mounting bolts, achieve the table speed for of this type car (according to the tag on the hood). Having previously installed the jumper E1-TE1 in the diagnostic block. On “younger” 4A, 7A engines the valve was changed. Instead of the usual two windings, a microcircuit was installed in the body of the valve winding. We changed the valve power supply and the color of the plastic winding (black). It is already pointless to measure the resistance of the windings at the terminals.

Power and control signal are supplied to the valve rectangular shape variable duty cycle.

To make it impossible to remove the winding, they installed non-standard fasteners. But the wedge problem remained. Now if you clean with a regular cleaner, the grease is washed out of the bearings (the further result is predictable, the same wedge, but because of the bearing). You should completely remove the valve from the throttle valve block and then carefully wash the stem and petal.

Ignition system. Candles.

Very large percentage cars come to the service center with problems in the ignition system. When operating on low-quality gasoline The spark plugs are the first to suffer. They become covered with a red coating (ferrosis). There will be no high-quality spark formation with such spark plugs. The engine will run intermittently, with misfires, fuel consumption increases, and the level of CO in the exhaust rises. Sandblasting cannot clean such candles. Only chemistry (lasts for a couple of hours) or replacement will help. Another problem is increased clearance (simple wear).

Drying rubber tips high voltage wires, water that gets in when washing the engine, which all provoke the formation of a conductive path on the rubber tips.

Because of them, sparking will not be inside the cylinder, but outside it.
With smooth throttling, the engine runs stably, but with sharp throttling, it “splits”.

In this situation, it is necessary to replace both the spark plugs and the wires at the same time. But sometimes (in field conditions) if replacement is impossible, you can solve the problem with an ordinary knife and a piece of sandstone (fine fraction). Use a knife to cut off the conductive path in the wire, and use a stone to remove the strip from the ceramic of the candle.

It should be noted that you cannot remove the rubber band from the wire, this will lead to complete inoperability of the cylinder.

Another problem is related to the incorrect procedure for replacing spark plugs. The wires are forcefully pulled out of the wells, tearing off the metal tip of the reins.

With such a wire, misfires and floating speed are observed. When diagnosing the ignition system, you should always check the performance of the ignition coil on a high-voltage spark gap. The most simple check– with the engine running, check the spark at the spark gap.

If the spark disappears or becomes thread-like, this indicates an interturn short circuit in the coil or a problem in the high-voltage wires. Wire breakage is checked with a resistance tester. A small wire is 2-3k, then a longer wire is 10-12k.

The resistance of the closed coil can also be checked with a tester. The resistance of the secondary winding of the broken coil will be less than 12k.
The next generation coils do not suffer from such ailments (4A.7A), their failure is minimal. Proper cooling and the thickness of the wire eliminated this problem.
Another problem is the leaking seal in the distributor. Oil getting on the sensors corrodes the insulation. And when exposed high voltage The slider is oxidized (covered with a green coating). The coal turns sour. All this leads to a breakdown in spark formation.

Chaotic shootings are observed in motion (in intake manifold, into the muffler) and crushing.

" Thin " malfunctions Toyota engine

On modern engines Toyota 4A, 7A, the Japanese changed the firmware of the control unit (apparently for more quick warm-up engine). The change is that the engine reaches idle speed only at a temperature of 85 degrees. The design of the engine cooling system was also changed. Now a small cooling circle intensively passes through the head of the block (not through the pipe behind the engine, as was before). Of course, the cooling of the head has become more efficient, and the engine as a whole has become more efficient in cooling. But in winter, with such cooling, when driving, the engine temperature reaches 75-80 degrees. And as a result, constant warm-up speeds (1100-1300), increased fuel consumption and nervousness of the owners. You can deal with this problem either by insulating the engine more, or by changing the resistance of the temperature sensor (by deceiving the ECU).

Oil

Owners pour oil into the engine indiscriminately, without thinking about the consequences. Few people understand that Various types oils are incompatible and when mixed they form an insoluble mess (coke), which leads to complete destruction of the engine.

All this plasticine cannot be washed off with chemicals; it can only be cleaned mechanically. It should be understood that if it is unknown what type of old oil is, then you should use flushing before changing. And one more piece of advice for owners. Pay attention to the color of the handle oil dipstick. It is yellow in color. If the color of the oil in your engine is darker than the color of the handle, it’s time to change it, rather than wait for the virtual mileage recommended by the engine oil manufacturer.

Air filter

The most inexpensive and easily accessible element is the air filter. Owners very often forget about replacing it, without thinking about the likely increase in fuel consumption. Often due to clogged filter The combustion chamber becomes very dirty with burnt oil deposits, the valves and spark plugs become very dirty.

When diagnosing, you may mistakenly assume that wear is to blame. valve stem seals, but the root cause is a clogged air filter, which increases the vacuum in the intake manifold when dirty. Of course, in this case the caps will also have to be changed.

Some owners don’t even notice that they live in the building air filter garage rodents. Which speaks volumes about their complete disregard for the car.

Fuel filteralso deserves attention. If it is not replaced in time (15-20 thousand mileage), the pump begins to work with overload, the pressure drops, and as a result, the need to replace the pump arises.

Plastic parts of pump impeller and check valve wear out prematurely.

Pressure drops

It should be noted that the motor can operate at a pressure of up to 1.5 kg (with a standard pressure of 2.4-2.7 kg). With reduced pressure, constant shooting into the intake manifold is observed; starting is problematic (afterwards). The draft is noticeably reduced. It is correct to check the pressure with a pressure gauge. (access to the filter is not difficult). In field conditions, you can use the “return flow test”. If, when the engine is running, less than one liter of gasoline flows out of the return hose in 30 seconds, we can judge that the pressure is low. You can use an ammeter to indirectly determine the pump's performance. If the current consumed by the pump is less than 4 amperes, then the pressure is lost.

You can measure the current on the diagnostic block.

When using a modern tool, the filter replacement process takes no more than half an hour. Previously, this took a lot of time. Mechanics always hoped that they would be lucky and the lower fitting would not rust. But this is often what happened.

I had to rack my brain for a long time about which gas wrench to use to hook the rolled-up nut of the lower fitting. And sometimes the process of replacing the filter turned into a “movie show” with the removal of the tube leading to the filter.

Today no one is afraid to make this replacement.

Control block

Until 1998 release, the control units did not have enough serious problems during operation.

The blocks had to be repaired only because" hard polarity reversal" . It is important to note that all terminals of the control unit are signed. It’s easy to find the required sensor pin for testing on the board, or wire continuity. The parts are reliable and stable in operation at low temperatures.
In conclusion, I would like to dwell a little on gas distribution. Many “hands-on” owners perform the belt replacement procedure on their own (although this is not correct, they cannot tighten the crankshaft pulley correctly). Mechanics produce quality replacement for two hours (maximum) If the belt breaks, the valves do not meet the piston and fatal destruction of the engine does not occur. Everything is calculated down to the smallest detail.

We tried to talk about the most frequently occurring problems on Toyota A series engines. The engine is very simple and reliable and subject to very harsh operation on “water-iron gasoline” and dusty roads of our great and mighty Motherland and the “maybe” mentality of the owners. Having endured all the bullying, he continues to delight with his reliable and stable work, having won the status of the best Japanese engine.

We wish everyone the fastest possible identification of problems and easy repairs. Toyota engine 4, 5, 7 A - FE!

Vladimir Bekrenev, Khabarovsk
Andrey Fedorov, Novosibirsk
© Legion-Avtodata

UNION OF AUTOMOBILE DIAGNOSTICS

You will find information on car maintenance and repair in the book(s):

(Lean Bum) refers to low-speed power units characterized by a high degree of torque. IN serial production, such engines were designed for installation in Japanese passenger cars Corolla family. A little later, these power units found their use in the Caldina and Carina line of cars, and were equipped with a Lean Bum power system, which works very successfully with lean fuel mixtures, which significantly increased the level of fuel economy of cars intended for constant movement in city ​​conditions, associated with frequent standing in traffic jams.

Unfortunately, after the appearance Japanese cars, in which it was installed engine 7a, in the territory of the post-Soviet space, one could hear frequent complaints addressed to them about the inadequate work of the mentioned fuel system, manifested in failures of the gas pedal, especially at medium engine speeds. Install exact reason What is happening, sometimes, even specialists do not understand. Some say it's all to blame low quality fuel used, others blame for what is happening automotive systems ignition and power, which are in the data vehicles very sensitive to technical condition spark plugs and high-voltage wires. One way or another, but practice knows cases when depleted fuel mixture It just didn't set fire.

In addition to the above, the disadvantages of 7a engines include difficulties arising when adjusting the intake valves, piston pins that do not “float”, and premature wear camshafts. Although, in general, the power unit is 7a, the device is quite reliable and easy to operate, maintain, and repair.

Engine 7a belongs to engines of a later modification, having an increased displacement in comparison with power units 4a and 5a (FE). His distinctive feature is very good mechanics. It is completely repairable, and this unit has never had any problems with spare parts. Very often malfunctions power units 7a occur due to the failure of any of the numerous sensors. Particular attention should be paid to the oxygen sensor, temperature sensor engine, and throttle sensor. When replacing them, it is recommended to install only original devices, in particular Denso, although Bosch and NTK products are also suitable.