What does it mean when your car Idles smooth?

Smooth idling indicates that your engine’s fuel and air are mixing just right. What is rough idling? If your vehicle’s idle is rough, possibly rising and falling, or having difficulty maintaining a steady rate of rotation, you may have a problem that needs fixing.

How can you tell if your car has a rough idle?

While some cases are less severe than others, a rough idle is usually identifiable by a shaking and bouncing sensation in the vehicle. You may also notice odd sounds, as well as inconsistent RPM counts.

What should the rate of revolutions be on an idle engine?

When you start your engine, and just let it run without pressing on the accelerator or putting it into gear, that is idling. A properly idling engine should be able to maintain a steady but low rate of revolutions, somewhere in the vicinity of 1,000 RPM. Your tachometer needle should be steady and not jumping around.

What causes a car to stall at idle?

The way diesel engines produce power is different from gasoline engines. Every time the injectors push fuel and air into the chamber, the spark plugs deliver the electrical current. This keeps the engine running. If you have a weak or poor quality spark plug, then it is possible that it will lead to car stalling.

What causes a leak in the intake manifold?

These leaks can result from a variety of causes, some of which are: 1 Hose wears out, gets brittle and cracks 2 Hose connection works loose 3 Leaking intake manifold gaskets 4 Leaking vacuum supply tank More

Why does my check engine light light up when I idle?

This is primarily to make sure that the emission controls are working properly, but a rough idle can cause a malfunction code to be sent to the computer. If this happens, your “Check Engine” light on the dashboard will light up.

What causes a MerCruiser 4.3L CARB to stall?

Problem started easter weekend (last week) out on the water 2. Have trouble starting, but engine seems to run fine when under throttle (ran great on the water) 3. When in neutral/idle, will stall out after 10 seconds or so. 4. When it does idle, its very weak…around 400 rpms (should be 650)

Which is worse rough idle or perfect idle?

Very rough idle with a repetitive cycle that is smooth for a couple of seconds then misses badly, occasionally stalling. Worse problem is bad hesitation when accelerating after throttle at idle position, sometimes stalling. Worst after stationary idle, but also after moving at low to medium speed with closed throttle and then accelerating.

Is the drivig engine smooth at low idle?

So smooth you could balance a coin on the engine even at low idle revs of around 650 rpm. In fact drivig with the TPS disconnected is quite acceptable, except that automatic gear change down does not happen (as expected). Have had the car for approx 13 years and has been a great, reliable family car.

What causes engine revs to drop when idle?

3) Once at normal operating temperature, the engine misses badly while idling. It idles smoothly for a second or two, then misses, which causes the revs to drop suddenly, and then the control system seems to increase the idle speed to counteract the drop in revs for a second, and then the cyle repeats.

What causes rough engine idle or TDC code?

So, should the engine misfire, rough engine idle or (TDC) code; point to an air leak in the intake manifold gasket, following the below directions. A very common cause of a leaking intake manifold is the gaskets and bolts used from the factory.

Is it normal to have a rough engine idle?

Consequently, rough engine idle, is not a normal operating condition. As a result, there can be a variety of reasons for a, rough engine idle. It is best to try to diagnose and fix a rough engine idle; before it gets worse and before it gets expensive!

What should I do if my car idles for no reason?

When looking for solutions for a rough engine idle; make yourself a checklist to narrow down the possibilities. While a rough idling engine may seem to be a simple inconvenience; it often indicates a deeper problem within the engine. The vehicle should be inspected and repaired as soon as possible.

Why is the idle speed of my car so high?

Step 2 – The idle air control motor (valve) is responsible for controlling the engine idle speed, if this part fails or becomes weak the engine idle speed could become erratic, additionally, this condition may or may not trigger the MIL (check engine, service engine soon light.)

What to do if your car engine has rough idle?

If you own an old car and are experiencing rough idling, it is a good idea to clean the carburetor and check the hoses for damage or dirt buildup. Rough idling is a serious issue and should not be ignored for a long time. If the problem persists and is not fixed, it can lead to engine failure as well.

Why does my car idle at a higher RPM?

This also creates a vacuum within the intake manifold. These hoses can wear out over time and a leak may develop. If too much air gets mixed in with the fuel, it will cause your engine to misfire. This will result in a rough idle, usually at a higher RPM.

What happens to the engine when left in idling position?

When the engine is left in idling position, it maintains a steady but low rate of revolution approximately 1,000 RPM. The RPM needle stays constant, and this indicates that the vehicle’s engine is receiving the correct amount of air and fuel.

Why is the exhaust gas recirculation valve on at idle?

The Exhaust Gas Recirculation Valve is a vital emission control device. It allows the exhaust gas to enter into the intake manifold, with the sole purpose of reducing emissions from the motor. However, this EGR valve isn’t supposed to operate during idle, at wide open throttle or before the engine is warmed up.

Why is my 5.3 L missing and rough idle intermittently?

5.3 L Missing and Rough Idle Intermittently I have changed Spark Plugs,Wires ,Coil Packs, and removed Fuel Injectors and soaked overnight. Engine code is a P0304. Misfire Cylinder #4. Most of the time around town is alright. When i put it on highway, it will surge like its cutting off and then pick right back up and be fine. Fuel Presure is 55 psi.

Is the EGR valve supposed to run during idle?

However, this EGR valve isn’t supposed to operate during idle, at wide open throttle or before the engine is warmed up. If it runs at any of these times, the performance of the engine is affected.

What are the symptoms of a rough idle engine?

It is possible for you to test the EGR valve at home, using a hand held vacuum pump. Other symptoms: An EGR stuck open may include a rough idle, rough performance at low engine speeds, stalling at idle, increase in fuel consumption, fuel odors, and possibly a check engine light on. 4. MAF Sensor

Why is my car idling for no reason?

There can be a variety of reasons why your vehicle is idling roughly. The downsides of a rough idle can be reduced fuel economy, poor performance, starting issues, or potential major engine problems in the near future. It is best to try to diagnose and fix a rough idle before it gets worse and before it gets expensive! What Is idling?

Why is my Chevy Silverado running rough at idle?

Really, your Silverado will be running rougher at any RPM, but a misfire will be most pronounced at idle. Spark Plug Wires – While not every model and engine combination of vehicles today comes with spark plug wires (a lot are now coil on plug), if your Silverado happens to have them, they can go bad and cause a rough idle.

What’s the problem with a ” rough idle “?

Rough idle, bad hesitation… This problem started suddenly. Very rough idle with a repetitive cycle that is smooth for a couple of seconds then misses badly, occasionally stalling. Worse problem is bad hesitation when accelerating after throttle at idle position, sometimes stalling.

Why is my Ilde so bad at idle?

Also very hard to start because of periodic ‘backfire’ while cranking that brings engine to standstill. Idle is perfectly smooth for first 1 – 2 minutes after overnight cold start, before missing at idle starts. Missing and hesitation worse the hotter it gets. Turning on air condtioning makes ilde worse, with more frequent stalls.

What causes an engine to vibrate at rough idle?

It only takes a minor problem like a fouled spark plug to cause your engine to vibrate. Idle problems may originate in a worn out component, a failed part, or a blown gasket. The number of potential sources of a rough idle can make your diagnostic a little difficult.

What does it mean when your car engine is idling?

Intake leak When you start the engine and let it run without pressing the pedal, it is called idling. When the engine is left in idling position, it maintains a steady but low rate of revolution approximately 1,000 RPM. The RPM needle stays constant, and this indicates that the vehicle’s engine is receiving the correct amount of air and fuel.

When does a car have a rough idle?

November 27, 2017. It’s easy to tell when your car has a rough idle: When you start the engine, it won’t run at a steady rate. It may almost stall, or it may run at varying RPMs without your putting your foot on the gas, or it may do both.

What happens if you leave your car idled for a long time?

Some motorists have been unpleasantly surprised to discover squirrels and rodents under the hood after leaving a vehicle idled for a long time. Several manufacturers have adopted wiring with organic-based insulation that appears to encourage rodents to chew on it, potentially causing short circuits and other issues.

How can I tell if my car is idling?

When you start your engine, and just let it run without pressing on the accelerator or putting it into gear, that’s idling. A properly idling engine should be able to maintain a steady but low rate of revolutions, somewhere in the vicinity of 1,000 RPM. Your tachometer needle should be steady and not jumping around.

However, this EGR valve isn’t supposed to operate during idle, at wide open throttle or before the engine is warmed up. If it runs at any of these times, the performance of the engine is affected.

Why does my car engine run rough while idling?

When your car engine runs as it should, everything should be smooth without any noise. When any number of things goes wrong, the engine can start running rough, especially while idling. By understanding the causes of a car engine that has a rough idle, you can resolve the issue easily.

Why does my engine flutter when I idle?

Hi there. Usually when your engine struggles to maintain a smooth idle while in gear it is attributed to fuel system issues ranging from dirty fuel injectors, to idle control valve that is damaged or a mass air flow sensor issue. It can also be caused by a vacuum leak or dirty air filters as well.

When does the engine fluctuate at a red light?

The fluctuation would occur during warm and cold days and even after the car had sufficient time to properly warm up. I even took it for a long road trip 1,000 + miles only stopping for gas and it would still fluctuate when stopped at a red light. At this point in time no engine light was present nor rough/shacking vibrations.

When is the best idle time for a truck?

Rough idle when in drive..but idle is fine when in nuetra… Truck idle is rough when in drive with no acceleration (stop signs, red lights, traffic) but idle is fine when in park or nuetral. . Check engine light just started flashing recently

Share it! It’s easy to tell when your car has a rough idle: When you start the engine, it won’t run at a steady rate. It may almost stall, or it may run at varying RPMs without your putting your foot on the gas, or it may do both. There can be a variety of reasons why your vehicle is idling roughly.

Is there a problem with rough idle when warm up?

So, once there’re visible signs of rough idling, trouableshoot the problem without causing any further delay. As reported by Car From Japan experts, most Makes getting this engine rough idle after warm up are: Though the problem is not common but drivers of the Makes had their car serviced at garages for Rough Idle When Warm.

Why does my vacuum have a rough idle?

Leaks in these hoses and in other parts of the vacuum system can be another cause of a rough idle, often because of a lean air-fuel mixture from excess air entering the system.

What should the RPM be on an idling car?

What should I do if my car runs rough at higher RPM?

Its probably somewhat small b/c it apparently doesn’t disturb the cold idle too much (richer mixture at that point). A smoke test at a shop might be the fastest/easiest way to go, but you have to pay for those. Some people spray something like carb cleaner around vacuum connections & manifold looking for changes in idle.

How does idle speed work on a GMC Truck?

Scan it for codes. The control module controls idle speed with an idle air control (IAC) valve. The desired RPM is based on sensor inputs and the actual engine RPM. Four circuits are used in order to control the IAC valve, allowing a precise amount of air into the intake manifold.

What are the symptoms of a bad idle air control valve?

Below are the top 5 symptoms of a bad idle air control valve which you will easily notice. Since the idle air control valve is supposed to manage the idle speed of the engine, a bad valve will certainly throw that out of whack. It will cause the idle speed to randomly fluctuate to different speeds rather than stay at one constant speed.

Can a bad air control valve cause an engine to stall?

Sometimes the engine stalling will happen on its own while other times, increasing the load on the engine will cause it to stall. For example, if you turn on your heater or air conditioner when you have a bad idle air control valve, then your engine will probably stall immediately afterward.

What does it mean when your car is idling but not running?

When the engine is running but the vehicle is not moving, this means the engine is idling. During this time, the number of revolutions per minute (RPM) inside the engine will change.

Why does the temperature drop when the engine is warm?

Every time you start the engine again the coolant flows, the fans turn on, and the temperature drops. When this heat dissipates and is absorbed under the hood, it is trapped causing this cycling effect. Components that contain heat sensitive materials include parts like coils, injectors, igniters, and some sensors.

What are the symptoms of a bad fuel gauge sender?

Usually a bad or failing fuel gauge sender will produce a few symptoms that can alert the driver of a potential issue. 1. Fuel gauge behaves erratically One of the first symptoms of a problem with the fuel gauge sender is a fuel gauge that behaves erratically.

Can a bad fuel pressure regulator cause a rough idle?

Once warm, a bad fuel pressure regulator can cause a rough idle by leaning out the mixture due to low fuel pressure. A Fuel filter would not cause a rough idle when warm. A clogged fuel filter would cause far more problems on a cold start when fuel demand is higher.

How can you tell if your car engine is idle?

You can often also feel the strange vibrations inside your car while sitting in the driver seat. However, modern cars do often have great engine mounts, and you do sometimes have to open the hood to check if the engine is vibrating or even jumping on idle.

What causes a rough idle when the engine is cold?

The cold-start injector is in charge of smoothing out a rough idle when the engine is operating at a temperature that is below optimal levels. One the engine reaches the right temperature, the cold-start injector turns off. If the injector is dirty or you are dealing with a bad fuel injector, it will not give the extra fuel needed.

Why does my A4 have white smoke at idle?

I could live with that, if that’s all it was, however as the engine starts playing around it also starts puffing white smoke. you can see it licking over the boot and when I accelerate it covers the car behind. Now I must be clear this only happens when the car is warming up, from cold it’s fine and at temp no juddering and no smoke at idle.

Is it normal to have rough idle at Warm start?

At cold start is sounds/feels normal. At any RPM other than idle it also sounds and feels normal. When idling warm it is very rough, periodic vibration that feels like it is stalling. It has not actually stalled, there is no smoke at warm idle. Some smoke at acceleration from idle but none accelerating at higher rpms.

What causes a rough idling of an engine?

Spark Plugs. A rough idling engine can be caused by spark plugs or spark plug wires. Spark plugs use the electrical current received from ignition coils to ignite the air/fuel mixture within the combustion chamber.

Is it normal for a PowerStroke van to idle rough?

My 97 7.3l powerstroke van has started to idle rough but only when warm. At cold start is sounds/feels normal. At any RPM other than idle it also sounds and feels normal. When idling warm it is very rough, periodic vibration that feels like it is stalling. It has not actually stalled, there is no smoke at warm idle.

Why does my car’s exhaust smell like gas?

The fuel injectors or carburetor on your vehicle regulates fuel flow into the combustion chamber. If an injector or carburetor begins leaking fuel into the combustion chamber, it creates a rich running condition. This results in a rough idle and unburned gas making it into the exhaust, creating a gasoline smell in the exhaust.

What should I do if my old tractor won’t start?

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What causes a rough idle on an air conditioner?

A clogged air filter will not allow clean air to pass through causing a rough idle. To remedy the situation, have your air filter replaced with a new one and also have the housing serviced to clean any dirt buildup. 7. Dirty Oxygen Sensor

What causes a car to run at a rough idle?

A PCV valve leak can cause the air-fuel mixture to run too lean, and this will cause a rough idle. Proper periodic servicing of the PCV valve will prevent this situation from occurring.

What’s the idle speed on a new car?

Couple of notes: Initially, it ran fine till it warmed up, at about 1200 rpm , then back to the terribly rough idle…. feels like it’s missing, too. On several cylinders. Would cycle between 500-800 rpm, kinda hunting and gagging around, at about a 1.5 sec interval. Let it idle for about 15 mins straight, not touching anything.

Why does my car idle rough when the AC is on?

A rough idle when the air conditioning is on may be caused by: A faulty or dirty IAC valve A dirty throttle body A faulty cooling or condenser fan

Why does my car shake when I idle?

By adjusting the idling speed on the carburetor and cleaning the fuel intake system, you can solve this problem. The carburetor is a device that mixes the air and fuel for the proper air to fuel ratio in order to use for combustion.

What should I do if I have a rough idle?

1) Spark plugs, plug wires, rotor & ignition coils – Clean and inspect. 2) Check compression – poor cylinder head compression is common for an older car. Big job to fix this. 3) Use a good fuel-injector cleaning treatment into the tank – take it for a good run. 4) Change fuel filter. 5) Remove and clean injectors – might need to replace injectors.

How long should it take for idle to smooth out?

Idle should smooth out over 10-12 miles; shifts should be immediately smoother. Check the following in this order: 2) Check your brake pads! 3) Check thrust arm bushings. (Some call them upper control arms). Bushing can go after several thousand km’s 5) Check Struts / Shock absorbers while your there.

What causes rough idle / acceleration in a car?

Mass Air Flow (MAF) sensor is the cause of rough Idle/Acceleration 80% to 90% of the time. My car ran a lot better after this video, but Every once in a while I would still get some chugging – I ended up buying a used MAF sensor at a junk yard. It had low miles on it for about $25. So far it has been running smooth.

Leaks in these hoses and in other parts of the vacuum system can be another cause of a rough idle, often because of a lean air-fuel mixture from excess air entering the system.

What causes a cruise control to stop working?

If that signal is lost, the CCM can’t detect vehicle speed, disabling cruise control. Electrical Problems – As most cruise control systems use electrical or electronic components, any diagnosis should include a thorough check of source voltage, wiring harnesses, and connectors. Anything loose or broken could disable the system entirely.

How does a cruise control system work in a car?

Early systems used a vacuum motor and cable, but these eventually changed over to electric motors. Most recently, with the development of drive-by-wire or electronic throttle control systems (ETCS), cruise control is built into the engine control module (ECM), which controls the throttle body electronically.

What causes the cruise control to stop working?

Most common cause of erratic cruise control? Vacuum leaks caused by deteriorated hoses. Cruise control on your vehicle is a terrific device. It substantially reduces the driver’s workload on longer trips, and can save substantial amounts of fuel and expense over the life of the vehicle–until it stops working.

How does an adaptive cruise control system work?

Adaptive cruise control systems, sometimes called “smart” cruise, use radar or laser detection to maintain safe distances from vehicles ahead. Some adaptive cruise control systems merely reduce engine speed to maintain distance, but some of the newest adaptive cruise control systems can also engage the brakes to slow or stop the vehicle.

What causes a car to have a high idle?

If it stays shut then your engine is not going receive air and it won’t start. When the throttle gets stuck in an open position than your vehicle will receive too much air and cause it to have a high or fluctuating idle. What are signs of a bad Throttle Position Sensor?

Why does my EcoBoost shudder at sudden acceleration?

Sudden acceleration by the driver, changes the intake air flow rate through the CAC which causes the engine to pull in more air. With the moisture sitting in the intake tube, the engine is acting like a vaccum sucking up all this water. Depending on the amount of water that is sucked up causing…

Why does my car sputter when I Turn on the engine?

The fuel filter ‘s job is to filter the fuel going to the fuel injectors and then enter the engine. A clogged fuel filter can cause the engine to get too low fuel pressure or cause a clogged fuel injector. Low fuel pressure will cause the engine to run very leanly, and therefore it may cause the engine to sputter.

Why does my car have a bad smell?

This allows raw, unburned fuel to escape the exhaust. Fouled plugs have a foreign substance — ash, soot, tar, oil or fuel — coating the electrodes, causing excessive resistance and making the spark colder. This results in a rough idle and a fuel smell in the exhaust.

Why does my car have a rough idle when cold?

One of the most common causes of rough idle on a cold engine is a faulty ECT sensor. This sensor signals the car’s computer when the engine’s coolant is cold or hot, so the computer delivers more or less fuel to the engine. A cold engine requires more fuel than a warmed engine.

Why does my car sputter when I start the engine?

Whats happening with mine is the fuel pressure regulator ( or some component in the fuel metering system) is flouling the plugs after sitting for several hours. Once the engine starts and the fire in the cylinder cleans the plugs, it runs fine. You may have the same problem.

Why does my Car start cold in the winter?

Some models of car, depending on the make, model, and year, come equipped with a cold start fuel injector. The main purpose of this fuel injector in your car is to add the right amount of fuel to the engine during the cold engine starting in winter weather.

Is it normal to have a rough idle?

This is definitely not a normal situation. If you are experiencing a rough idle or your RPM is running high, then there are a variety of reasons for why this could be happening. It is not always easy to diagnose the cause because there are so many factors involved here. Below are the top 5 causes that a mechanic would look for.

What should the idle RPM be on a car?

Your engine should normally get to around 700 RPM after you start the vehicle, depending on the model. If your idle is way off and you have one or more of the problems listed above, then you will want to diagnose the issue right away.

When does the RPM go back to normal?

The RPM will usually go back to normal as you accelerate the vehicle, but will increase again after you stop. This is definitely not a normal situation. If you are experiencing a rough idle or your RPM is running high, then there are a variety of reasons for why this could be happening.

Why does my car idle at 700 rpm?

There is an air filter which prevents debris from the air from getting into the chamber. But if this air filter is dirty or clogged, then there will be less clean air passing through it. This will cause the engine to idle rough. Your engine should normally get to around 700 RPM after you start the vehicle.

Why does my F150 shake when I idle?

Why an F150 shakes when idling. If you notice that your F150 is shaking more when it’s idling, then it may be caused by: EGR sensor sticking: When the EGR sensor is dirty or damaged it causes the EGR valve to stay open. The valve and sensor must be cleaned with a climtool or replaced to correct this concern.

What causes a rough idle in a direct injection engine?

In direct injection engines the fuel injector delivers gas right into the cylinder, so the valves never get fuel spray. After shutdown, crankcase vapors rise to the top of the engine and settle on the intake valves where they condense and harden. The result is carbon buildup that can cause a rough engine idle.

What’s the downside of having a rough idle?

It is best to try to diagnose and fix a rough engine idle; before it gets worse and before it gets expensive! Also, the downside of a rough idle can be, reduced fuel economy, poor performance, starting issues; or potential major engine problems in the near future.

Why does my Ford F150 shake when I idle?

Here are the main components of the ignition system, as well as what would cause them to make your F150 shake when idling. Fouled plugs can cause a misfire, which in turn causes an idle shake. Spark Plugs – One of the absolute most common causes (if not the most common reason that your F150 may be shaking) is the spark plugs.

What causes rough idle after engine has heated up?

At this point, if you turn the truck off and back on again, it will idle fine UNTIL you rev the engine at all, at which point the truck will start shaking again, and idling really rough.

Is the warrior Idles fine when trying to accelerate?

The warrior idles fine. I’ve adjusted to air mix screw back and forth. It changes the idol but doesn’t seem to improve things when I try to rev it up. 2.25 turns seems to be the sweet spot, as far as idol. The needle is where zoom put it.

When to seek help for a rough idle?

If you need further assistance with your engine running rough after 10 minutes of driving, then seek out a professional, such as one from Your Mechanic, to help you. The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Why does my GMC Canyon stall at rough idle?

No more rough idle. I have a 2007 GMC Canyon and beginning last Summer (in 2011) the Check Engine light started coming on intermittently. Also, whenever I come to a stop, the RPMs run so low that sometimes my truck stalls if I don’t rev the engine a little while I have the brakes applied.

What should I do if my car Idles rough?

Proper repair is straight forward: Pull the intake hose off and thoroughly clean the throttle body so that there are no dark deposits at all, it should show nothing but smooth silver. In severe cases the idle valve will need to be cleaned too, this is not typical though.

How long does a warm engine idle for?

With a steady throttle, it fluctuated between 3 and 3.5 for a couple mins, then bogged out and stalled. Next time I started it, it went to 2k intially then started hunting between 1k and 1500, with about a two sec interval. After a couple mins, fluctuated around 750, but not steady.

What causes a diesel engine to have rough idling?

As diesel engines age, the fuel injection system can start to “gum up”, and the injector tips begin squirting instead of misting. The injection timing can get out of whack. Wear and tear on the piston rings and cylinder walls result in lost combustion. Is the smoke coming out of the exhaust pipe blue?

What to do if your car has rough idle?

Another option is to try to clean your fuel injectors with a fuel system additive like Techron, or something similar. While an additive may or may not have much effect on your rough idle problem, you can consider this as a last-ditch effort before visiting your mechanic.

What to do if your fuel injector is rough idle?

Why does my car make a clicking noise when I idle?

The first noise you described sounds like valve lifter noise. You will hear this sound if the engine is low on oil. Check the oil level and add if necessary. The lifter noise is not heard at higher RPMs because the oil pressure is higher as the engine speed gets higher. If you have high mileage, you could benefit from the next higher viscosity oil.

What does it mean when idle control does not increase?

If the engine idle does not increase, it means there is an issue at the idle control motor of its circuit preventing the signal from changing the idle. You can purchase a bidirectional scan tool at your local auto parts store. Make sure the wiring harness is firmly connected to the idle control motor before conducting this test.

Can a bad idle control valve cause stalling?

This is controlled by the engine’s computer. Sometimes parts go bad, which results in your car idling strangely or stalling. Check to see if your idle control valve is functioning properly before attempting to replace it. Look for a high engine idle. A common symptom of a faulty idle control valve can be a high idle.

Can a failed IAC cause engine stalling at idle?

A problem with the IAC should throw a P0505 code. A failed/problematic IAC can cause engine stalling when off-throttle, and/or excessively high engine rpm, particularly at idle. The IAC, signaled by the ECU, controls the throttle opening at idle.

Can a loose fuel filter cause a car to stumble?

In some cases, the connections on the fuel filter may be loose, causing fuel to leak from the fuel lines or the fuel filter. This can cause engine stumbling issues. If you notice this problem, replace the fuel filter with a new one and retighten the fittings.

What does it mean when your car Idles smooth?