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 does MY BMW 320i misfire when starting?

Should be able to narrow down from there. I had this problem for almost 3 months now, misfire when starting the car, RPM drops very low and fluctuates, vibrates violently like driving an tractor; already sent to 2 different workshops but still not fixed, changed coils, changed spark plugs (3 sets) and VANOS solenoids also.

Why does my car idle with a rough spark plug?

Spark Plugs A rough engine idle, can be caused by, spark plugs or wires. Spark plugs use the electrical current; received from ignition coils to ignite the air/fuel mixture, within the combustion chamber. A plug that is damaged or installed incorrectly, can result in fuel being burned at an inconsistent rate.

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.

What causes a car to backfire when under load?

The valve is the passageway for air to enter the system when the engine is under load. When it’s malfunctioning, it releases air into the combustion chamber even at the time of de-acceleration. It creates the ignition of unburnt fuel and causes a car backfire.

How can I tell if my engine is having a backfire?

Valve issues may also involve poor fuel economy, rough idle, stalling, high oil consumption, hard starting, and exhaust smoke. Valve problems of these type tend to create a more consistent backfire condition. You may diagnose valve problems at home with the use of a compression gauge or a vacuum gauge.

How to diagnose engine backfires with axleaddict?

Car owners usually forget to check the ignition system at the recommended manufacturer schedule. If necessary, consult your car owner’s manual or repair manual. Even if your Check Engine Light is not lit on your instrument panel, scan for possible pending diagnostic trouble codes that can guide you in your diagnostic. II. Injection System Problems

How to fix rough idle on 1996 F-150?

Took the fitting off of air tool, and screwed it in the end of the pipe. Lube the O-ring of an injector, 12-volt power supply (or battery). Set compressor to about 40-50PSI. All my injectors were just fine!

Can a head gasket leak cause rough idle?

Leaking Head Gaskets. Leaking Head Gaskets. Coolant in your oil, oil in your coolant, missing coolant, coolant overflowing out of reservoir, overheating; are all signs of a head gasket leak and they can easily cause a rough engine idle. Also Read – Cylinder Head Gasket Leaks – Know The Signs And Symptoms.

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.

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.

When to use rough idle when in drive?

Q: Rough idle when in drive..but idle is fine when in nuetral or park. Truck idle is rough when in drive with no acceleration (stop signs, red lights, traffic) but idle is fine when in park or nuetral. . Recommended Services. Car idle is rough Inspection.

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.

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

Why does my car idle all the time?

This will cause the fuel and air mixture to burn inconsistently, which will result in an idle rough engine. Vacuum Leak –There are a lot of hoses that help deliver both fuel and air to the internal combustion chamber. One very common cause of idling rough is a problem with a vacuum hose in the vehicle.

What causes a car engine to run rough?

Spark plugs use the electrical current received from ignition coils to ignite the air/fuel mixture within the combustion chamber. A plug that is damaged or installed incorrectly can result in fuel being burned at an inconsistent rate. If the damage is bad enough, you may also notice your engine running rough.

What causes a car to run rough at idle?

What Causes Rough Idle? Misfires. Misfiring is probably one of the most common causes when it comes to rough idling. Faulty Idle Control Valve. An idle control valve is often installed on older vehicles. Faulty Throttle Body or Throttle Body Sensor. Damaged Fuel Injector. Clogged Fuel Filter. Dirty Air Filter. Dirty Oxygen Sensor. Bad MAF Sensor/IAT Sensor.

Why would a car run rough at idle?

Causes of a rough idle. Many different problems could result in a rough idle for your car or truck, including: dirty fuel injectors, clogged air filters, bad spark plugs, and a variety of exhaust system issues.

What causes rough idle when stopped?

You may notice your car idling roughly when it’s in “Park” or when you’re driving it and stop at a stoplight. A rough idle can be caused by damaged spark plugs or spark plug wires or a burned-out valve. It’s important to address the cause as soon as possible to avoid potentially damaging the engine. Engine repairs are almost always expensive.

Why would a car shake while idle?

Broken motor mounts can cause your car to shake violently when it is idling. If the motor mount breaks or gets disconnected from the engine, it can create a distinctive shaking sensation whenever your car is at an idle. To get to the bottom of a motor mount issue, you will need to visit an engine mechanic.

Why does my Dodge truck hesitate to go?

I can feel the whole truck shake, and the rpm rolls from near stalling to 1500+rpms. When you put it in drive, it stumbles a bit while holding the brake. When you go to give it light throttle…it hesitates, surges and stumbles as it tries to get moving. If you give it a lot of throttle, it will push thru it and go.

Why does my Dodge Ram idle when I shift to neutral?

The odd twist of this idle/hesitation problem (and probably the most important part of this issue) is that it clears up completely when I shift to neutral. If it’s in park, it idles horrible and stumbles bad when I try to rev it. Then I put it in neutral and she idles smooth at 625rpm, and will rev normally, with no stumble at all!

What causes engine hesitation on a Dodge truck?

The engine hesitation on your Dodge may be created by problems in one or more components. In most cases, a bad throttle position sensor (TPS) fails to signal the engine computer about throttle operation. Other causes may be bad or worn out components in the ignition secondary system, causing the engine to accelerate poorly and even stall.

Why does my Dodge engine stall when I start the car?

Other causes may be bad or worn out components in the ignition secondary system, causing the engine to accelerate poorly and even stall. These steps will help you inspect these components and solve the hesitation problem on your Dodge vehicle.

What to do if your Dodge engine is not running?

If you do not get any voltage reading, there is an open or short in the circuit. Turn off the ignition switch. Check the TPS sensor resistance. Unplug the sensor electrical connector. Using your ohmmeter, check the sensor resistance by back probing the supply and signal wires at the sensor.

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.

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.

Why does my GMC Sierra 1500 run rough at idle?

The spray smoothing out the rough rpm is an indication of the engine running lean, could be low fuel pressure, could be a vacuum leak. With it running rough at an idle and smoothing out at a higher rpm is a general sign of a vacuum leak.

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 to do if your fuel injector is 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. Follow the directions on the product’s label.

Is the Dodge Ram surge rough idle cure?

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Why is my truck running rough at idle?

Why does my car idle rough at a stop?

Is your vehicle idling rough?

If your vehicle is experiencing rough idling, you’ll probably know it immediately. 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. Normally, a vehicle should have a smooth and consistent RPM rate of around 1,000 . If your vehicle is falling below or rising above this you may be dealing with an idling issue.

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

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.

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 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.

How to troubleshoot an automotive engine high idle?

The troubleshooting procedure for high and low idle conditions are similar, which are included in the following: Step 1 – If the check engine or service engine light soon has illuminated retrieving the diagnostic trouble codes could lead you in the right direction of what the problem is, or is related too.

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.

What causes idle surges on a car ECM?

Idle surging can be caused due to other issues in the car, but if it happens in conjunction with other throttle position sensor symptoms, the culprit is often the TPS. At idle, the ECM will not get the correct information and the throttle will variate randomly causing idle surges.

What causes engine to run rough after warm up?

Most likely, the causes of rough engine idle crops from the basic functional components like direct fuel injectors, PCV valve, EGR valve, Oxygen sensors, vacuum leaks, air filter, and spark plugs or wire. Now, let’s fix the issue when engine runs rough after warm up in sequence and later troubleshoot the actual cause of it. 1.

Why is my V8 running rough at higher revs?

If the “roughness” clears at higher revs you could be experiencing a flooding condition in one of your cylinders. Possibly damage or a short to the injector cable. With your lpg conversion your injector wires would have been tapped into for a signal to control the lpg injectors.

What causes a boat engine to have a rough idle?

A misfire may occur when your engine is idling, causing a rough or uneven idle. Misfires and rough idling are difficult problems to isolate, since they can be caused by many system malfunctions.

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 causes an Audi A4 to idle rough?

A super lean running engine will often idle rough. The fuel injection systems job is to atomize the fuel into fine mist. If a fuel injector has an issue with this process, it will either let too much or too little fuel into the combustion chamber relative to the amount of air.

Why does my Ford Triton engine keep idling?

Well, Ford says that the culprits are defective cam-timing solenoids. Solenoids that work properly help the engine operate at peak power and efficiency. But when something goes wrong and the camshaft timing goes bananas, you should expect lots of drivability issues and over-the-top levels of emissions and exhaust smoke.

What to do if your outboard engine is running rough?

If it isn’t, it will cause your engine to become fuel starved, run rough, and eventually stall. Simply twist it open and monitor your engine for improvement. If your outboard motor isn’t running at its best, check the fuel vent on your portable tank to make sure it’s open.

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.

Why does my car run rough idle when it’s cold?

In addition to the vibrations, you might also notice strange sounds when the car is running rough idle when cold. Along with the strange sounds coming from your engine and under your hood, there might be an inconsistent engine RPM while you are driving and accelerating.

What does it mean when your car idles at low RPMs?

The car will feel rough and bouncy when the engine is running. The car will also idle below its regular speed, display inconsistent RPMs and may produce a shaking, skipping or slipping sound when the vehicle is running. While a rough idling engine may seem to be a simple inconvenience it often indicates a deeper problem within the engine.

What causes car Idle is rough inspection service?

Car idle is rough Inspection Service. A rough idling engine can be caused by a number of issues, some of them are serious while others tend to be minor, but the symptoms remain pretty much the same. The car will feel rough and bouncy when the engine is running.

Why does my car idle when I Turn on the ignition?

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. A plug that is damaged or installed incorrectly can result in fuel being burned at an inconsistent rate.

What causes the idle speed to go up or down?

The idle air control valve is programmed to regulate and maintain the engine idle speed at a constant rate. If the valve fails or has any issues it can cause the idle speed to be thrown off. This may result in an unusually high or low idle speed, or in some cases a surging idle speed that repeatedly climbs and falls. 2. Check Engine Light comes on

What causes an engine to stall at idle?

When the valve fails, it may get stuck close or open, or even leak. It is when the valve remains open when engine idle suffers. Sometimes, the engine may stall at idle because of the lean of the air-fuel mixture.

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 should I look for at rough idle?

Checking the fuel pressure is never a bad idea. The first thing I’d be looking for is a vacuum leak – anywhere in the air intake, intake manifold or vacuum lines themselves. Its probably somewhat small b/c it apparently doesn’t disturb the cold idle too much (richer mixture at that point).

What’s the RPM of a car when it idles?

When the car starts it idles fine at about 1000 RPM. As soon as it warms up, it starts to idle rough, between 500 and 750 RPM. It almost quits running. As soon as you give the car some gas it runs just fine.

Is the Ford PowerStroke 6.0 surging rough idle?

I have a 2004 f-350 with the 6.0. My truck has been been like missing or something like its been cutting out when at an idle and it like shakes the whole truck and even sometimes even dies. Its not giving any codes or anything. And i have my egr unplugged.

What should the RPM be on an idling car?

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.

When does the idle air control valve stall?

However, when the engine RPM drops below the normal range of 800 RPM (for most cars), it is more than likely that you are dealing with an IAC valve problem. In cases where this valve is clogged or is nearing its replacement age, your vehicle will stall instead of idling after the release of the throttle.

What causes a car to rough idle and stall?

My car has an automatic transmission. This issue is normally caused by low fuel pressure or a faulty injector, but since you have just replaced the fuel pump, this may also be a sign of a failing idle air control (IAC) valve.

Why does my car rough idle but no check engine light?

This issue is normally caused by low fuel pressure or a faulty injector, but since you have just replaced the fuel pump, this may also be a sign of a failing idle air control (IAC) valve. This is a unit that is located on or near your intake manifold that monitors the air intake as it is mixed…

Why does my Chevy Silverado have rough idle?

An internal combustion engine needs air, fuel, and spark in order to achieve ignition. When one or more of these variables is off it can lead to a rough idling condition. Most of the time the culprit is going to be the ignition system, although there are a myriad of other causes. We’ll cover the most common causes of rough idle below.

What does it mean when your engine idles rough?

For example, when your engine idles rough, you may notice the problem only shows up before the engine warms up; then idle smooths out. This may indicate a bad ECT sensor as described in Other symptoms in that section. So pay attention to all the symptoms and conditions when given in each component listed to make your diagnostic easier.

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.

Why does my Jeep Liberty have a rough idle?

What are common reasons my Jeep Liberty has a rough idle? While there are a variety of reasons your Jeep Liberty has a rough idle, the most common 3 are a vacuum leak, an issue with the spark plugs, or a problem with the ignition coil. See what others are asking about their Jeep Liberty.

Can a boat engine misfire or rough idle?

Misfire/Rough Idle. Boat engines have the same operating principles as do land vehicle engines, but having trouble with your boat engine can leave you and your family in a precarious predicament. If your car, truck, or SUV doesn’t run up to snuff, you can pull off to the side of the road and call for towing assistance. In a boat with…

How can you tell if your car engine is misfiring?

Rough acceleration is a typical sign that your engine is misfiring. Sometimes, the engine will misfire on idle also; your engine sensors will get faulty values, and the air-fuel mixture will get messed up. This can cause a very uneven idle, which can jump up and down, and the engine may also shut off on idle.

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 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?

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 does it mean when your car idles for a long time?

The idle of a car engine is kind of like a human heartbeat: You can tell what shape it’s in just by listening. Problems with idle speed —things like slow idle, fast idle, rough idle, or stalling after idling for a few seconds—are symptoms that something is wrong with your engine.

Why does my car idle rough when it’s warm?

Note: An additive can sometimes, however, cause a rough idle problem. When the cars idle gets rough, it hard to comprehend the related causes. It is because rough idle when warm can either be caused by one faulty component or through series of problems.

What can I do about rough idle when warm?

If direct fuel injectors are the trouble-maker then, clean them using a blend of powerful solvents and high pressure. Another option to try includes fuel system additives, which clean fuel injectors. Note: An additive can sometimes, however, cause a rough idle problem.

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 does it mean when your car Idles low?

What is a Rough Idle? When somebody says that there vehicle is “idling rough” this usually means that the revolutions per minute (rpm) gauge on your instrument cluster is rising and falling or maybe the car idles really low at first and then smooths out after a few seconds.

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.

What causes a Chevy 350 to backfire when idle?

If a main vacuum hose such as the power brake booster feed line has broken or failing off it will cause a lean backfire due to the additional air allowed into the engine intake manifold. This problem will be accompanied by high or low engine idle and a harder to push brake pedal than normal.

What causes an intake back fire in an engine?

This will help locate the system that is having a problem and needs repair. An intake back-fire explosion can be caused by the fuel air mixture being to lean when the engine is demanding power. Every internal combustion engine runs on a mixture of 14 to 1 which is fourteen parts air to one part fuel.

Why does my ATV keep backfiring at idle?

Take note that most ATVs source fresh air at the junction of mufflers and header pipes. If there’s a leak along the system, the engine will keep backfiring. In some instances, a popping exhaust system indicates that the engine has an extremely lean idle circuit.

Why does my motorcycle engine keep backfiring?

When you are getting too much air and not enough fuel in your cylinder this is called running lean. A lean condition in your engine is terrible for the engine internals. Too little fuel in the cylinder and an excess amount of air can be the culprit to your backfiring problem.

Why is my GM 4.8l engine running too lean?

The engine may be running too lean, due to a leaking intake manifold. Too lean means too much air and not enough fuel; according to the power control module (PCM) calculation. When the engine is cold, not all sensors function. As the engine warms up the oxygen sensors report the lean condition.

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 does it mean when your car is stalling at idle?

Problems with idle speed —things like slow idle, fast idle, rough idle, or stalling after idling for a few seconds—are symptoms that something is wrong with your engine. These should be investigated, diagnosed, and repaired as soon as possible.

How do you do an idle Relearn on a Ford?

Follow these steps to complete an Idle Relearn: With vehicle at a complete stop, set the parking brake. Put gear shifter in “P” (Park), turn off all accessories. Run the engine until it reaches normal operating temperature.

What’s the best way to idle a car?

Run the engine until it reaches normal operating temperature. Allow engine to idle for at least one minute. Turn the air conditioning on and allow the engine to idle for at least one minute. Release the parking brake.

How can I fix rough idle?

Drive the vehicle to a reputable service center that has a code scanner.
Place the transmission in Neutral or Park. Apply the emergency brake and raise the hood.
Start the engine and let it warm up.
Check the condition of each plug.
Reinstall the plugs and start the engine.

Why do rough idle or possible misfire?

Misfiring is probably one of the most common causes when it comes to rough idling. Misfires are often caused by a bad spark or a faulty air-fuel mixture . If your engine misfires, the check engine light often comes on and error codes are stored.

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.

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.

Spark Plugs A rough engine idle, can be caused by, spark plugs or wires. Spark plugs use the electrical current; received from ignition coils to ignite the air/fuel mixture, within the combustion chamber. A plug that is damaged or installed incorrectly, can result in fuel being burned at an inconsistent rate.

What causes a car to idle at low compression?

Exhaust and Intake Valves can be a big problem if they are carboned up. This can cause lower compression as the valve might stick open. A rough engine idle can be caused by spark plugs or wires. Spark plugs use the electrical current received from ignition coils to ignite the air/fuel mixture within the combustion chamber.

What does it feel like when your car Idles?

When your car is experiencing a rough idle, your engine may chug, vibrate, or shake while it’s running. This will cause your overall driving experience to feel rough and you’ll likely be bouncing a little bit in your seat from it. When the engine idles, there will usually be a misfire that you can feel just from holding onto the steering wheel.

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.

What does a carburetor air leak sound like?

With the majority of air leaks around the carburetor and throttle body there will be a detectable hissing noise. It means air has been forced to enter a tight or restricted passage (breach) and a hissing or whistling sound results.

Why is my GMC Sierra running rough at idle?

These packs are fired by the engines computer at exactly the right time to provide the optimal ignition timing. If a coil pack goes bad, it’ll cause a misfire and rough idle condition. Really, your Sierra will be running rougher at any RPM, but a misfire will be most pronounced at idle.

Is it normal to have a rough engine idle?