Your own diagnostician: why the engine speed fluctuates on a Priora - a theoretical basis
- failure of the mass air flow sensor (MAF);
- failure of the throttle position sensor (TPS);
- air leak;
- defective idle air controller (IAC).
What the engine will do in this state of affairs is to raise the speed of the power plant, while the volume of injected gasoline will remain the same. This means that the mixture will become leaner and the engine will begin to stall smoothly.
As the crankshaft speed decreases, the amount of air will decrease. After reaching a critical point, at which the injection volume of high-octane liquid is sufficient to obtain a combustible mixture of normal quality, engine operation stabilizes again. This process is called “floating revolutions”. It is closed and will be repeated until the causes are clarified and measures are taken to eliminate them.
We determine the malfunction ourselves
The regulator is designed to maintain idle speed within a specified range and ensure proper and timely warming up of the engine.
Although engine failures in this mode are rare on the Lada Kalina, practice has made it possible to establish a certain set of signals indicating a malfunction of the regulator.
- When the unit begins to heat up at low outside temperatures, the number of revolutions cannot exceed the threshold value of 1500 per minute, which “delays” the time to reach operating temperature.
- difficulty starting the unit;
- while the gearbox is in neutral, a floating engine speed is observed;
- when the transmission phases change while in motion, the engine spontaneously stops;
Attentive owners of Lada Kalina testify to a decrease in speed after turning on the air conditioning compressor. This often causes the engine to stop and the lubricant pressure symbol on the tiller to illuminate.
The most common malfunction is instability of the speed. When driving above the 50,000 mile mark and such symptoms occur, it is recommended that you first clean the throttle body. Only then will it be possible to replace the controller. This device cannot be repaired, so this action has no alternative.
Replacing the sensor is not difficult and allows you to do it as quickly as possible, the main thing is to know where it is.
Important: checking sensors
The answer to the question why the idle speed on a Priora fluctuates can often be this: one of the three sensors (IAC, TPS, MAF) is faulty. It's quite easy to check:
- Start the power plant.
- Disconnect the IAC power supply and analyze: the IAC frequency remains the same or the motor stalls - the sensor needs to be replaced. If the frequency has increased, the sensor is working.
- Restore power to the regulator.
- Remove the chip from the mass air flow sensor and observe: the speed has increased - the mass air flow sensor is working; the engine has stalled - the mass air flow sensor should be replaced.
- Connect power to the TPS.
- Disconnect the block from the mass air flow sensor and analyze: the crankshaft rotation speed has increased - the mass air flow sensor is working, the engine stalls - the throttle position sensor is faulty.
- Attach the chip to the mass air flow sensor.
For your information. Often the problem is caused by a poor connection of the terminals of both the “negative” and “positive” wires.
Route map for eliminating unstable XX on a VAZ 2170
Unstable idle is caused by the fact that the computer incorrectly perceives or does not know at all the amount of air sucked into the intake manifold. A typical treatment recipe looks like this:
- Check the sensors (IAC, DFID, TPS) and replace the faulty ones.
- Make sure that the adsorber valve is in good condition.
- If, after cleaning the throttle valve on the VAZ 21126 engine, the speed fluctuates, you need to make sure that there is no air leakage through the connections to the pipes.
- Check whether the diaphragm in the vacuum brake booster is intact.
The reliable carburetor engine control circuit has long been supplanted by flexible electronics. The latter consists of a control unit and sensors operating according to a specific program. This trend has made it possible to achieve an increase in power and a decrease in fuel consumption. However, with the advent of electronics, the control system has become more vulnerable to malfunctions.
Replacement
Replacement requires only a small screwdriver.
- We turn off the minus sign in the battery, since the work will be done with the electrical equipment of the car.
- Remove the connector from the sensor.
Unscrew the two screws that secure the sensor to the housing and remove the sensor.
- We install the new sensor in the reverse order, not forgetting to install the O-ring.
If after replacement the problem is not solved, you need to clean the throttle valve; how to do this, read below.
Your own diagnostician: why the engine speed fluctuates on a Priora - a theoretical basis
- failure of the mass air flow sensor (MAF);
- failure of the throttle position sensor (TPS);
- air leak;
- defective idle air controller (IAC).
What the engine will do in this state of affairs is to raise the speed of the power plant, while the volume of injected gasoline will remain the same. This means that the mixture will become leaner and the engine will begin to stall smoothly.
As the crankshaft speed decreases, the amount of air will decrease. After reaching a critical point, at which the injection volume of high-octane liquid is sufficient to obtain a combustible mixture of normal quality, engine operation stabilizes again. This process is called “floating revolutions”. It is closed and will be repeated until the causes are clarified and measures are taken to eliminate them.
Advantages and disadvantages of an electronic pedal
Over the 7 years of operation of the Lada Priora with an electronic throttle control system, car enthusiasts have compiled pronounced pros and cons of operating a car with e-gas.
Advantages:
- Reduced fuel consumption. If you press the gas too hard, the ECU will correct this moment and prevent either overspeeding or increased fuel consumption. “Over-gassing” will not work;
- Environmental friendliness. The introduction of this system took place under the influence of the popular movement of automakers who bring their cars to European standards. Priora is Euro 4 compliant;
- Instant response of the car to pressing the accelerator lever (only if the system is working properly).
Important: checking sensors
The answer to the question why the idle speed on a Priora fluctuates can often be this: one of the three sensors (IAC, TPS, MAF) is faulty. It's quite easy to check:
- Start the power plant.
- Disconnect the IAC power supply and analyze: the IAC frequency remains the same or the motor stalls - the sensor needs to be replaced. If the frequency has increased, the sensor is working.
- Restore power to the regulator.
- Remove the chip from the mass air flow sensor and observe: the speed has increased - the mass air flow sensor is working; the engine has stalled - the mass air flow sensor should be replaced.
- Connect power to the TPS.
- Disconnect the block from the mass air flow sensor and analyze: the crankshaft rotation speed has increased - the mass air flow sensor is working, the engine stalls - the throttle position sensor is faulty.
- Attach the chip to the mass air flow sensor.
For your information. Often the problem is caused by a poor connection of the terminals of both the “negative” and “positive” wires.
Route map for eliminating unstable XX on a VAZ 2170
Unstable idle is caused by the fact that the computer incorrectly perceives or does not know at all the amount of air sucked into the intake manifold. A typical treatment recipe looks like this:
- Check the sensors (IAC, DFID, TPS) and replace the faulty ones.
- Make sure that the adsorber valve is in good condition.
- If, after cleaning the throttle valve on the VAZ 21126 engine, the speed fluctuates, you need to make sure that there is no air leakage through the connections to the pipes.
- Check whether the diaphragm in the vacuum brake booster is intact.
When the speed started to fluctuate, I changed the spark plugs and the idle speed sensor, but it didn’t help.
Comments 25
I also have the same problem. But I think it’s the spark plugs, the coil is causing some kind of failure or the filters (air, fuel) Or am I wrong, this can’t be the case?
Good evening everyone. I have a 2010 Priora 1.6 16 valve. The revs fluctuated and stalled. No diagnostics showed anything ((thought I could fix it myself
