The situation when the car stalls on a cold or the revs float immediately after start is familiar to many drivers. This condition is irritating and often indicates that there has been a failure in the engine control or fuel supply system. Cold launch. This is a mode in which the motor operates on an enriched mixture, and any deviation from the specified parameters can lead to a stop.
The problem can lie in both banal low-quality gasoline and serious malfunctions of electronics. If the car stalls on cold, but after warming up works normally, the range of probable causes is significantly narrowed. In this article, we will discuss in detail the main nodes that require verification.
It is important to understand that ignoring symptoms can lead to more expensive repairs. Sensors.Those who have not yet failed completely, can give incorrect readings at low temperatures. Letβs look at where to find the root of evil.
Unrecorded air suction
One of the most common reasons that the engine stalls on a cold one is the air sucking into the intake manifold. When the motor cools, the metal parts are compressed and microcracks in the pipes or gaskets may increase. Excess air, getting into the collector, impoverishes the mixture, and the ECU does not have time to adjust the composition of the fuel-air mixture.
Most often, the sealing rings of nozzles, the gasket of the intake manifold or the corrugated air filter suffer. Check the system for tightness can be with the help of a smoke generator or spraying suspicious places with a carburetor cleaner when the engine is running. If the velocity changes, you've found the leak site.
β οΈ Note: The use of an open fire to search for an air suction is strictly prohibited due to the risk of ignition of fuel vapors. Use only special aerosols or smoke machines.
It is also worth inspecting the hoses of vacuum amplifiers and valves. Rubber swells and cracks over time, especially in winter. Even a small crack can cause unstable work at idle.
- π Visually inspect all rubber pipes for cracks and cracks.
- π Listen to the characteristic hissing on the working engine.
- π Check the clamping on the inlet tract.
If after replacing the damaged elements, the problem disappeared, then the reason was precisely in depressurization. This is a common situation for cars with a mileage of more than 100 thousand kilometers.
Failures of sensors and electronics
Modern engine can not work without correct indications from the sensor. If the car stalls on a cold one, the first suspect is often a coolant temperature sensor (CTP). It is he who informs the control unit that the engine is cold and requires enrichment of the mixture.
If the TTZ sends the wrong signal that the engine is already warmed up, the ECU will not increase the injection time. As a result, the mixture will be too poor for cold start, and the engine will stall. It is also worth paying attention to air-flower (DMP) or absolute pressure sensor (DBP).
Pollution or malfunction of the DMPV leads to incorrect calculation of the amount of air. The control unit receives distorted data and prepares a mixture of incorrect proportions. Cleaning the sensor with a special tool sometimes helps, but more often a replacement is required.
Another important element is idler (RXX) or throttle with electric drive. Nagar, formed on the edges of the valve, prevents it from opening at the right angle to maintain the speed. Electronics try to compensate for this, but when there is a lot of pollution, the system fails.
| Component | Symptom of malfunction | Method of verification |
|---|---|---|
| JOHN | Poor mix on cold, no increase in turnover | Measurement of resistance by multimeter |
| DMRV | Floating speeds, increased consumption | Disabling chips, scanner diagnostics |
| RXX | Failed by gas discharge, unstable XX | Cleaning, checking the rod's progress |
Diagnosing electronic components requires a scanner. Error reading will help you quickly determine which sensor is giving out values that are outside the acceptable range.
Problems with the fuel system
If the engine stalls on cold, problems with fuel supply cannot be ruled out. Low pressure in the ramp or contaminated nozzles will not create the necessary concentration of the mixture to start. This is especially true in winter, when gasoline may contain condensate.
The fuel pump may lose productivity. If the gas pump net is clogged with dirt, the pressure in the system drops. The hot engine can still keep up, but on the cold, when maximum return is required, the pump cannot cope. It's worth checking out. fuel-filter.
βοΈ Diagnostics of the fuel system
The nozzles also need attention. If the sprayer is clogged or does not hold pressure (spray), the mixture will be disrupted. In the first case, there is little fuel, in the second - it fills candles. Cleaning the nozzles on the stand is an effective method of solving the problem.
β οΈ Before depressurizing the fuel ramp, be sure to relieve pressure in the system, otherwise gasoline may spray in your face with a fountain.
Fuel quality plays a key role. Bad gasoline with low octane or a large amount of impurities burns unstablely. Try to develop a tank and refuel at a proven gas station. Sometimes this solves the problem without interfering with the design of the car.
Ignition and candle system
A faint spark is another reason why the car stalls on the cold. At low temperatures, it is more difficult to break the candle gap, and if the ignition system has defects, ignition gaps are inevitable. First, check it out. spark-plug.
Coar on the electrodes, an increased gap or cracks in the insulator ceramics interfere with normal spark formation. It is also worth inspecting high-voltage wires and ignition coils. Microcracks in wire insulation can lead to breakdowns in the mass, especially in wet weather.
For cars with a ignition distributor (trumbler) it is important to check the lid and runner. Oxidation of contacts inside the lid or breakdown of the plastic itself often causes the engine to triple or stall.
How to check the ignition coil with a multimeter?
To check the primary winding, switch the multimeter to resistance measurement mode (200 ohms). Normal values are usually 0.4β2.0 ohms. For the secondary winding (mode 20 kΞ©), the values should be in the range of 2-4 kΞ©, but the exact figures depend on the model of the coil. If the resistance is infinite or equal to zero, the coil is faulty.
Don't forget the angle of the ignition. Although in modern cars it is regulated electronically, shifting the GRM tags or a malfunction of the crankshaft position sensor can lead to the fact that the spark will not come in time. This causes claps to the collector and stop the motor.
- π―οΈ Unwrapped candles and appreciate the color of the nagar (black is rich, white is poor).
- β‘ Check the coils for breaks in the dark.
- π Examine the wire tips for oxidation.
Mechanical problems of the engine
Sometimes the reason that the cold stops is in mechanics. Low. compression In cylinders, it does not allow to create enough pressure to ignite the mixture. This may be due to wear of piston rings, burn of valves or breakdown of the gasket of the GBC.
Gaps in the valve mechanism also affect the operation of the engine. If the heat gaps are not adjusted (on engines without hydraulic compensators), the valve may not fully close or open. On a cold engine, this is especially evident.
The gas distribution phases are another important parameter. If the belt or timing chain is stretched or installed with an error even on one tooth, the engine will work unstable. In such cases, power loss and increased fuel consumption are often observed.
Measure the compression on a cold and warm engine. If the hot compression increases, and the cold low compression - probably worn piston rings. If compression is low everywhere, the problem is in the valves.
Intake and exhaust valves may burn out. This leads to loss of tightness of the combustion chamber. The engine begins to triple, and at idle revs can stall due to the fact that part of the mixture simply flies into the exhaust system or back into the intake.
Features of winter operation
In winter, the list of reasons why it is cold is supplemented by specific factors. Frozen condensate in the fuel system or throttle can block the operation of the nodes. Water in gasoline at negative temperatures turns into ice jams.
The thickened engine oil creates a huge resistance when scrolling the starter. The engine barely spins, and if the battery is not new, it does not have enough strength to accelerate the crankshaft to the revs necessary to start. As a result, the mixture does not ignite.
Iceing of the air filter or snow entering the inlet is also possible. Water can freeze in the crankcase gas recirculation valve (CVG), causing air suction or, conversely, the creation of excessive pressure.
- βοΈ Use winter diesel fuel or an antelene for diesels.
- π Watch the battery charge and the condition of the terminals.
- 𧣠Cover the engine with a blanket or use a preheater.
The main cause of problems in winter is condensation in fuel and thickened oil. Prevention includes the use of high-quality liquids and storage of cars in the garage or under heating.
Diagnosis and elimination methods
To determine exactly why the engine is dead on the cold, a systematic approach is necessary. Start with computer diagnostics. The scanner will show errors on ignition passes, sensors and fuel corrections. It'll save time and money.
If there are no errors, go to visual inspection and measurement. Checking compression, fuel pressure and finding an air sucker are basic procedures. Donβt change the details at random, itβs a way to nowhere.
The table below shows the approximate actions depending on the symptoms:
| Symptoms. | Probable cause | Action. |
|---|---|---|
| It will go off immediately after launch. | RXX, air suction | Cleaning RXX, checking leakage |
| They float, then they die. | DMRV, JUST | Diagnostics of sensors, cleaning of throttle |
| Troit and deaf | Candles, coils, nozzles | Replacement of candles, checking sparks and nozzles |
Remember that timely maintenance of the car reduces the risk of such problems. Regular replacement of filters, candles and the use of high-quality fuels will prolong the life of your engine.
Why does the car stop cold only in winter?
In winter, the effect of low temperatures on the viscosity of the oil, the capacity of the battery and the presence of condensate. Metal parts are compressed, increasing the gaps in the seals, which provokes an air sucker that in the summer would not be critical.
Can I drive if the engine is dead on warm-up?
You can drive, but it is not recommended. The operation of the engine at unstable speeds leads to increased wear of the cylinder-piston group and catalyst. In addition, it is not safe, as the motor can stall in motion, turning off the brake and steering amplifiers.
How often should I clean the throttle?
It is recommended to clean the throttle every 30-50,000 kilometers of run. However, the frequency depends on the operating conditions and the quality of the oil (the crankcase ventilation system pollutes the valve).