Почему машина набирает обороты на холостом ходу: Высокие обороты двигателя на холостом ходу: причины, способы решения

Почему на холодном двигателе высокие обороты. 7 главных причин повышенных оборотов хх на холодную

Высокие обороты на холодную могут появиться как в штатном режиме работы двигателя, так и при выходе из строя некоторых его датчиков. В последнем случае на инжекторных двигателях необходимо выполнить проверку регулятора холостого хода, датчика положения дроссельной заслонки, датчика температуры охлаждающей жидкости, впускного коллектора. У карбюраторных бензиновых двигателей также нужно проверить регулировку холостого хода, работу воздушной заслонки, камеры карбюратора.

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Работа ДВС на прогревочных оборотах

В общем случае высокие обороты на холодном двигателе в холодную погоду — явление нормальное. Однако их значение и продолжительность работы мотора в таком режиме может быть разным. Так, если запустить двигатель при температуре, например, от +20°С и выше, то время, когда значение оборотов холостого хода вернется к указанному в мануале (приблизительно 600…800 оборотов в минуту) составит несколько секунд (2…5 секунд в летнее время и около 5…10 секунд в зимнее). Если этого не происходит — значит, есть поломка, и необходимо выполнять дополнительную проверку и соответствующие ремонтные меры.

Что касается запуска бензинового двигателя на холодную при температуре, например, –10°С, то высокие прогревочные обороты будут приблизительно в два раза превышать указанные производителем обороты холостого хода. Соответственно, чем ниже будет температура — тем время возвращения к нормальным холостым оборотам будет выше.

Высокие обороты при запуске двигателя на холодную необходимо по двум причинам. Первая — постепенный прогрев моторного масла, и соответственно, уменьшения его вязкости. Вторая — постепенный нагрев двигателя до нормальной рабочей температуры охлаждающей жидкости, составляющей около +80°С…+90°С. Это достигается увеличением количества сжигаемого топлива.

Поэтому, появление больших оборотов при запуске двигателя на холодную — нормальное явление. Однако необходимо учитывать их значение и время, через которые они возвращаются к значению, соответствующему холостому ходу. Значения оборотов и времени указываются в технической документации к конкретному автомобилю. Если обороты и/или время возвращения увеличены — значит, необходимо искать причину поломки.

Причина высоких оборотов двигателя на холостом ходу

Выделяют аж четырнадцать причин, почему на холодном двигателе большие обороты длительное время после запуска. В частности:

1. Дроссельная заслонка. Воздух может попадать в двигатель через приподнятую дроссельную заслонку, когда, например, тросик ее привода перетянут (если он предусмотрен конструкцией). В этом случае на холостом ходу в двигатель попадает больше чем необходимо количество воздуха, что, собственно, и приводит к тому, что при холодном запуске высокие обороты.
   Еще один вариант — использование жесткого коврика на полу, который может подпирать педаль газа при том, что водитель не нажимает на нее. В этом случае обороты также будут повышенными, причем не только при холодном, но и при прогретом моторе.
   Дроссельная заслонка может полностью не закрываться по причине того, что она очень сильно загрязнена нагаром. В этом случае он попросту не даст ей плотно прилегать.
2. Канал холостого хода. У всех карбюраторных моделей двигателей конструкция предусматривает наличие воздушного канала в обход дроссельной заслонки. Сечение канала регулируется специальным регулировочным болтом. Соответственно, при неправильной настройке сечения канала через канал холостого хода будет проходить большее чем необходимо количество воздуха, что и приведет к тому, что на холодную большие обороты двигателя. Правда, подобная ситуация может быть и «на горячую».
3. Воздушный канал для поддержания высоких оборотов холодного двигателя. Этот канал перекрывается при помощи штока или заслонки. Соответственно, положение штока или угол наклона заслонки зависит от температуры антифриза в системе охлаждения (то есть, по сути, температуры двигателя).
   При холодном двигателе канал полностью открыт, и соответственно, через него поступает большое количество воздуха, обеспечивая повышенные обороты на холодную. По мере прогревания двигателя канал перекрывается. Если шток или заслонка не полностью перекрывают поступление дополнительной порции воздуха, то это и приведет к повышенным оборотам двигателя.
4. Воздушный канал впускного коллектора. В разных конструкциях двигателей он перекрывается серводвигателем, импульсным электродвигателем, электромагнитным клапаном либо соленоидом с импульсным управлением. При выходе из строя указанных элементов воздушный канал не будет перекрыт должным образом, и соответственно, через него будет проходить большое количество воздуха во впускной коллектор.
5. Трубки впускного коллектора. Зачастую лишний воздух в систему поступает по причине разгерметизации патрубков либо мест их присоединения. Обычно это можно определить по исходящему оттуда свисту.
6. У некоторых автомобилей, например «Тойота», конструкция двигателя предусматривает использование электродвигателей принудительного повышения оборотов холостого хода. Их модели и методы управления различаются, однако все имеют отдельную систему управления. Поэтому проблема высоких оборотов на холостом ходу может быть связана либо с указанным электродвигателем, либо с системой его управления.
7. Датчик положения дроссельной заслонки (ДПДЗ или TPS). Они бывают четырех видов, однако их основная задача передавать на блок управления двигателем информацию о том, в каком положении в конкретный момент времени находится заслонка. Соответственно, при неисправности ДПДЗ ЭБУ переходит в аварийный режим и дает команду на подачу максимального количества воздуха. Это приводит к образованию обедненной топливовоздушной смеси, а также высоким оборотам двигателя на холостом ходу. Зачастую при этом в режиме работы обороты могут «плавать». Обороты могут повышаться и при сбросе настроек работы дросселя.
8. Регулятор холостого хода. Эти устройства бывают трех типов — соленоидные, шаговые и роторные. Обычно причинами неисправности РХХ является повреждение его направляющей иглы либо повреждение его электрических контактов.
9. Датчик массового расхода воздуха (ДМРВ). При частичном или полном выходе из строя этого элемента на блок управления также будет подаваться некорректная информация о количестве подаваемого в двигатель воздуха. Соответственно, возможно возникновение ситуации, когда ЭБУ примет решение о большем или полном открытии дроссельной заслонки для увеличения поступления воздуха. Это естественным образом приведет к увеличению оборотов двигателя. При нестабильной работе ДМРВ обороты могут не только быть повышенными «на холодную», но и быть нестабильными при других режимах работы мотора.
10. Датчик температуры всасываемого воздуха (ДТВВ, или IAT). Ситуация аналогичная другим датчикам. При поступлении от него некорректной информации на блок управления ЭБУ не может отдавать команды для формирования оптимальных оборотов и создания топливовоздушной смеси. Поэтому вполне вероятно, что при его неисправности могут появиться повышенные обороты на холостых.
11. Датчик температуры охлаждающей жидкости. При выходе его из строя на ЭБУ будет подаваться информация (или формироваться в нем автоматически) о том, что тосол или антифриз еще недостаточно прогрелись, поэтому о двигатель будет работать на повышенных оборотах чтобы якобы прогреться до рабочей температуры.
12. Снижение эффективности работы водяной помпы. Если по какой-либо причине снизилась ее производительность (она стала прокачивать недостаточное количество охлаждающей жидкости), например, износилась крыльчатка, то система прогрева холодного двигателя также будет работать неэффективно, и следовательно, мотор долго будет работать на повышенных оборотах. Дополнительным признаком этого является то, что печка в салоне греет только при нажатой педали газа, а на холостых оборотах она остывает.
13. Термостат. При непрогретом двигателе он находится в закрытом состоянии, позволяя циркулировать ОЖ только по двигателю. При достижении антифризом рабочей температуры он открывается и жидкость дополнительно охлаждается проходя по полному кругу системы охлаждения. Но если жидкость изначально движется в таком режиме, то двигатель будет дольше работать на повышенных оборотах до полного прогревания. Причины неисправности термостата могут заключаться в том, что он заедает или полностью не закрывается.
14. Электронный блок управления. В редких случаях причиной того, что при заводке двигателя высокие обороты может быть ЭБУ. В частности, сбой в работе его программного обеспечения либо механическое повреждение его внутренних составляющих.

Как устранить высокие обороты на холодную

Устранение проблемы повышенных оборотов при заводке холодного двигателя всегда зависят от причин. Соответственно в зависимости от вышедшего из строя узла необходимо будет произвести ряд проверок и ремонтных мер.

Первым делом проверьте состояние дроссельной заслонки и ее работу. Со временем на ее поверхности скапливается значительное количество нагара, который стоит удалить при помощи карбклинера либо другого подобного чистящего средства. Как говорят: “В любой непонятной ситуации почисть заслонку дросселя”. А также может клинить шток в воздушном канале. В зависимости от конструкции конкретного двигателя их система управления может быть механической либо электронной.

Если конструкция подразумевает использование приводного тросика, то не лишним будет проверить его целостность, общее состояние, усилие натяжения. Когда управление заслонкой происходит при помощи различных электроприводов либо соленоидов, то стоит проверить сделать их проверку мультиметром. При подозрении на неисправность какого-либо из датчиков его стоит поменять на новый.

При соответствующих симптомах в обязательном порядке проверяют факт подсоса воздуха во впускном тракте в местах соединения.

Также стоит уделить внимание и системе охлаждения, в частности таким ее элементам как термостат и помпа. Неправильную работу термостата вы точно определите по плохой работе печки. А при проблемах с помпой будут видны подтеки либо посторонний шум.

Заключение

Необходимо понимать, что кратковременные высокие обороты на непрогретом двигателе — это нормальное явление. И чем ниже температура окружающего воздуха — тем больше времени повышенные обороты будут иметь место. Однако если время превышает приблизительно пять и более минут, то это уже повод выполнять диагностику. В первую очередь нужно просканировать память электронного блока управления на предмет наличия ошибок в нем. Это могут быть ошибки регулятора холостого хода или перечисленных выше датчиков. Если ошибок нет — нужно выполнять дополнительную механическую диагностику по описанным выше рекомендациям.

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In some cases, the connection will be corroded by excessive debris, dirt or engine grime. 90003 90002 If this happens, it can diminish the electrical signal to the idle control valve and cause increased engine idle speed issues.90003 90002 If you complete each of these troubleshooting inspections and can not locate the source of your high engine idle speed, proceed to the next most common method documented below. 90003 90024 Method 2 of 3: Troubleshoot for a vacuum leak 90025 90002 For those who may not know, the rate of airflow through the typical internal combustion engine is vital in order to regulate and factor the amount of power it can generate. Manifold vacuum is present on every engine on earth that uses a throttle system to regulate the flow of fuel and the amount of power the engine makes.As a throttle is opened, the ambient air outside fills the intake manifold and are combined with liquid fuel. At this point the two create a vapor. However, it also increases the pressure inside the manifold (or fills the vacuum). 90003 90002 A system of vacuum lines and storage tanks helps to regulate the vacuum pressure inside the motor. On a fuel injected motor, a vacuum leak can cause the engine’s RPM at idle to increase. In fact, it’s possible to double the idle speed if the leak is significant enough.When a vacuum leak is detected, the O2 sensors on the engine will detect extra oxygen is entering the intake manifold. To adjust, it asks the idle control valve to supply more fuel in order to maintain the fuel curve. The result is that the engine’s idle speed is increased. 90003 90002 Most mechanics typically look for a vacuum leak first when they have a customer that has a high engine idle speed issue. There are a few troubleshooting methods they use to pinpoint the source of the vacuum leak so that it can be diagnosed and repaired.90003 90002 To troubleshoot a vacuum leak, complete the following steps: 90003 90002 90089 Step 1: Pinpoint the vacuum sources on your vehicle 90090. Depending on your vehicle, you may have as many as 10 different vacuum line connections that might be leaking. 90003 90002 The leak can come from a connection or the vacuum line itself. Before you try to diagnose any vacuum leak, make sure you have a diagram of all vacuum lines on your specific vehicle that you can check off as you inspect each one.90003 90002 90089 Step 2: Complete the vacuum leak check inspection 90090. This method might seem a bit outdated, but it’s arguably the best way to find a vacuum leak without having expensive diagnostic equipment. To complete this step, you’ll need to have a full can of carb cleaner, a pair of safety glasses and safety gloves. Here is how it’s done: 90003 90008 90009 90002 Make sure your engine is running 90003 90012 90009 90002 Spray the carb cleaner onto all vacuum line connections based on your engine’s diagram.While you are spraying each vacuum line or connection you’ll be looking and listening for the engine RPM to suddenly drop; and then increase. Carb cleaner is essentially a solvent, but it also can act as an accelerator fuel. When the vacuum line is leaking, it’s sucking in outdoor air into the intake. When you introduce fuel to the equation, it will increase the RPM. 90003 90012 90021 90002 The important thing to remember during this test is not to spray the carb cleaner near any exhaust pipes or hot objects on the engine.90003 90002 If you’ve completed the vacuum leak test and found a vacuum line that is broken, damaged or loose, repair it and see if the high idle speed issue is resolved. If not, proceed to check the final possible issue. 90003 90024 Method 3 of 3: Troubleshooting issues in the throttle cable or throttle body 90025 90002 The final mechanical component that might be causing an engine idle speed to be higher than it should is the throttle body or throttle control sensor. On most domestic and foreign cars, trucks, and SUVs, the throttle body is located on top of the engine, directly on top of the fuel injection manifold.When the throttle system is damaged, it can cause the idle to be higher or lower than it should be. It’s also possible that some attachments like the air intake tube or air cleaner can be the culprit of similar symptoms. 90003 90002 In order to troubleshoot issues with the throttle system on your vehicle, complete the following steps: 90003 90002 90089 Step 1: Determine all components that comprise your vehicle’s throttle system 90090. In general, most throttle systems include: 90003 90008 90009 Throttle body 90012 90009 Throttle control module 90012 90009 Throttle actuator 90012 90009 Throttle cable 90012 90009 Air intake housing 90012 90021 90002 90089 Step 2: Examine each component physically to see if any electrical connection or wiring harnesses are loose or damaged 90090.Most accelerated idle issues in this area will be caused by a wiring harness that is damaged or loose fitting. 90003 90002 Check the connection to determine if this is the case with your vehicle. 90003 90002 90089 Step 3: Clean the throttle body 90090. Although this is not always a troubleshooting step, completing this process will allow you to inspect the condition of the throttle blades (which can cause a high engine idle speed). 90003 90002 Follow the steps in this article for cleaning the throttle body.90003 90002 After you’ve gone through all of the above methods, you should be able to pinpoint a mechanical issue that might be causing your engine to idle higher than it should. If you’ve gone through all of these steps, it could be caused by a malfunction inside your on board computer. Unfortunately, this is a step that should only be completed by a professional mechanic. 90003 90002 If you’ve read the instructions above and do not feel comfortable completing the troubleshooting inspection, or just would rather have a professional mechanic do this for you, contact one of our local professional mechanics to complete your high engine idle speed inspection.90003 .90000 Engine idle speed is high or low Inspection Service & Cost 90001 90002 What is engine idle speed and how is it maintained? 90003 90004 Engine idle speed is the speed, measured in revolutions per minute (RPM) an engine is designed to run at when the engine is fully warmed up and the vehicle is stopped in park or neutral. Typically, the idle speed will be set at a value in the range of 600 to 800 RPM, but the exact value will depend on the number of engine cylinders and whether the vehicle is equipped with a manual or automatic transmission.Idle speed is maintained by the throttle body working in conjunction with the vehicle’s powertrain control module. 90005 90002 How do mechanics adjust or repair incorrect idle speed? 90003 90004 The repair procedure depends on the exact cause of the high idle. The below lists common causes of high idle and in each case, the appropriate vehicle system, components, and parts involved would be inspected, removed for repairs, and / or replaced as needed. 90005 90004 90011 Faulty Fuse: 90012 In the majority of vehicles, engine idle speed is controlled via an idle control valve (ICV).A faulty or blown fuse in other electronically controlled systems can cause the Idle Air Control (IAC) motor to malfunction, leading to a higher than normal engine idle speed. 90005 90004 90011 Faulty Idle Air Control Valve (ICV): 90012 Some cars are equipped with an idle air control valve to maintain idle speed. This part can malfunction due to excessive carbon buildup in the intake manifold. 90005 90004 90011 Vacuum Leak: 90012 On any engine, a vacuum leak will cause a high engine idle as the oxygen sensor detects lean operation and the engine computer then tries to compensate, which can result in abnormal idle.90011 Malfunctioning Throttle: 90012 A malfunctioning throttle system can cause both a high or low idle as well as an engine stall. A dirty air intake or cracked air intake tube is often the culprit. 90011 Computer Malfunction: 90012 If the powertrain control module is malfunctioning, idle speed may be affected. 90005 90002 Is it safe to drive with incorrect idle speed? 90003 90004 No. High idle speed could make your vehicle difficult to control and were the idle speed to suddenly and unexpectedly increase to really high levels, you could experience unintended acceleration.Even moderately high idle speed, that is up to 1,200 RPM will make it more difficult to slow your vehicle when stopping and, once stopped, there remains the risk of your foot coming off the brake and the car jumping ahead. High idle speed also wastes gas and can be distracting as the vehicle does not perform as expected. 90005 90030 When addressing idle speed issues, keep in mind: 90031 90032 90033 Related functions, such as the idle up function when the air conditioner is turned on, will be inspected by a mechanic during the repair of a high idle problem.90034 90033 Prior to replacing parts, such as the throttle body, the mechanic will also need to rule out electrical causes of incorrect idle speed as well as physical causes such as vacuum leaks. 90034 90037 .90000 Why Does My Engine Start But Then Stop? 90001 90002 90003 Checking the IAC (for Engines With Multiport Injection Systems, Most Modern Engines): 90004 90005 90002 In most cases, the problem here is associated with the idle air control (IAC) valve. 90007 The IAC valve is controlled by the computer and allow airs to bypass the throttle valve under idle or cold temperature conditions to prevent a rough idle or keep the engine from stalling. You can test the IAC valve using a digital multimeter: 90005 90009 90010 First, unplug the IAC electrical connector.90011 90010 Turn the ignition key to the On (run) position but do not start the engine. 90011 90010 Set your voltmeter to 20 Volts range (or above 15 Volts) on the DC (direct current) scale. 90011 90010 Connect your black meter lead to ground (engine metal surface or battery negative post, for example) and with the red meter lead probe the terminals on the harness side. 90011 90010 You should get around 10 to 12 volts, approximately, from one of the terminals. This is the incoming signal from the engine control module (car computer).If not, there are problems in that side of the circuit. 90011 90020 90002 Now measure the condition of the valve by measuring resistance across the IAC connector terminals. 90005 90009 90010 Set your voltmeter to ohms for this measurement. 90011 90010 You should get anywhere from 6 to 13 ohms of resistance. 90011 90020 90002 90003 To check for a possible internal short: 90004 90005 90009 90010 Check for resistance from each IAC connector terminal and the IAC valve body with your voltmeter.90011 90010 You should get around 10,000 ohms of resistance. 90011 90020 90002 90003 Checking the internal physical condition of the IAC valve: 90004 90005 90002 A blocked IAC may cause the engine to die as soon as it starts if the valve sticks close. IAC valves may fill with carbon deposits overtime, preventing the pintle from moving, or blocking valve passages. 90005 90002 On most vehicle models, the IAC valve is readily accessible and can be removed easily by unscrewing a couple of mounting bolts.90005 90009 90010 First, turn the ignition key off and remove the key. 90011 90010 Unplug the IAC valve electrical connector. 90011 90010 Unscrew the valve mounting bolts and remove the valve from the vehicle. 90011 90010 Check the valve’s pintle and housing for carbon buildup. If necessary, clean the valve with carburetor cleaner and a soft rag to remove deposits. 90011 90010 Also, check the valve O-ring. It should be soft and in good condition. Otherwise, replace it. 90011 90020 90002 Consult your vehicle repair manual for the recommended testing procedures for your particular vehicle model, if necessary.90005 90002 Your particular fuel injection system may have other necessary adjustments. For example, you may need to adjust 90005 90063 90010 the idle speed 90011 90010 the throttle cable 90011 90010 the throttle plate stop 90011 90010 the idle air-fuel mixture 90011 90072 90002 Consult your vehicle repair manual, if necessary. 90005 90002 90003 Troubleshooting the ECT (Engine Coolant Temperature) Sensor 90004 90005 90002 The ECT measures engine operating temperature and sends this information as electrical data to the computer.The car computer uses this information, and information from other sensors, to adjust ignition timing for better engine efficiency. 90005 90002 Thus, a bad ECT sensor can have a direct impact on engine performance. If the sensor causes a lean air-fuel mixture the engine may idle rough or stall. 90005 90002 Most ECT sensors use a thermistor to vary the voltage signal sent to the computer according to engine coolant temperature. The higher the coolant temperature, the lower the sensor resistance and higher the signal voltage.90005 90002 To test the ECT sensor: 90005 90009 90010 Locate the sensor. It’s usually close to the thermostat housing. 90011 90010 With the engine turned off and cool, unplug the ECT sensor electrical connector. 90011 90010 Set your digital multimeter (DMM) to the ohms scale and measure resistance across the sensor terminal. Make a note of the resistance value. 90011 90010 Plug in the sensor electrical connector and start the engine. Let the engine idle for about 15 or 20 minutes so that it reaches operating temperature.90011 90010 Shut off the engine. 90011 90010 Unplug the ECT electrical connector and measure resistance across the sensor terminals as you did in step 3. 90011 90010 This time, sensor resistance should be considerably lower. For example, depending on your particular sensor configuration and engine model, the sensor may have 40K ohms when the engine is cold but 2K ohms when hot. 90011 90010 Compare your results to the specifications listed in your vehicle repair manual. 90011 90020 90002 A failing ECT sensor can trigger the check engine light.If your sensor checks Okay during your tests, but the computer says there’s a problem with it, check the sensors circuit between the ECT and the computer for bad connections or damaged wire. 90005 90002 Also, check that the computer is sending the correct reference voltage to the sensor. 90005 90063 90010 Unplug the ECT sensor electrical connector. 90011 90010 Turn the ignition key to the On position, but do not start the engine. 90011 90010 Measure the voltage at the harness connector (the one leading to the computer) with your voltmeter.90011 90010 Usually, you should read about 5 volts at the connector. If not, there’s a problem in the circuit. 90011 90072 90002 90003 Checking for a Stuck EGR Valve 90004 90005 90002 The exhaust gas recirculation (EGR) systems reintroduces exhaust gases into the combustion chambers to reduce engine temperature and poisonous emissions. 90005 90002 It is common for the EGR valve passages to get blocked from carbon buildup. Carbon deposits may prevent the valve from closing, causing the engine to stall at idle.Also, an EGR valve may leak through the base, causing the engine to stall at idle, at deceleration, or during a quick stop. 90005 90002 If you’ve never checked under the valve, or it’s been a few years since you last checked, it might be a good idea to take a look now. But make sure to have on hand a gasket replacement. You may need to install a new one. If you can not find one for your particular vehicle model, you still can buy gasket paper at your local auto parts store and make the gasket yourself.90005 90063 90010 Most EGR valves are accessible and not difficult to remove. Check the EGR valve configuration for your particular model, though, to make sure you have all the tools necessary for the job. Usually, all you need is a couple of wrenches, a ratchet, the appropriate socket sizes and, sometimes, a pipe wrench to disconnect the valve from the exhaust pipe. Consult your vehicle repair manual, if necessary. 90011 90010 Remove carbon deposits from under the valve and intake ports using carburetor cleaner.Make sure not to allow carburetor cleaner to reach the valve diaphragm or any electrical circuits, depending on your particular model, or you may ruin the valve. 90011 90010 Reinstall the valve using a new gasket, if necessary. 90011 90072 90002 90003 Checking the EGR Valve: 90004 90005 90002 Depending on your particular EGR valve configuration, you probably can stick your finger through the underside of the valve and try to move the internal diaphragm. If the diaphragm does not move, it may be stuck.90005 90002 Here are a couple of alternative methods to check for diaphragm movement: 90005 90063 90010 Operate the accelerator linkage with your hand to increase engine speed. You may be able to see the diaphragm moving using a mirror placed under the EGR valve. If you can see the diaphragm with the mirror, but you can not see it moving as you operate the accelerator linkage, the diaphragm might be stuck. 90011 90010 You can also use a hand-held vacuum pump. You can do this test with the engine off and using a mirror to watch diaphragm movement.Disconnect the vacuum hose form the valve and connect the vacuum pump instead. Apply about 15 in-Hg of vacuum to the EGR valve while watching for diaphragm movement with the mirror. If the diaphragm does not move, it might be stuck. 90011 90072 90002 Another cause for the valve diaphragm to fail is wear or damage that causes it to leak exhaust gases. A quick way to test for a leaking diaphragm is using carburetor cleaner. 90005 90063 90010 Block the wheels using wooden blocks. 90011 90010 Set your transmission to Park (automatic) or Neutral (standard).90011 90010 Start the engine and pop the hood open. 90011 90010 Spray a quick burst of carburetor cleaner under the valve, towards the diaphragm. 90011 90010 If the engine RPMs increase when you spray, the diaphragm is leaking and you need to replace the valve. 90011 90072 90002 90003 Bad Catalytic Converter 90004 90005 90002 A bad catalytic converter can also cause you problems at idle. Depending on the particular problem, it may show other symptoms as well: 90005 90063 90010 a smell of rotten eggs 90011 90010 rattling sounds 90011 90010 poor engine power 90011 90072 90002 One of the most common problems with a catalytic converter is a plugged unit.The internal substrate becomes partially restricted or disintegrates. 90005 90002 Usually, problems with the catalytic converter trigger the check engine light (CEL). The computer may store a P0420 through P0423 code. If you find a catalytic-converter-related code, do troubleshoot the catalytic converter before replacing it, to confirm that the cat is in fact bad. Catalytic converters are expensive and you need to make sure that some other components is not involved in the problem. If necessary, consult your vehicle repair manual.90005 90002 90003 Checking the IAC on Vehicle Models With Throttle Body Injection (TBI) Systems: 90004 90005 90002 Many vehicles equipped with TBI systems also have an IAC valve controlled by the computer. 90005 90063 90010 You can use the test described in the previous section, if your vehicle has an IAC valve. 90011 90010 Besides, some of these systems may have an idle speed adjustment (consult your repair manual), 90011 90072 90002 Usually, you can adjust idle speed by hooking up a tachometer (some digital multimeters have this feature) to the engine.Then, you can turn the idle speed screw on the throttle body or carburetor until the RPMs are set according to specifications. 90005.