Rough idle when warm? (Best solution)

  • It is because rough idle when warm can either be caused by one faulty component or through series of problems. However, it is easy to recognize the problem, as during rough idling either the engine would run at an irregular rate or it may have varying RPMs without your foot on the gas pedal.

What causes rough idle at low rpm?

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 an engine to stutter at idle?

Along with faulty spark plugs, a build-up of dirt and grime is the likely cause of cars stuttering when idle. A clogged filter or fuel injection system can starve your engine of fuel or oxygen, causing your car to judder and shake.

Can a bad air filter cause rough idle?

Poor Engine Performance Engine misfires, rough idling and hard starts can all be traced to a clogged engine air filter. The dirty air filter restricts the air supply to the engine causing unburned fuel to form a soot residue that accumulates on the spark plug.

Can dirty fuel injectors cause rough idle?

Dirty fuel injectors are only one of several engine problems that can result in rough idling and engine stalling. If you notice these issues in your car, come in for a Complete Vehicle Inspection. Our expert technicians will get to the bottom of the problem and recommend a fuel system cleaning if needed.

What are signs of a bad spark plug?

What are the signs your Spark Plugs are failing?

  • Engine has a rough idle. If your Spark Plugs are failing your engine will sound rough and jittery when running at idle.
  • Trouble starting. Car won’t start and you’re late for work… Flat battery?
  • Engine misfiring.
  • Engine surging.
  • High fuel consumption.
  • Lack of acceleration.

Can a low battery cause rough idle?

If it’s got a shorted cell in the battery it can cause rough idling, stalling, etc.

How do I make my engine idle smoother?

Using a carburetor cleaner is a simple step to help dissolve these carbon deposits and keep them clean in order to prevent or decrease a current rough idle. An engine which is operating properly should run smooth without any excess noise.

Can a clogged catalytic converter cause rough idle?

A clogged converter can cause rough idle, engine hesitation upon acceleration, weakened power, hard-starting and, in some cases, a no-start condition. This symptom can be diagnosed by using a vacuum gauge on the intake manifold, or an exhaust back-pressure pressure gauge before and after the converter.

Can bad oil cause rough idle?

The car idle is rough Another side effect of dirty oil can be a rough idle that feels like the engine is shaking the vehicle more than normal. The reason for this is there’s an increase in friction between the pistons, rings, and bearings.

Can spark plugs cause rough idle?

Rough idling When your spark plugs are performing as they should, your engine sounds smooth and steady. A fouled spark plug causes your engine to sound rough while idling. You might also feel the vehicle vibrating.

What are the signs of a dirty air filter?

8 Dirty Air Filter Symptoms: How to Know When to Clean Your Air

  • Air Filter Appears Dirty.
  • Decreasing Gas Mileage.
  • Your Engine Misses or Misfires.
  • Strange Engine Noises.
  • Check Engine Light Comes On.
  • Reduction in Horsepower.
  • Flames or Black Smoke from Exhaust Pipe.
  • Strong Fuel Smell.

Rough idle when warm

If your automobile starts OK when it is cold, but has a difficult time starting or running smoothly when it is warm, look into the following likely causes.

Read further

A Vacuum leak can cause rough idle when warm

Why would a vacuum leak cause a rough idle when the engine is warm, but not when the engine is cold? Simple. As mentioned above, when you start a cold engine, the computer commands a rich mixture and a high idle, so even a small vacuum leak has a minimal impact on the engine performance. Once the engine has warmed up and the computer has reduced the amount of fuel being used and the idle RPMs being used, a vacuum leak becomes much more noticeable. Because a vacuum leak is actually air entering the engine that hasn’t been detected by the computer, it commands the proper air/fuel mixture, but the leak causes that mixture to become excessively lean.

In addition, some vacuum leaks are caused by heat, which is particularly prevalent in plastic components.

Check for leaks in all of the vacuum hoses, the intake air duct, and the intake gasket.

Engine coolant temperature sensor can cause a rough idle when warm

Using the engine temperature, ambient air temperature, and the throttle position sensor as inputs, the computer calculates the optimal air/fuel combination. As an engine coolant temperature sensor ages, it is more likely to deliver inaccurate results. Testing the functionality of the coolant temperature sensor using a digital multimeter or utilizing live data from your scan tool are also options. Using a non-contact infrared thermometer, compare the data from the coolant temperature sensor to the actual engine temperature.

A stuck EGR valve can cause a rough idle

Only when the engine is running at a high RPM should exhaust gas recirculation take place. Rough idle will result if the EGR valve is leaking, which will be more noticeable while the engine is warm. Because the fuel mixture is rich and the RPMs are high, a leaky EGR may not have an impact on cold idle performance. It is necessary to inspect the EGR valve to ensure that it is functioning correctly.

Leaking fuel injectors can cause rough idle when warm

Fuel injectors that are leaking allow fuel to spill into the combustion chamber of the vehicle. On a cold start, this is usually not an issue because most of the gasoline has evaporated between the previous shut down and the cold start, preventing any complications. However, while the engine is hot, leaking gasoline might result in a prolonged crank and a difficult start, followed by a rough idle for a period of time.

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Faulty O2 sensor

When the engine is started from a cold start, the data from the oxygen sensor is ignored by the computer. This is due to the fact that oxygen sensors do not operate correctly until they have reached their maximum operating temperature. All current oxygen sensors feature a built-in warmer to reduce the amount of time between when they are first turned on and when they are completely active. Not only do the heaters reduce warm-up time, but they also continue to operate throughout the duration of the engine’s operation in order to prevent the sensors from cooling down while the vehicle is idling.

However, in some instances, the heater may fail without generating a code. When this occurs, the sensor sends erroneous data to the computer, leading in the incorrect air-fuel combination being produced. This erroneous data would manifest itself in your short and long term fuel trim measurements.

Worn spark plugs

When the air/fuel combination is rich and the RPMs are high, a worn spark plug has a far easier time igniting than when the air/fuel mixture is lean and the RPMs are low, indicating that the spark plug is worn.

A Wonky fuel pressure regulator can cause rough idle when warm

Once again, this issue may not manifest itself when the computer is cold since the computer orders a rich combination and a high idle when the computer is cold. If a defective fuel pressure regulator is present when the engine is warm, it can create a rough idle by leaning out the mixture as a result of low fuel pressure.

What wouldn’t cause a rough idle when warm

When the engine is warm, a fuel filter would not generate a rough idle. At cold start, when fuel demand is higher, a partially blocked fuel filter would create significantly more issues. The year 2020 is a leap year. Rick Muscoplat is a professional musician. Rick Muscoplat posted a blog entry on

Rough Idle When Warm: Troubleshooting The Engine Problem

When the car’s idle becomes erratic, it is difficult to determine the underlying problems. Because rough idle when warmcan be caused by a single broken component or by a succession of faults, it is important to understand how they work. However, it is quite simple to identify the problem since, during rough idling, either the engine would run at an erratic pace or the engine’s RPMs would change depending on how hard you pressed the gas pedal. Once noticeable indicators of rough idling appear, diagnose the issue as soon as possible to avoid further damage to the vehicle.

Beware If Your Car May Encounter This Problem

According to Car From Japan specialists, the most common makes of automobiles that have engine rough idle after warm up are as follows: Drivers of the Makes have had their cars repaired at garages for Rough Idle When Warm, despite the fact that the problem is not widespread.

How To Fix Rough Idle When Warm?

The most probable source of rough engine idle is one of the fundamental functioning components, such as direct fuel injectors, the PCV valve, the EGR valve, the oxygen sensors, vacuum leaks, the air filter, and spark plugs or wire, among others. Now, let’s repair the problem when the engine runs rough after it has been warmed up in succession, and then look at the root cause of the problem.

1. Collect Fault Component Data

To begin, if your vehicle is equipped with a universal scanner jack, connect the code scanner to the jack and begin collecting information from the damaged components of the system.

2. Analyze The Components

When the vehicle is in park or neutral, double-check that the emergency brake has been engaged as well. After that, thoroughly check all of the components to determine the root cause of the rough idle.

3. Check And Replace Spark Plug And Wires (If Needed)

Start the car’s engine by turning on the ignition and letting it run for a few minutes. While the engine is warmed up, check to see that the choke linkage has been deactivated. Finally, using insulated plug wire pliers, remove the wires from where they have been plugged in for safety. If the engine’s speed does not decrease during the procedure, it is a strong indication that a spark plug or wire is faulty. During the method After a problem with the spark plug or wires has been identified, turn off the engine and remove each plug with a socket from the engine.

If any of the components has a strong white or brown hue to it or seems moist, it should be replaced right away.

Once that is completed, check the plugs after re-installation and engine initiation to complete the solution to the problem of the car running fine until it is warmed. It is possible that the spark plugs and wires may need to be changed. Source: FreepikMORE INFORMATION:

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Testing the plug wires with pliers is now necessary (insulated). Place the end of the spark plug connector on the engine block in order to do this. There would be no spark if the cables were faulty in any way. As a result, consider replacing them as well.

4. Inspect PCV Valve

When the temperature rises, the next component to cause rough idle is the PCV Valve. It can be fixed by servicing the component and afterwards verifying that it is completely operational and free of contaminants.

5. Check EGR Valve

Next, the PCV Valve, which causes a rough idle when it becomes hot, is responsible for the rough idle. By servicing the component and afterwards verifying that it is fully working and clean, you may resolve the problem completely.

6. Check Air Filter

The dirt that has collected in the filter housing must be removed. If the dirt has caused the filters to become damaged, it may be necessary to replace them.

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7. Check Oxygen Sensor

Because oxygen sensors are a critical component of the emission control system, if the engine’s computer shows a fault code, it indicates that the sensor has failed. A digital multimeter and a code reader may be used to pinpoint the specific problem, and if the sensors have failed, the only option is to replace them completely.

8. Analyze Vacuum Leaks

If you hear a hissing sound coming from under the hood of your automobile, look for the cause of the current problem. If the engine light illuminates and a lean-mixture fault code is shown on the engine’s computer, look for the leaking component and repair it.

9. Test Direct Fuel Injectors

If direct fuel injectors are the source of the problem, they should be cleaned using a combination of strong solvents and high pressure. Another alternative to consider is the use of fuel system additives, which are designed to keep fuel injectors clean. Note: An additive, on the other hand, might occasionally produce a rough idle issue. When the car’s idle becomes erratic, it is difficult to determine the underlying problems. Because rough idle when warmcan be caused by a single broken component or by a succession of faults, it is important to understand how they work.

The Crux

Following the knowledge gained from understanding the techniques to solve the idle while warmproblem, anyone may now keep an eye on the state of their car. Later on, you may take it to a qualified technician for assistance in correcting the issue and learning some important maintenance suggestions for the future.

Rough Idle When Warm

On November 19, 2005, at 3:26 p.m. Date of joining: November 2005 Number of posts: 2 0 Likes have been received. 0 Likes 0 Dislikes 0 comments have been made. When it’s hot, it’s rough to idle. As you can see, I’m having a difficult time finding out what’s wrong with my truck. I have a 1998 Expedition with a 5.4-liter engine. A few weeks ago, the truck began to idle erratically, and the check engine light on. Now, while it’s cold, it starts up nicely and runs smoothly, but as soon as the engine gets warm, it idles rough and dies at every stop light until I put my foot on the pedal to keep it going.

  • I took it to Autozone, where the codes were examined and the P1071 and P1072 were identified as the cause.
  • I was informed to change my gasoline filter by the person at Autozone, but I’m not seeing it as the source of my problem.
  • 8:00 p.m.
  • It is possible that it is unclean, especially if you use a K N filter.
  • On November 20, 2005, at 12:11 p.m.
  • There has been a lot of discussion on this site about the IAC valve.
  • It was discovered that the O2 sensors on the driver’s side were the source of the problem.
  • I’m very certain I’ve read somewhere on this site that those codes are oxygen sensors.
  • Wishing you the best of luck On November 20, 2005, at 4:49 p.m., Date of joining: July 2005 Lithia Springs, Georgia is the location.
  • It is possible that the ECT sensor is not transmitting an accurate signal.

12:30 PM3112-15-201401:30 PM7.3L Power Stroke Diesel 2008 F150601-12-201403:02 PM DallasSuperCrew2004 – 2008 F150601-12-201403:02 PM wifebeaterhitman 1997-2006 ExpeditionNavigator1511-08-201205:16 PM 1997-2006 ExpeditionNavigator Domino1997-2006 ExpeditionNavigator307-03-200803:54 PM307-03-200803:54 PM307-03-200803:54 PM fordguyforlife3.84.2L V6610-21-200612:08 AM fordguyforlife3.84.2L V6610-21-200612:08 AM fordguyforlife3.84.2L V66


Engine Idle Is Rough When It Is Warm Outside

When I start my car in warm weather (now in North Dakota, temperatures range between the mid-50s and the mid-60s), the idle is really rough, and you can smell the fuel pouring into the engine. Finally, after perhaps thirty seconds or so, the idle will become smooth. I can switch off the car and restart it approximately thirty minutes later, and the vehicle will behave exactly the same way. The ECT is new, having been updated around two years ago, the spark plugs have been changed about a year ago, although they might be fouled now that the engine is running rich, and the IAC is also quite new.

  • When it gets 450, the vehicle bucks and attempts to stall.
  • Also, if I am driving at a low pace and crank the steering wheel to go into my garage, the engine can occasionally stall out and then restart itself.
  • About three years ago, I replaced the engine with a new General Motors Goodrich crate engine.
  • I do have an exhaust leak on both sides of the vehicle where the exhaust manifold links with the Y-pipe.
  • Despite the fact that I have tested for vacuum leaks and have not discovered any, my fuel efficiency is quite poor.
  • Please let me know if you can offer any assistance or have any recommendations for things I may try.
  • YesNo AT 12:47 p.m.

rough idle only when warm or restarting?

Crzykyman advised that you follow his suggestion. Investigate whether it is your air charge sensor, which is located on the rear of the supercharger tube. My car had been acting up to the point that I was ready to junk it, but after changing the air charge sensor, everything started working perfectly. crzykyman. What were the symptoms that prompted you to look into the ACS system? My 94SC auto idles perfectly till I shut it down. Then the rpm drops from around 900 to 550, and the engine shakes so much that it practically stalls.

  • I took the ACS out of storage this past weekend and cleaned it well.
  • Some sort of malfunction appears to be forcing the IAC to shut down.
  • All of the idle air it receives comes from the additional small amount I have provided by cracking the TB open and turning the idle air screw on the TB all the way out.
  • I changed the PC last week, but there was no difference.

Ed Springer90, Black XR7, Ed Springer90 5-speed: 70mm TB, Fresh Air Intake,’94 Supercharger, 5 percent SC Pulley, Raised SC Top, I/C Fan, UD Pulleys, 190 l/h Fuel Pump, 36 Injectors, Headers, Magnaflow Muffler (no cats) with stock resonators, 3:27 Gears, Ripper Shifter, 73mm CL MAF (Blue Tube), Magnacore Wires, NGK Iridium Plug 94 Red SC (Second Chance) The following components are included: 70mm throttle body, fresh air intake, stock 90 SC pulley, raised SC top, I/C fan, 190 l/h fuel pump, 38 injectors, headers, Raven Muffler (no cats) with stock resonators, 3:73 gears, 76mm CL MAF (gold tube), Magnacore wires, NGK Iridium plugs, Royal Purple Lubricants, TRANSGO Shift Kit, Pro-Torque

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Rough Idle when warm

I used some Mass Air Flow Sensor cleaning to clean the air flow sensor on my car. In addition, I brought some Throttle Body and Air Intake cleaner to the IAC for them to use. I was able to get rid of part of the carbon buildup on the throttle by cleaning it out. I also dismantled the IAC in order to expose the sensor magnet portion, in order to determine what it was. Because the bottom hose was free, I could insert my finger where the hose was while I sprayed cleaner down the square hole until the cleaner came out the top.

The car was difficult to start at first, but after going to three different places today (and turning the car off three times), it idles much better.

At the very least, I hope it continues to be nice.

The IAC valve requires mechanical agitation, which necessitated the removal of the IAC (first remove the TB, then release the four JIS screws and remove the IAC).


Rough Idle when warm.

February 13, 2005, 5:23 p.m. Thread Starter is a command that initiates a thread. Date of joining: February 2005 Location: San Francisco, California, United States Number of posts: 6 No likes have been received, and no likes have been given on any of the posts. When it’s hot, it’s rough to idle. Since a long time, I’ve been experiencing difficulties with my vehicle. There is no CEL light on, and my car idles erratically when it is heated. The beginning is satisfactory. After the automobile has gotten heated, it begins to boggle and, in some cases, die.

It isn’t the map sensor, because I tested the voltage on all three wires and they were all good.

What else possibly be the source of the problem?

February 13, 2005, 6:41 p.m.

Hello, I’m experiencing the same issue.

February 13, 2005, 6:59 p.m.

Location: Chesapeake, Virginia, United States The number of posts is 189Likes are 0Received zero likes on the number of posts is 0 Re: (jscblulu)Are these vehicles factory-fresh?

February 13, 2005, 7:57 p.m.

Date of joining: February 2005 Location: San Francisco, California, United States The number of posts is six.

The number of posts is zero.

There isn’t even a mod chip.

Honda-Tech MemberJoined on September 2, 2002 Lafayette, Louisiana, United States Number of posts: 5,493 In the past several days, I’ve received 0 likes on 0 postsfitv.

Honda-Tech MemberJoined on November 4, 2004 Florida is the location.

Re:(PrettyLude) To elaborate more on the FITV, if you pull your intake off looking inside you will see a hole to the left bottom area of the throttle body, with your engine cold, turn on the car, when you put your finger over it you should feel air.

then warm up the car until the fans come on.

if you do.problem.replace it.

Date of joining: February 2005 Location: San Francisco, California, United States Number of posts: 6 No likes have been received, and no likes have been given on any of the posts.

For example, when the car is warm and when I gas it it sounds like blowing bubbles through a straw in a glass of soda as opposed to just straight blowing through the straw.

Also, does the FITV affect the performance on the car?

BTW, my car has a hard time starting up after the temperature of the car goes up then back to cold.

Re:(DelH22Sol) The FITV only affects the idle of the car on warm-up.

Try unpluging your TPS and see if the stuttering goes away.

Then check your IACV by unplugging it and making sure the idle goes down a bit.

Another long-shot thing to check is the intake manifold gaskets.

02-16-2005, 08:50 PM Honda-Tech MemberJoin Date: Feb 2003Location: SF Posts: 728Likes: 0Received 0 Likeson0 Posts Re:(Hawkze 2.3) could it be an egr valve stuck open?

the p28 that your running wont have that cel.

makes sense.

02-16-2005, 10:48 PM Honda-Tech MemberJoin Date: Sep 2002Location: Lafayette, LA, USA Posts: 5,493Likes: 0Received 0 Likeson0 Post ssince your running a p28, why don’t you do completely away with the egr?

Date of joining: February 2005 Location: San Francisco, California, United States Number of posts: 6 Likes: 0Received 0 Likeson 0 comments have been made.

If I take off the EGR, there would be a hole.

02-18-2005, 07:14 PM Honda-Tech Member Join Date: Jan 2004 Location: Further down the spiral, TX, usa Posts: 10,629 Likes: 0Received 0 Likeson 0 PostsRe:(DelH22Sol) (DelH22Sol) 02-28-2005, 01:28 PM Thread Starter is a command that initiates a thread.

A friend of mine says it could be the shaft inside the distributer.

I’m planning on changing the distributer shaft to see if it would fix the problem.

02-28-2005, 01:33 PM Honda-Tech MemberJoin Date: Oct 2004Location: Boston, Ma, USA Posts: 478 Likes: 0Received 0 Likeson 0 PostsRe:(DelH22Sol) (DelH22Sol) It could be something as simple as spark plugs and wires, or a crap tank of gas.

Plus H22s run very rich from the factory which could contribute to the plugs fouling.

EDIT: Also check the Distributer, and the fact that you run 87 octane gas instead of the recommended 91 could be part of the problem too.

It happen to be the distributer cap.

I used my stock distributer and just changed the cap.


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