Increased idle speed on a warm engine

Why does Lada Priora stall while driving when releasing gas?

With such a malfunction of the system, the following indications of its operation change: air and fuel consumption increases, its injection time changes, the idle speed control step increases to 75 units, the voltage at the terminals of electrical appliances changes.

A little about the reasons

The Lada Priora stalls while driving when releasing gas: the causes of this malfunction most often are a violation of the composition of the fuel mixture entering the car’s engine.

Having analyzed the methods of car owners of this car model to eliminate this malfunction, we can conclude that such a violation may be caused by improper operation of both the throttle system and some sensors and regulators. A complete diagnosis of the car at a car service center will help to identify the specific reason for the “floating” idle speed, although sometimes it is possible to find the source of the engine’s malfunction on your own. To do this, you need to sequentially disconnect or replace the following sensors and regulators with ones that are known to work correctly, removed from another vehicle.

So, let's figure out what to do first in case of such a malfunction.

Checking the operation of the throttle valve

Very often, the cause of idle “floating” is a malfunction of the throttle position sensor (TPS). The graphite track inside a standardly installed part wears out over time, so it is replaced with a sensor with a non-contact system. After replacement, you need to reset the sensor error. To do this, disconnect the terminals from the battery for 30 seconds or more.

It is also necessary to check the cleanliness and integrity of the pipe leading from the air filter to the throttle valve, and adjust the tension of the gas pedal cable going to it.

It is also possible that the gasket of the throttle assembly has become unusable or the assembly itself needs to be thoroughly cleaned (motor oil could have gotten into it) with special compounds for washing carburetors.

Changing the idle air control

Car service specialists admit that sometimes they have to spend a long time selecting a correctly working (despite the fact that it is new) idle air regulator to stabilize the idle speed of the engine. It is in this case that, before handing over your car for service, you should use an IAC regulator removed (temporarily) from a working car of the same brand.

It is advisable to replace the idle air regulator itself in conjunction with cleaning the vehicle's throttle system.

Replacing the mass air flow sensor

Determining the performance of this sensor (mass air flow sensor) is quite simple. You need to measure the voltage at its terminals with a multimeter with the engine off. It should be less than 1 volt. If it exceeds this value, then this sensor requires replacement.

Other reasons

In addition to the above malfunctions, Priora car owners resort to the following types of repairs to their car aimed at eliminating idle “floating”:

• replacing the knock sensor (DS) or crankshaft sensor;
• cleaning the speed sensor (DS), fuel grid or fuel filter;
• checking the integrity of the wires suitable for the sensors and the cleanliness of their terminals;
• adjusting fuel pressure or the operation of the vehicle's air intake system;
• increasing the power of the electric generator by adding another diode to its circuit;
• change the voltage regulator;
• adjust the correct operation of the absorber valve;
• check the carbon dioxide content in the fuel mixture and the correct functioning of the oxygen sensor (lambda), or turn it off programmatically;
• Reset the vehicle's electronic control unit (ECU). To do this, the battery is disconnected for a while, and then, after connecting it, the electronic system is “self-learning”;
• perform flashing of the car's electronic system.

In general, such a situation can arise even due to poor quality of the fuel being poured. In addition to changing the gas station, the fuel system may need to be cleaned.

The situation when the Lada Priora stalls while driving when releasing the gas can arise either for one of the above reasons or for a combination of them. Therefore, before purchasing new parts (to avoid unnecessary costs), it is recommended to diagnose the operation of the vehicle system at a car service center.

There is a special offer on our website. You can get a free consultation with our corporate lawyer by simply submitting your question in the form below.

The beginning of problems

If you unexpectedly discover that the idle speed in your car is floating, not only do you not need to panic, but generally be nervous. This nasty thing can occur both on cars with a carburetor engine and on models with an injection engine, and most importantly, sometimes even decent foreign cars, not to mention domestic models, do not avoid this fate.

The only difference is in the fuel injection system and, accordingly, in the methods of eliminating this trivial nuisance. But, since we decided to consider the problem from the point of view of modern Priora and/or Kalina, then we will have to evaluate the injection version of the engine with the so-called electronic fuel injection.

How it happens in reality

However, the situation can develop completely differently: sometimes these surges can just as suddenly disappear after a short warm-up of the engine, but it also happens the other way around - you’ve been driving for a long time, you stop at a traffic light, for example, and then pandemonium begins.

What's the matter

There may be several reasons for this disgusting and inappropriate behavior. We will list all possible situations when the idle speed fluctuates.

1. The electronic control unit of the car (on-board computer), called the “brains,” has “gone crazy.” Simply put, the system caught a glitch.
2. The throttle position sensor is broken.
3. The temperature sensor brazenly “lies”, showing that the engine has long warmed up and is ready for maximum load, which means it no longer requires increased fuel supply.
4. If there are increased idle speeds, then it is likely that the crankcase ventilation valve has closed.

Well, of course, we should also mention the carburetor. Basically, the idle speed fluctuates only on those cars on which some “skilled person” got into the carburetor itself (removed it, for example), and then just as “skillfully” put it back in place, knocking down the setting and tightening something not this way.

By the way, if we take diesel engines as an example, then everything could not be simpler and the reason for the floating speed is the jamming of the blades in the pump, which occurs due to primitive rust. That is, you remove the rust from the blades and the speed returns to normal.

Replacing the rear engine oil seal

How to behave and what to do

1. Check the speed adjustment screw and simply tighten it if necessary. This way you will close the hole through which the air escapes.
2. Using regular pliers, pinch the fuel pipes one by one. This way you can determine which one has a crack or even a hole.
3. Check the crankcase vent valve for opening/closing. It is quite possible that it also does not work stably.
4. Be sure to look at the operation of the throttle valve. If it doesn't open on time or doesn't close on time, then naturally the problem is here.
5. Finally, having not found a single violation in the first four points, you can be sure that the cause of the floating speed was the “lying” on-board computer, that is, the “brains” of the car and the error can be eliminated either by having a special tester on hand, or after all by visiting a repair shop, where the error will be removed.

Recommendations

In addition to the above, don’t be lazy and also check the spark plugs, the wires going to them and the distributor. This does not greatly affect the speed, but in total it can bring a positive result.

I heard that on many Priors the idle speed fluctuates when the car is warmed up. So I was ready for this.

) Not always, but sometimes they float, and it’s annoying... Especially if you also turn on the headlights, rear window heater and heater, then the swimming range becomes even greater (from about 800-1000). Maybe still a break-in, although I heard that after 10.

000 thousand mileage, this kind of garbage also happens... If anyone had or still has the same problems, or maybe someone knows what to do about it, write and we’ll discuss it.

Floating speed

In addition to slowly falling revs, car enthusiasts may encounter a phenomenon called floating revs, when they drop and then rise sharply. The reason is excessive air supply into the system, which causes the engine to spin up to 2 thousand revolutions at idle.

This often happens in cars that have a fuel injection sensor. It calculates how much air the mixture needs. When its operation is disrupted, different amounts of oxygen are supplied at different times, as a result, speed jumps are observed approximately every 3 seconds.

Faced with a similar phenomenon, the same computer diagnostics will be a prerequisite

It is very important that this and all subsequent work is carried out by experienced, qualified specialists. By contacting a service that does not specialize in breakdowns of this kind, you may be faced with the need to carry out expensive engine overhauls ahead of time.

Today, when starting from a stop, I let off the gas and the revolutions do not fall, and sometimes even rise to 3 thousand. After a few seconds everything returns to normal. I suspect either the idle air control valve or the throttle position sensor. How to find out what exactly?

Comments 25

I have the same. I'm already so angry that today I posted an advertisement for sale. really fucked up .suka.

At traffic lights it stopped, the rpm was 1200 or 1000. Sometimes when you accelerated, they would drop, but not always. Turned it off, started it, everything is fine.

I changed the IAC and it lasted for three days. suka. I cleaned the DZ and IAC with carb cleaner. At the same time I changed the TPS.

Result: three days later the same thing happens again. However, today the revolutions themselves dropped several times to 840-880-920 or something.

Error 0507 (high XX) and error 0422 (Converter not effective) occurred

ZAEBALA ONA SUKA MENYA. PRODAU.

Buy a dpdz, it costs around 250 rubles, and rxx 400. It was the same. First I bought a phx, it didn’t help, I cleaned the throttle and it didn’t help. I changed the DPZ, now I drive normal) on mine the mileage is 65k 2008

The VAZ Priora (2170) slows down its speed poorly. Hi all. On my Priore, the speed does not drop when switching and can even rise on its own and hold on for a long time, 10 seconds or more. If you gas, it throws off. I cleaned the throttle - didn't help, changed the IAC - didn't help, changed the throttle valve regulator didn't help either. I tried to remove the chip from the air flow and start it, but the revolutions did not rise to 1600 as in theory they should. I sit and think what else could happen.

• The speed rises on a warm VAZ Priora engine - 13 answers
• No charging at idle - 4 answers
• Engine shutdown at idle, VAZ Priora – 3 answers
• The VAZ Priora engine is shaking at idle speed - 2 answers
• The car does not respond to gas, VAZ Priora – 2 answers

I suffered for 3 months with the same problem - on a warm engine the revolutions increased to 2000 and held for 5-10 seconds, tinkered with the guys, changed the throttle, IAC, temperature sensors, changed spark plugs, tinkered with the ignition - it didn’t help, I went to the service center a couple of times but since the “check” did not light up, there are no errors and even if it cracks. And then the other day I went to check the fluid level in the power steering barrel, everything was ok there, my gaze fell on the intake manifold on which some kind of lump was hanging on the back side (from the cabin side). I look exactly at the place where the hoses are placed under the air conditioner and there are plugs. One itself fell off somewhere and there were scraps left, the second stood in place, but I took it off - it was oak and burst along the length. I changed it while the engine was running - the increase in speed stopped, but it stopped starting. After that, I took them off, started them, and it floats. I removed the battery terminals for about 3 hours, installed the plugs, connected the terminals, everything worked and no longer floats!

Recommendations

Comments 32

The guys will laugh, but the fact is the fact, I have the same thing! Observation: there was no such problem until I installed a grid (blades) similar to that of the creator of the topic!

No, exactly, the fuel consumption on the highway is 6.0 - 6.3, I drive long distances at 120-140 km per hour, the temperature sensor was also changed to a new one half a year ago. I thought about it too, most likely I’ll buy a new one to check, thanks)))

The temperature sensor may be faulty, hence the ECU reads the readings incorrectly and slowly lowers the speed. Consumption should increase, haven’t you noticed?

It looks like this is the firmware, maybe it was already flashed by someone? The speed there is fixed based on temperature.

I adjusted the firmware myself to set the speed I wanted at any engine temperature.

Class. I want that too. What do you need to have for this?

You don't need to know much. Open the firmware file on your computer, for example in the Chiptuning program, configure what you need, and then upload the saved firmware to your brain. I have Bosch 7.9.7+

yes you need to solder to flash it

It’s clear, I know how to solder, but I’m afraid I’ll have to buy new ones later))) I’d rather pay the master 2.5 thousand)))

Here, as they say, the master is the gentleman. I actually tried different firmware and in the end I liked the stock Priora B174DT07 (Euro-4)

wow, cool, but do you have 2 oxygen sensors?

yes, the stock firmware was Euro 3

This happens to everyone even on staff to warm up the engine

no, not everyone is wrong, the revolutions should gradually drop when warming up, but for me they normalize when fully warmed up to 90 only, this is not correct))

It’s good in winter, it heats up quickly, it’s built into the firmware, but if there’s air leaks, then the revs will be low and it’ll stall.

oh exactly, thank you))) in winter, yes, but in summer it’s very unpleasant when the idle speed is higher than normal, it’s annoying because there’s no smoothness and when changing gears the car jerks as if I’m behind the wheel for the first time in my life, and in winter I’ll skid everywhere) ))

Read more: Replacing handbrake cables for Skoda Octavia A5

It's installed in the firmware, and it's the same for me.

Why does Lada Priora stall while driving when releasing gas?

With such a malfunction of the system, the following indications of its operation change: air and fuel consumption increases, its injection time changes, the idle speed control step increases to 75 units, the voltage at the terminals of electrical appliances changes.

A little about the reasons

The Lada Priora stalls while driving when releasing gas: the causes of this malfunction most often are a violation of the composition of the fuel mixture entering the car’s engine.

Having analyzed the methods of car owners of this car model to eliminate this malfunction, we can conclude that such a violation may be caused by improper operation of both the throttle system and some sensors and regulators. A complete diagnosis of the car at a car service center will help to identify the specific reason for the “floating” idle speed, although sometimes it is possible to find the source of the engine’s malfunction on your own. To do this, you need to sequentially disconnect or replace the following sensors and regulators with ones that are known to work correctly, removed from another vehicle.

So, let's figure out what to do first in case of such a malfunction.

Checking the operation of the throttle valve

Very often, the cause of idle “floating” is a malfunction of the throttle position sensor (TPS). The graphite track inside a standardly installed part wears out over time, so it is replaced with a sensor with a non-contact system. After replacement, you need to reset the sensor error. To do this, disconnect the terminals from the battery for 30 seconds or more.

It is also necessary to check the cleanliness and integrity of the pipe leading from the air filter to the throttle valve, and adjust the tension of the gas pedal cable going to it.

It is also possible that the gasket of the throttle assembly has become unusable or the assembly itself needs to be thoroughly cleaned (motor oil could have gotten into it) with special compounds for washing carburetors.

Changing the idle air control

Car service specialists admit that sometimes they have to spend a long time selecting a correctly working (despite the fact that it is new) idle air regulator to stabilize the idle speed of the engine. It is in this case that, before handing over your car for service, you should use an IAC regulator removed (temporarily) from a working car of the same brand.

It is advisable to replace the idle air regulator itself in conjunction with cleaning the vehicle's throttle system.

Replacing the mass air flow sensor

Determining the performance of this sensor (mass air flow sensor) is quite simple. You need to measure the voltage at its terminals with a multimeter with the engine off. It should be less than 1 volt. If it exceeds this value, then this sensor requires replacement.

Other reasons

In addition to the above malfunctions, Priora car owners resort to the following types of repairs to their car aimed at eliminating idle “floating”:

• replacing the knock sensor (DS) or crankshaft sensor;
• cleaning the speed sensor (DS), fuel grid or fuel filter;
• checking the integrity of the wires suitable for the sensors and the cleanliness of their terminals;
• adjusting fuel pressure or the operation of the vehicle's air intake system;
• increasing the power of the electric generator by adding another diode to its circuit;
• change the voltage regulator;
• adjust the correct operation of the absorber valve;
• check the carbon dioxide content in the fuel mixture and the correct functioning of the oxygen sensor (lambda), or turn it off programmatically;
• Reset the vehicle's electronic control unit (ECU). To do this, the battery is disconnected for a while, and then, after connecting it, the electronic system is “self-learning”;
• perform flashing of the car's electronic system.

In general, such a situation can arise even due to poor quality of the fuel being poured. In addition to changing the gas station, the fuel system may need to be cleaned.

The situation when the Lada Priora stalls while driving when releasing the gas can arise either for one of the above reasons or for a combination of them. Therefore, before purchasing new parts (to avoid unnecessary costs), it is recommended to diagnose the operation of the vehicle system at a car service center.

There is a special offer on our website. You can get a free consultation with our corporate lawyer by simply submitting your question in the form below.

Spontaneous increase in speed: we understand the reasons

Increasing engine speed while driving without the driver pressing the accelerator pedal can lead to an emergency situation, increased fuel consumption, and an arbitrary increase in the speed limit. If such a situation arises, the driver must take measures to eliminate it. Let's look at the possible reasons.

1. Accelerator pedal cable sticking

. The cable in the system for transmitting the position of the gas pedal to the throttle valve was used mainly in cars before the year 2000. During the operation of the car, the metal strands of the cable gradually wear out and break. The cable loses its geometric integrity and becomes frayed. As a result, the force of the return spring is not enough to close the throttle valve when the accelerator pedal is released, and the speed remains elevated. The repair consists of replacing the cable.

2. Wear of potentiometers (rheostats, variable resistors) in the accelerator pedal sensor.

Resistors have a limited service life, their working surface wears off. In this case, violations of the resistance parameters are possible, which can lead to either an arbitrary increase or decrease in the engine speed. The parameters of the potentiometers are controlled using a multimeter.

3. Air filter clogged.

Failure to promptly replace the air filter leads to an increase in the fuel/air ratio, and as a result, an increase in crankshaft speed. To check the air filter's capacity, it can be temporarily removed.

4. Malfunction of the idle air control.

Failure of the regulator can lead to jamming of the throttle valve, changing the size of the bypass (bypass) channel, which leads to an arbitrary increase in speed. The malfunction can be eliminated by cleaning with carburetor cleaner.

5. The electric throttle actuator is stuck.

This problem can occur if the air filter is very worn. It needs to be replaced and the damper mechanism washed.

6. Clogged jets in carburetor engines.

Carburetors in the intake systems of power units are currently installed on special equipment. If the jets become clogged or waste oil gets into the carburetor, the crankshaft rotation speed may change. Repairs are carried out by cleaning with special means and purging the jets.

7. Worn injectors.

When using low-quality fuel, accelerated wear of the injectors is possible. At the same time, a poor-quality combustion torch is formed and the speed increases. Injectors are checked on a special stand.

8. Timing belt (chain) stretching.

This leads to a change in the ignition angle, “floating” speed. The belt (or chain) needs to be changed.

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.

How to stabilize floating speed

1. Penetration of foreign air into the engine. It is necessary to check the tightness of the air system channels with the intake manifold. For such purposes, it is necessary to dismantle each hose separately and pump it with a pump or compressor, but you can try spraying liquid -40 on the hoses, where it will quickly evaporate; there is most likely a crack in the hose. In such a situation, it is better to replace the damaged hose with a new one rather than wrap it with electrical tape.
2. Replacement of IAC. The condition of this device is checked with a conventional multimeter, which needs to check its resistance. If the resistance readings are in the range of 40-80 Ohms, the regulator is faulty and such a device requires immediate replacement.
3. Cleaning the valve and elements of the engine ventilation system. In this case, you will have to disassemble the oil sump and get to the ventilation valve. It should be pulled out and washed in a product for cleaning engine elements from an oil film. You can use regular kerosene. Next, dry the valve thoroughly and then put it in its place.
4. Replacing the air flow sensor. This is the most delicate part and most often cannot be repaired. Therefore, if the cause is the air flow sensor, then it is advisable to replace it. It is known from practice that even professionals cannot repair a hot-wire anemometer.
5. Flushing the throttle valve and then installing it in the correct position. There are two methods for cleaning the throttle valve from oil contaminants: without removing it from the car, and also with removing the throttle valve. When removing the damper from the car, you must disconnect all wires and hoses from the damper, loosen it and pull it out. Next, place it in a container and fill it with cleaning aerosol. If the oil stains on the surface of the throttle valve are already old, you can clean them with a brush. Next, dry the damper surfaces with a rag and put them in place, connecting all the wires and hoses. If the damper is not removed from the car, then it can be washed on a hot power unit with a similar aerosol. Before spraying cleaning agent, disconnect power from the throttle valve. First you need to pour the product inside the throttle valve, wait a few minutes and start the engine. With the power unit operating, continue cleaning the damper with the same product. If, during such cleaning, white smoke comes from the damper, then this is normal, since oil contaminants are cleaned in this way. At the end of the work, you should connect the wires and adjust the operating order of the throttle valve on the computer, setting the required opening gap.
6. Idle speed adjustment. This procedure can be carried out using a regular screwdriver, adjusting the screws for the quality of the fuel mixture and the number of engine revolutions.
7. Replacing the solenoid valve. If the carburetor idle valve malfunctions, the engine can only operate when the choke handle is pulled out. Therefore, in order to prevent idle speed fluctuations, it is advisable to replace the valve with a known good one or a new one.
8. Cleaning the idle air jet. Even in the old days, cleaning the jet from oil deposits was considered a very labor-intensive task. Currently there is no need to remove the jet from the carburetor. To do this, you just need to pour a specialized product into it, designed for cleaning carburetors, and wait in this state for several minutes. Then you need to clean the nozzle from dirt using compressed air.
9. Treatment of parts of the fuel pump on a diesel engine from rust. To perform this task, you will need a specialized corrosion cleaning agent. This can be either an imported or a domestic product. It is simply sprayed into the fuel tank by opening its neck before refueling with diesel fuel at a gas station. The cleaning agent will clean the pump parts from rust on its own. In order to prevent similar corrosion of the high-pressure pump in the future, it is recommended to pour a glass of motor oil into the tank, which can form a protective film on the surface of the pump parts when moving.

We recommend: Non-contact ignition system (BSI)

You need to know that if uneven engine speed occurs at idle, you must immediately contact a service station and carry out detailed diagnostics of the operation of all engine systems. Timely detection of faults will protect you from costly repairs.

Conclusion

Many car enthusiasts do not know the reasons for the appearance of the effect of high idle speeds, and especially the methods for eliminating them. So, naturally, experts and car mechanics advise contacting a car service right away, but our man, until he tries it himself, don’t slow down.

There are many reasons for the appearance of the effect of high speed, from faulty sensors to an error in the electrical control unit. You can also fix the problem at home, which is what owners of VAZs and other Russian cars do. But owners of foreign cars will have to contact a car service center, where repairs can cost a large amount.

Source: avtodvigateli.com

The engine runs erratically or stalls at idle Lada Priora

Video on the topic “Lada Priora. The engine runs erratically or stalls at idle.”

Unstable idle on Priora, what is the reason

Priora's revs float - one of the solutions

idle speed disappears. stalls at traffic lights. in neutral. cause found

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 revs on the Priora fluctuate, such reproaches can be heard quite often in the direction of the power unit of this brand of VAZ car. And, although, according to many experts, the engine in the Priora is, in general, quite reliable, the car itself, in the language of professionals, is very “raw”, and, by and large, requires various technical modifications and improvements. After all, why should our domestic automotive industry (passenger cars, at least) constantly trail behind foreign manufacturers?

Scrolling through information automobile portals, you constantly come across various complaints from car enthusiasts, like, I bought a Priora car, but the revs are floating, the car is new, I don’t know what to do, please advise. I contacted the service center and they answered that there was nothing wrong with this, that many cars have this defect, so be patient, well, if you really don’t have enough patience, then you had to buy an imported car, not just from a reputable company , but also, naturally, in a different price segment.

According to experienced motorists, the instability of the engine speed (the speed floats) of a Priora car can be caused by various reasons, here, as they say, someone will be “lucky”. Such reasons include poor performance of the idle speed sensor or magnetic valve. In this case, the engine will not operate stably in IAC; starting it will become very difficult, especially when cold, and it may suddenly begin to stall. We generally do not mention such “joy” as an increase in fuel consumption.

By the way, you should also pay attention to the quality of the fuel used; sometimes the floating speed of the Priora engine can be caused by this very reason

In some Priora cars, the engine of which was working perfectly well, the Priora's speed begins to float as soon as the power unit receives additional load, in the form of the headlights, interior heater, or air conditioning being on

In this case, you should pay attention to the generator. Well, an extremely radical measure is to “reflash” the system, but this should only be done on a working car, after carrying out its full diagnostics, and in the appropriate specialized service, otherwise, instead of solving problems, you can easily acquire additional

When the speed started to fluctuate, I changed the spark plugs and the idle speed sensor, but it didn’t help.

I also have the same problem, but I think it’s the spark plugs, the coil is causing some kind of malfunction 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