High engine speed at idle

Idle speed is a specific mode of engine operation, due to which the minimum amount of fuel burns in the cylinders. At the same time, the car does not stall, but continues to move. The minimum amount of combustion fuel required to operate the engine may vary depending on the temperature and design features of the engine. A problem that car owners sometimes encounter is high engine idle speed. Is this deviation dangerous? Without a doubt! When the minimum fuel rate increases, the car will not only stall at idle or consume too much fuel in this mode, but also release more toxic exhaust gases. Therefore, the causes of such a malfunction, as well as methods of elimination, should be known to every car owner.

What is high engine speed

High revolutions can be defined as the engine working too hard, which is a deviation under idle conditions. In this situation, irregular fuel distribution occurs and the unit overheats. It is important that at the moment of startup, high speeds are not considered a breakdown. But after that they must fall.

High rpm can be determined in three ways:

look at the tachometer. If its readings at idle speed exceed 950 rpm, it’s time to be alarmed. Although lower indicators may also be a cause for concern: it all depends on the design features of the internal combustion engine; if other indicators are the norm, this will be indicated in the technical passport;
by ear (if the speed increases, the internal combustion engine begins to operate more noisily);
a car with an injector has a special indicator on the dashboard (“Check engine”), which will light up in case of deviation.

Tachometer shows engine speed

Replacing the Throttle Position Sensor on a VAZ 2110

Using a Phillips screwdriver, unscrew the two sensor mounting bolts, disconnect the block and remove the sensor.

If traces of rust or oxidation are found on the rod, which regulates the speed, it is necessary to clean it with penetrating lubricant.

Next, a new sensor is installed, the block is connected and the idle speed is checked.

Causes of high speed on the carburetor

Since the “engines” on the injector and on the carburetor are structurally different, the reasons for high speeds at idle conditions also differ. Despite the fact that today cars with carburetors have been discontinued, there are quite a large number of them on the roads. Therefore, the problem of high idle speed cannot be eliminated. And the reasons for it may be the following:

the ratio of fuel and air supplied to the carburetor is off, which is possible if it is repaired or configured incorrectly;
failure of the throttle valve, which may be accompanied by two circumstances: accumulation of soot; formation of a crack, chipping (a very unpleasant situation that entails its replacement);
failures in dosing of incoming fuel. This occurs if the needle valve is stuck;
perhaps the choke is open, which is diagnosed by the operation of the primary chamber damper;
A common cause is a burnt gasket on the cylinder head. You can verify such a breakdown by opening the radiator cap with the car running. White smoke coming out? That's right, the gasket is unusable.

Repairs are made easier by the absence of sophisticated electronics inherent in injection engines, since all the shortcomings are purely mechanical in nature.

Ignition system

Some car owners often overlook malfunctions in the functioning of the car's ignition system, which can cause an increase in speed. There are three reasons for this at this point:

candles are acting up;
high-voltage wires do not provide impulse passage;
Damage to the ignition distribution cover.

If these problems are identified, then in most cases, replacing the listed system components helps eliminate them.

Choosing an auto electrician - main features

Most problems with increased speed, increased fuel consumption, and unstable idling are solved by an electrician. This specialist finds problems in the electrical part of the car, diagnoses all components, and carries out repair work in the electrical part. You are unlikely to figure this out on your own; you will have to try hard to study the wiring diagram for all the parts of your car. And finding the location of all the sensors is often difficult, especially in a technologically complex modern car. So you need to entrust the work to an experienced craftsman.

When choosing an auto electrician, consider the following features:

official service - in most cases this will be the best solution, since here specialists work only with one specific brand of car and provide a guarantee of quality;
the equipment of the service station plays an important role in identifying potential problems in your car; you just need to make sure that the station is well equipped and has normal equipment;
experience of a specialist - pay attention to who exactly will service your car, the technician must be quite experienced, it is better to check reviews about him from different sources;
a good option is to choose an electrician by recommendation; if you do not use the services of an official station, the recommendations of your friends will help you find the optimal service;
It is worth starting cooperation with diagnostic services; diagnostics will show how competent the specialist is and whether there is any point in further cooperation with these specialists.

As you can see, there are several ways to check a person’s competence and make sure of his professionalism. If you decide to have your car serviced at an unverified station, be sure to be present during the repair and monitor every step of the technician. This is your right, it is quite possible to be present during repairs even in a garage station, where not a single master will like it. You can leave your car unattended either with the officials or with a trusted service that you have been working with for quite a long time. Keep this in mind the next time you need to go get your car repaired.

We also suggest watching a video about car diagnostics:

Reasons for high speed on the injector

On the injector, the reasons why the speed increases can be divided into:

related to electronic malfunctions;
associated with mechanical problems.

In the first case, the sensors or controllers are acting up. In case of malfunctions of this kind, it is best to seek the help of specialists.

Throttle valve

If the reason lies in the poor functioning of the throttle valve (in most cases, it becomes jammed), the following happens:

the volume of air entering the cylinders increases disproportionately;
The ECU will "demand" more fuel to balance the mixture.

As a result, the car will not only consume much more fuel than it should, but it may even fail due to constant “overload” at high idle speeds. Diagnostics of the damper and, depending on the diagnostic results, chemical cleaning or replacement will help resolve the problem.

Engine temperature sensor

This device is considered subject to frequent failures, since it is located in the epicenter of inevitable temperature changes. If it was noticed that with certain initial conditions everything is in order with the motor, but the sensor is “playing naughty”. To diagnose, you will have to delve into the wiring.

With the ignition on you need to:

take data on the resistance from contact “A” to ground (the exact correct value is 10 Ohm);
take data on the resistance from ground to terminal “B” (if less than 10 Ohms, you need to sound the alarm;
also take data on the voltage at terminal “B” in relation to ground (the exact correct value is 5V).

There may be a problem with the sensor itself. To determine this, you need to take the above resistance readings with the engine cooled down and warmed up. When working properly, the readings should not differ.

Engine temperature sensor

Air flow sensor

The oil film that envelops this device during vehicle operation eventually leads to malfunctions of the element that measures and sends a signal to the computer about the amount of incoming air (hot-wire anemometer). As a result, the ECU does not have access to reliable information about the amount of air, and the speed begins to float. But first of all, it is worth inspecting the air filter. Perhaps it is simply clogged and air is not flowing freely.

Intake manifold

High speeds may be associated with air suction. There can be two types of faults in this unit:

deformation of the intake manifold;
breakdowns or burnout of the gasket.

If the second case is not so catastrophic, then the first will most likely lead to a call to the services of a car service, since grinding may be required. Problems will be detected, including when the engine warms up.

Other reasons

Other common reasons may be the following:

jamming of the gas pedal, which is typical for both an injector engine and a carburetor engine;
On the injector, the IAC (idle air control) and TPS (throttle position) sensors may fail: if there is a suspicion that it is they who are “sinning,” you will need to check the contacts;
ECU failures, which are checked using special computer programs;
the generator does not supply the required current rate, so the motor will begin to accelerate in pursuit of the required voltage;
For cars with a turbocharger, high speeds at idle can be caused by its wear or depressurization of the rotor shaft gasket.

If you cannot confidently identify the cause of the increase in speed, it is more prudent to contact specialists (especially in the case of an injector).

Intake manifold with throttle valve

Which TPS sensor to choose for replacement

For stable and long-term operation of the sensor, we advise you not to buy too cheap analogues of questionable quality. The factory installed throttle position sensor was GM 2112-1148200 .

DPDZ /2110/ GM 2112-1148200 price from 300 rub.
DPDZ /2110/ PEKAR 2112-1148200 price from 200 rub.
TPDZ /2110/ StartVOLT VS-TP 0110 price from 200 rub.
TPDZ /2110/ HOFER HF 750260 price from 150 rub.
DPDZ /2110/ CJSC Account Mash 2112-1148200-05 price from 400 rub.
DPDZ /2110/ JSC RIKOR ELECTRONICS 2112-1148200 price from 300 rub.

Remedies

Having accurately determined the cause of the problem, you can begin to eliminate it, which in many cases is done by yourself:

If there is an excess of fuel supplied, you need to inspect the throttle valve. Depending on its condition, clean it or replace it with a new one;
if there is an excess of air, you need to examine the intake manifold for leaks and gaskets for leaks: bad gaskets will have to be replaced, and with deformations or damage to the manifold, it is better to contact a specialist;
with electronics it’s a little more complicated: the ECU will require “reflashing”, which is highly undesirable to do on your own; failed IAC and TPS will require replacement, which also applies to temperature and air flow sensors; When accurately diagnosing a problem with electronic contacts, soldering is necessary;
problems associated with a sharp increase in speed, as a rule, are rooted in jamming of the mechanisms that provide fuel supply. Since they are susceptible to blockages (this includes the operation of the needle valve; if there is a problem with the supply, it needs to be replaced or cleaned);
Short circuits or voltage surges are the first enemies of electronics. Therefore, a possible solution to the problem may be to repair the generator or ignition system;
If the reason lies in the jamming of the gas pedal, first of all check whether a foreign object has rolled under the pedal.

When installing new sensors (IAC), we must not forget to enter data into the “memory” of the ECU. Otherwise, the electronic brain simply won’t see them.

Which IAC sensor to choose for replacement?

2112.1148300-04 was installed on cars 2110-12 . If for some reason you cannot buy a factory one, you can install an analogue sensor from other manufacturers.

РХХ /2110-12/ engineer. (2112.1148300-04) factory (KZTA, Kaluga) price from 600 rub.
РХХ /2110-12/ engineer. FENOX SIP10100O7 price from 300 rub.
РХХ /2110-12/ engineer. HOFER HF 750381 price from 250 rub.
РХХ /2110-12/ engineer. MANOVER MR-2112-1148 price from 350 rub.
РХХ /2110-12/ engineer. StartVOLT VSM 0112 price from 450 rub.