Reliable Japanese engines

04.04.2008

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

I will try to highlight (put together) the problems of these engines. There are few of them, but they cause a lot of trouble to their owners.

Date from scanner:

On the scanner, you can see a short but capacious date, consisting of 16 parameters, by which you can realistically 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 banal break in the heater in the oxygen sensor. The error is fixed by the code control unit 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 operating life is large, so this is a lottery). In such a situation, the less reliable NTK universal sensors can be installed as an alternative.

Their service life is short, and the quality is poor, so such a replacement is a temporary measure, and it should be done with caution.

With a decrease in the sensitivity of the sensor, an increase in fuel consumption occurs (by 1-3 liters). The performance of the sensor is checked with an oscilloscope on the diagnostic connector block, or directly on the sensor chip (number of switchings).

temperature sensor

If the sensor does not work properly, the owner will face a lot of problems. If the measuring element of the sensor breaks down, the control unit replaces the sensor readings and fixes its value at 80 degrees and fixes error 22. The engine, in case of such a malfunction, will work in normal mode, but only while the engine is warm. Once the engine has cooled down, it will be problematic to start it without doping, due to the short opening time of the injectors.

It is not uncommon for the resistance of the sensor to change chaotically when the engine is running on H.H. - the revolutions will float.

This defect can be easily fixed on the 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, "black exhaust" is possible, unstable operation on the Х.Х. and, as a consequence, increased consumption, as well as the impossibility of starting "hot". Only after 10 minutes of rest. If there is no complete confidence in the correct operation of the sensor, its readings can be substituted by including a variable resistor of 1kΩ in its circuit, or a constant 300Ω, for further verification. By changing the sensor readings, it is easy to control the change in speed at different temperatures.

Throttle position sensor

A lot of cars go through the disassembly assembly procedure. These are the so-called "constructors". When removing the engine in the field and subsequent assembly, the sensors suffer, on which the engine is often leaned against. If the TPS sensor breaks, the engine stops throttling normally. The engine chokes when accelerating. The machine switches incorrectly. The control unit registers error 41. When replacing a new sensor, it is necessary to adjust so that the control unit correctly sees the X.X sign when the gas pedal is fully released (throttle valve closed). In the absence of a sign of idling, adequate regulation of the Х.Х will not be carried out. and there will be no forced idling during engine braking, which again will entail increased fuel consumption. On engines 4A, 7A, the sensor does not require adjustment, it is installed without the possibility of rotation.
THROTTLE POSITION …… 0%
IDLE SIGNAL ……………… .ON

MAP absolute pressure sensor

This sensor is the most reliable ever installed on Japanese cars. Its reliability is simply amazing. But it also has a lot 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 violated.

With such a rupture, fuel consumption increases, the level of CO in the exhaust rises sharply up to 3%. It is very easy to observe the operation of the sensor using a scanner. The line INTAKE MANIFOLD 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 increases sharply to 3.5-5 ms. During gas re-gasings, a black exhaust appears, the candles are planted, there is a shaking on the X.X. and stopping the engine.

Knock sensor

You can check the operability with an oscilloscope, or by measuring the resistance between the sensor terminal and the case (if there is resistance, the sensor needs to be replaced).

Crankshaft sensor

A crankshaft sensor is installed on the 7A series engines. A conventional inductive sensor, similar to the ABC sensor, is practically trouble-free in operation. But embarrassment also happens. With an interturn short circuit 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 t. Revolutions. A kind of cutoff, only at low revs. It is quite difficult to detect an interturn short circuit. The oscilloscope does not show a decrease in the amplitude of pulses or a change in frequency (with acceleration), and it is rather difficult to notice changes in Ohm fractions with a tester. If symptoms of speed limitation occur at 3-4 thousand, just replace the sensor with a known good one. In addition, a lot of trouble is caused by damage to the driving ring, which is damaged by careless mechanics when they replace the front crankshaft oil seal or timing belt. Having broken the teeth of the crown, and restoring them by welding, they achieve only a visible absence of damage.

At the same time, the crankshaft position sensor ceases to adequately read information, the ignition timing begins to change chaotically, which leads to a loss of power, unstable engine operation and an increase in fuel consumption

Injectors (nozzles)

During many years of operation, the nozzles and needles of the injectors are covered with resins and gasoline dust. All this naturally interferes with the correct spray pattern and reduces the performance of the nozzle. In case of severe contamination, a noticeable shaking of the engine is observed, and fuel consumption increases. It is really possible to determine the clogging by conducting a gas analysis, according to the oxygen readings in the exhaust, it is possible to judge the correctness of the filling. A reading over one percent will indicate the need to flush the injectors (with the correct timing and normal fuel pressure).

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

Idle valve, IACV

The valve is responsible for the engine speed in all modes (warm-up, idle, load). During operation, the valve petal becomes dirty and the stem wedges. The revolutions freeze on heating or on HH (due to a wedge). There are no tests for changing the speed in scanners when diagnosing this motor. You can evaluate the valve's performance by changing the readings of the temperature sensor. Put the engine in "cold" mode. Or, removing the winding from the valve, twist the valve magnet with your hands. Sticking and wedge will be felt immediately. If it is impossible to easily dismantle the valve winding (for example, on the GE series), you can check its operability by connecting to one of the control outputs and measuring the duty cycle of the pulses while simultaneously monitoring the H.X. speed. and changing the load on the engine. On a fully warmed-up engine, the duty cycle is approximately 40%, changing the load (including electrical consumers), it is possible to estimate an adequate increase in speed in response to a change in the duty cycle. With mechanical jamming of the valve, there is a smooth increase in the duty cycle, which does not entail a change in the speed of H.H.

You can restore work by cleaning carbon deposits and dirt with a carburetor cleaner with the winding removed.

Further adjustment of the valve is to set the H.H. speed. On a fully warmed-up engine, by rotating the winding on the mounting bolts, they achieve tabular revolutions for this type of car (according to the tag on the hood). By pre-installing the jumper E1-TE1 in the diagnostic block. On the "younger" motors 4A, 7A, the valve was changed. Instead of the usual two windings, a microcircuit was installed in the body of the valve winding. Changed the valve power and the color of the winding plastic (black). It is already pointless to measure the resistance of the windings at the terminals on it.

The valve is supplied with power and a square-wave variable duty cycle control signal.

For the impossibility of removing the winding, non-standard fasteners were installed. But the problem of the wedge remained. Now if you clean it with an ordinary cleaner, the grease is washed out from the bearings (the further result is predictable, the same wedge, but due to the bearing). It is necessary to completely dismantle the valve from the throttle body and then carefully flush the stem with a petal.

Ignition system. Candles.

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

Drying of the rubber tips of high-voltage wires, water that got in during the washing of the motor, which all provoke the formation of a conductive track on the rubber tips.

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

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

It should be noted that it is impossible to remove the rubber band from the wire, this will lead to the complete inoperability of the cylinder.

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

With such a wire, misfires and floating revolutions are observed. When diagnosing the ignition system, always check the performance of the ignition coil on the high-voltage spark gap. The simplest check is to look at the spark on the spark gap while the engine is running.

If the spark disappears or becomes threadlike, 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. Small wire 2-3kom, further to increase the long 10-12kom.

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

In motion, chaotic lumbago is observed (into the intake manifold, into the muffler) and crushing.

" Thin " malfunctions Toyota engine

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

Butter

Owners pour oil into the engine indiscriminately, without thinking about the consequences. Few people understand that different types of oils are not compatible and, when mixed, form an insoluble slurry (coke), which leads to the complete destruction of the engine.

All this plasticine cannot be washed off with chemistry, it can only be cleaned out mechanically. It should be understood that if you do not know what type of old oil, then you should use flushing before changing. And more advice to the owners. Pay attention to the color of the dipstick handle. 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 make a change, and not wait for the virtual mileage recommended by the engine oil manufacturer.

Air filter

The most inexpensive and readily available element is the air filter. Owners very often forget about replacing it, without thinking about the likely increase in fuel consumption. Often, due to a clogged filter, the combustion chamber is very heavily contaminated with burned oil deposits, valves and candles are heavily contaminated.

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

Some owners do not even notice about garage rodents living in the air filter housing. Which speaks of their utter disregard for the car.

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

The plastic parts of the pump impeller and non-return valve wear prematurely.

Pressure drops

It should be noted that the operation of the motor is possible at a pressure of up to 1.5 kg (with a standard 2.4-2.7 kg). At reduced pressure, there are constant lumbago in the intake manifold, the start is problematic (after). Draft is noticeably reduced. Check pressure correctly with a pressure gauge. (access to the filter is not difficult). In the field, you can use the "return filling test". If, when the engine is running, less than one liter flows out of the gasoline return hose in 30 seconds, it is possible to judge the reduced pressure. 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 sagged.

You can measure the current on the diagnostic block.

I had to puzzle for a long time with which gas wrench to hook the rolled 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

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

The blocks had to be repaired only for a reason" hard polarity reversal" ... It is important to note that all outputs of the control unit are signed. It is easy to find on the board the required sensor lead to check, or wire rings. The parts are reliable and stable in operation at low temperatures.
In conclusion, I would like to dwell a little on gas distribution. Many owners "with hands" perform the belt replacement procedure on their own (although this is not correct, they cannot properly tighten the crankshaft pulley). The mechanics will make a quality replacement within two hours (maximum). If the belt breaks, the valves do not meet the piston and the engine will not be fatally destroyed. Everything is calculated to the smallest detail.

We tried to tell you about the most common problems on Toyota A series engines. The engine is very simple and reliable, and subject to very tough operation on “water-iron gasoline” and dusty roads of our great and mighty Motherland and the “awkward” mentality of the owners. Having endured all the bullying, it continues to delight to this day with its reliable and stable work, having won the status of the best Japanese engine.

All the early identification of problems and easy repair of the Toyota 4, 5, 7 A - FE engine!

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

UNION OF AUTOMOTIVE DIAGNOSIS

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

Toyota 5A-F / FE / FHE 1.5 liter engine.

Toyota 5A engine specifications

Production	Kamigo Plant Shimoyama plant Deeside Engine Plant North Plant Tianjin FAW Toyota Engine's Plant No. 1
Engine brand	Toyota 5A
Years of release	1987-present
Cylinder block material	cast iron
Supply system	carburetor / injector
Type of	inline
Number of cylinders	4
Valves per cylinder	4
Piston stroke, mm	77
Cylinder diameter, mm	78.7
Compression ratio	9.8
Engine displacement, cubic cm	1498
Engine power, hp / rpm	85/6000 100/5600 105/6000 120/6000
Torque, Nm / rpm	122/3600 138/4400 131/4800 132/4800
Fuel	92
Environmental standards	-
Engine weight, kg	-
Fuel consumption, l / 100 km (for Carina) - town - track - mixed.	6.8 4.0 5.0
Oil consumption, gr. / 1000 km	up to 1000
Engine oil	5W-30 10W-30 15W-40 20W-50
How much oil is in the engine	3.0
Oil change is carried out, km	10000 (better than 5000)
Engine operating temperature, deg.	-
Engine resource, thousand km - according to the plant - on practice	n.d. 300+
Tuning - potential - without loss of resource	n.d. n.d.
The engine was installed	Toyota Corolla Ceres Toyota G Touring Toyota Sprinter Toyota Sprinter Marino Toyota Tercel Toyota Vios FAW Xiali Weizhi

Faults and engine repair 5A-F / FE / FHE

The Toyota 5A engine is an analogue of the 4A engine, in which the cylinder diameter is reduced from 81 mm to 78.7 mm, thus a volume of 1500 cc is obtained. Otherwise, we have the same 4A-F / FE / FHE, with all its pros and cons. The usual civilian engine, sports versions of GE / GZE based on the 5A were not developed.

Toyota 5A engine modifications

1.5A-F - carburetor version, analogue of 4A-F with reduced volume. Compression ratio 9.8, power 85 hp. The engine was in production from 1987 to 1990.
2 ... 5A-FE - analogue of 4A-FE, is a 5A-F with electronic fuel injection, compression ratio 9.6, power 105 hp. The production of the engine was started in 1987, finished in 2006, after which production was transferred to FAW and is currently equipped with Chinese cars.
3.5A-FHE - a version with a modified cylinder head, different camshafts, a slightly modified intake, a different exhaust manifold, the power increased to 120 hp. Was in production from 19891 to 1999 and was put on cars for the domestic Japanese market.

Malfunctions and their causes

The design of the motor repeats one-to-one the 4A motor, all those faults that are relevant for 4A also apply to 5A: problems with the distributor, with the lambda probe, with the engine temperature sensor, after which the internal combustion engine does not start, the revolutions are floating due to a dirty damper, an idle sensor course and so on. There are no hydraulic compensators for 5A, so every 100 thousand we carry out the valve adjustment procedure, after the same run we change the timing belt. In general, everything is standard for the A series, we look at the full list of engine diseases.

Toyota 5A-F / FE / FHE engine tuning

Chip tuning. Atmo. Turbo

Exactly as in the atmospheric version, the motor will not show anything supernatural. The only thing that makes sense is to bore the cylinders to a diameter of 81 mm, under the 4A-FE piston, thereby we get a working volume of 1.6 liters and, in fact, a 4A-FE engine, but there is a risk of running into casting defects. You can put a straight-through exhaust with a 4-2-1 spider, but this will not give anything serious.

Turbine on 5A-FE

Initially, this motor was developed for the most quiet movement, no sport was provided, so any serious tuning will entail the replacement of all regular junk, for tuning and for the turbine, this is very useful. The most reasonable option possible is to order a 4A-FE whale on a small turbine and put it on a standard piston, after having installed 360cc injectors, a 255 valbro pump and a direct-flow outlet on the 51st pipe, set it up on Abite. It will give it up to 140-150 hp, the resource will be greatly reduced. Want a resource, change the crankshaft, shp, cut the cylinder head ... or swap 4A-GE)).

Automotive giant Toyota in 1987 began work on the release of a new line of power units for passenger cars. She received the marking "5A". In this article, we will analyze the engine 5AFE. During the entire production period, which was 12 years, the power plant was produced in three types of modification.

They received the following names:

first generation - 5A-F;
second generation - 5A-FE;
third generation - 5A-FHE.

First generation

The power unit with the index 5A-F is distinguished by the presence of a gas distribution mechanism, the design of which provides for the installation of 4 valves per cylinder according to the DOHC scheme. In other words, the engine has two camshafts that move their valve bank.

This system allows one camshaft to move the intake valves and the other the exhaust valves. With the help of pushers, the valves are set in motion. Thanks to the DOHC system, the engines of the Toyota 5A range have high power ratings.

Second generation

The 5A-FE engine is an improved version of the 5A-FE. A major modification was made to the system responsible for the injection of the fuel mixture. The end result showed that an electronic fuel injection system was installed in the engine, called EFI - Electronic Fuel Injection.

Model	Body type	Release period	Manufacturing market
Carina	AT170	1990–1992	Japanese
Carina	AT192	1992–1996	Japanese
Carina	AT212	1996–2001	Japanese
Corolla	AE91	1989–1992	Japanese
Corolla	AE100	1991–2001	Japanese
Corolla	AE110	1995–2000	Japanese
Corolla ceres	AE100	1992–1998	Japanese
Corona	AT170	1989–1992	Japanese
Soluna	AL50	1996–2003	Asiatic
Sprinter	AE91	1989–1992	Japanese
Sprinter	AE100	1991–1995	Japanese
Sprinter	AE110	1995–2000	Japanese
Sprinter Marino	AE100	1992–1998	Japanese
Vios	AXP42	2002–2006	Chinese

Due to the high quality of construction, this motor is considered very successful. It is also well suited for renovation work. Finding spare parts for this power plant is not a problem. The release of cars of the joint Japanese-Chinese venture Toyota and Tianjin FAW Xiali, is produced with these power plants under the hood, to this day. They are used in small cars such as Vela and Weizhi.

How is the motor doing in Russia?

Most domestic Toyota vehicle owners, under the hood of which there is an engine modification called 5A-FE, leave positive ratings for the performance of the 5A-FE. They claim that the average engine resource is 300 thousand km. Further operation of the car is accompanied by an increase in the consumption of oily liquid. The valve stem seals should be replaced when the mileage is 200,000 km. Subsequent such operations must be carried out with a frequency of 100,000 km.

Many Toyota owners, whose powerplant is called the 5A-FE, have experienced the problem of thrust dips when driving at medium crankshaft speeds. This occurs when low-quality Russian fuel is used, or there are problems in the power supply and ignition systems.

Cons of the motor

The process of operating the 5A-FE power plants is not complete without the occurrence of disadvantages

Camshaft beds are prone to increased wear.
Fixed type piston pins.
Difficulty adjusting intake valve clearances.

Despite this, overhaul of this motor is rarely done.

If it is necessary to replace the motor unit, it is quite easy to purchase a contract 5A-FE engine. Most of them are in good condition and the price is reasonable.

It should be noted that Japanese contract engines were not operated in the Russian Federation. Japanese manufacturers are leaders in the speed with which vehicle model ranges are updated. This allows the dismantling companies to purchase vehicles. In which engines are installed with a fair supply of service life.

We bring to your attention a price-list for a contract engine (without mileage in the Russian Federation) 5AFE

Recently, on the roads of the Russian Federation, more and more often you can find cars of Japanese manufacturers, which hide 5A engines under the hood. Such engines are capable of delivering a lot of worries to their owners. In this regard, I would like to tell in more detail what problems may arise during the operation of these units and how to eliminate these problems.

Diagnostics and its parameters

These parameters include:

Oxygen sensor (lambda probe)

If it breaks down, error No. 21 "pops up" on the control unit. In addition, there is an increase in fuel consumption due to the lack of heating correction. Replacing it with a new one, which is very expensive, helps to solve the problem. It is not recommended to install a used one, since it is a large resource of operating time, which in the end will soon lead to a repetition of the situation.

temperature sensor

Its malfunction can lead to the impossibility of starting the engine on "hot" and increased fuel consumption.

Throttle position sensor, called TPS sensor

If it breaks down, error No. 41 is recorded on the control unit. The problems that this malfunction causes concern to a greater extent cars with automatic transmission, in which there is an incorrect gear shift. In cars with a manual gearbox, the engine starts to "choke" at high revs. Replacing the sensor should include its adjustment.

MAP sensor

The most reliable, but it also fails. In case of its malfunctions, the level of CO in the exhaust gases increases, a "black exhaust" appears and the candles are "seated".

Knock sensor

In case of problems with it, error No. 52 is recorded on the control unit. He manifests himself as a sluggish acceleration.

Injectors

With prolonged use, the needles and nozzles become coated with soot and resins. As a result, there is a decrease in the performance of the injectors, increased fuel consumption and a noticeable shaking of the engine. The solution to the problem is to install new ones or restore old ones (flushing and processing).

Spark plugs and ignition system

Such problems are the most common reason for the circulation of not only 5A engines, but also all other vehicles. A red coating forms on the candles, as a result of this, the formation of a spark does not occur. The engine starts to run intermittently, fuel consumption increases. Replacing or refurbishing will help solve this problem.

In addition to the above problems, 5A engines may have problems with the control unit, fuel filter, air filter, or any other malfunctions. Most importantly, remember that if something rattles, then you should not wait for it to fall apart, timely contacting the service will extend the service life of the car in general and the engine in particular. And also all this will cost you much less than, say, straightening and painting a car in Togliatti. Therefore, keep an eye on your car, and it will keep an eye on your wallet.

Engines 5A, 4A, 7A-FE
The most common and by far the most widely repaired Japanese engine is the (4,5,7) A-FE series. Even a novice mechanic, diagnostician is aware of possible problems with engines of this series. I will try to highlight (put together) the problems of these engines. There are few of them, but they cause a lot of trouble to their owners.

Date from scanner:

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

Sensors
Oxygen sensor -

Many owners turn to diagnostics due to increased fuel consumption. One of the reasons is a banal break in the heater in the oxygen sensor. The error is fixed by the control unit code number 21. The heater can be checked with a conventional tester on the sensor contacts (R- 14 Ohm)

Temperature sensor.
If the sensor does not work properly, the owner will face a lot of problems. If the measuring element of the sensor breaks down, the control unit replaces the sensor readings and fixes its value at 80 degrees and fixes error 22. The engine, in case of such a malfunction, will work in normal mode, but only while the engine is warm. Once the engine has cooled down, it will be problematic to start it without doping, due to the short opening time of the injectors. It is not uncommon for the resistance of the sensor to change chaotically when the engine is running on H.H. - the revolutions will float

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

Throttle position sensor

MAP absolute pressure sensor

This sensor is the most reliable ever installed on Japanese cars. Its reliability is simply amazing. But it also has a lot 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 violated.

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 piezoplate. In the event of a sensor malfunction, or a break in the wiring, at overgazings of more than 3.5-4 tons. The ECU registers an error 52. There is lethargy during acceleration. You can check the operability with an oscilloscope, or by measuring the resistance between the sensor terminal and the case (if there is resistance, the sensor needs to be replaced).

Crankshaft sensor
A crankshaft sensor is installed on the 7A series engines. A conventional inductive sensor, similar to the ABC sensor, is practically trouble-free in operation. But embarrassment also happens. With an interturn short circuit 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 t. Revolutions. A kind of cutoff, only at low revs. It is quite difficult to detect an interturn short circuit. The oscilloscope does not show a decrease in the amplitude of pulses or a change in frequency (with acceleration), and it is rather difficult to notice changes in Ohm fractions with a tester. If symptoms of speed limitation occur at 3-4 thousand, just replace the sensor with a known good one. In addition, a lot of trouble is caused by damage to the driving ring, which is damaged by careless mechanics when they replace the front crankshaft oil seal or timing belt. Having broken the teeth of the crown, and restoring them by welding, they achieve only a visible absence of damage. At the same time, the crankshaft position sensor ceases to adequately read information, the ignition timing begins to change chaotically, which leads to a loss of power, unstable engine operation and an increase in fuel consumption

Injectors (nozzles)

Idle valve, IACV

Ignition system. Candles.

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

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

« Subtle "faults
On modern engines 4A, 7A, the Japanese changed the firmware of the control unit (apparently for faster engine warm-up). The change lies in the fact that the engine reaches H.H. rpm only at a temperature of 85 degrees. The design of the engine cooling system has also been changed. Now the small cooling circle passes intensively through the block head (not through the branch pipe behind the engine, as it was before). Of course, the cooling of the head has become more efficient, and the engine as a whole has become more efficient. But in winter, with such cooling when driving, the engine temperature reaches a temperature of 75-80 degrees. And as a result, constant warming up revolutions (1100-1300), increased fuel consumption and nervousness of the owners. You can deal with this problem either by insulating the engine more strongly, or by changing the resistance of the temperature sensor (by deceiving the ECU).
Butter
Owners pour oil into the engine indiscriminately, without thinking about the consequences. Few people understand that different types of oils are not compatible and, when mixed, form an insoluble slurry (coke), which leads to the complete destruction of the engine.

Air filter
The most inexpensive and readily available element is the air filter. Owners very often forget about replacing it, without thinking about the likely increase in fuel consumption. Often, due to a clogged filter, the combustion chamber is very heavily contaminated with burned oil deposits, valves and candles are heavily contaminated. When diagnosing, it can be mistakenly assumed that the wear of the valve stem seals is to blame, but the root cause is a clogged air filter, which increases the vacuum in the intake manifold when contaminated. Of course, in this case, the caps will also have to be changed.

Fuel filter also deserves attention. If it is not replaced in time (15-20 thousand mileage), the pump starts to work with overload, the pressure drops, and as a result, it becomes necessary to replace the pump. The plastic parts of the pump impeller and non-return valve wear prematurely.

Pressure drops. It should be noted that the operation of the motor is possible at a pressure of up to 1.5 kg (with a standard 2.4-2.7 kg). At reduced pressure, there are constant lumbago in the intake manifold, the start is problematic (after). Draft is noticeably reduced. Check pressure correctly with a pressure gauge. (access to the filter is not difficult). In the field, you can use the "return filling test". If, when the engine is running, less than one liter flows out of the gasoline return hose in 30 seconds, it is possible to judge the reduced pressure. 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 sagged. You can measure the current on the diagnostic block

When using a modern tool, the process of replacing the filter takes no more than half an hour. Previously, it took a lot of time. Mechanics always hoped in case that they were lucky and the lower fitting did not rust. But it often did. I had to puzzle for a long time with which gas wrench to hook the rolled 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, the control units did not have serious enough problems during operation.

The blocks had to be repaired only because of the "hard polarity reversal". It is important to note that all outputs of the control unit are signed. It is easy to find on the board the required sensor terminal for checking, or for 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 owners "with hands" perform the belt replacement procedure on their own (although this is not correct, they cannot properly tighten the crankshaft pulley). The mechanics will make a quality replacement within two hours (maximum). If the belt breaks, the valves do not meet the piston and the engine will not be fatally destroyed. Everything is calculated to the smallest detail.

We tried to tell you about the most common problems on engines of this series. The engine is very simple and reliable, and subject to very tough operation on "water-iron gasoline" and dusty roads of our great and mighty Motherland and "avos" mentality of the owners. Having endured all the bullying, it continues to delight to this day with its reliable and stable work, having won the status of the best Japanese engine.

Successful repairs to all.

"Reliable Japanese Engines". Automotive Diagnostic Notes

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