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engine idle

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How to Troubleshoot a Car Idling at a High Speed
Car idle speed increases or decreases if there are damaged fuses, idle control valve, throttle blades, ECM, or a vacuum leak.
Symptoms of a Bad or Failing Idle Control Valve
Common signs include irregular or unusually high idle speed, the Check Engine Light coming on, and stalling while idling.
Symptoms of a Bad or Failing Oxygen Sensor
Common signs of a faulty car oxygen sensor include the Check Engine Light coming on, bad gas mileage, and a rough idle.
Symptoms of a Bad or Failing Exhaust Gas Recirculation (EGR) Valve
Common signs include engine performance issues like decreased power and acceleration, rough idle, and the Check Engine Light coming on.
Symptoms of a Bad or Failing Throttle Body Temp Sensor
Common signs include poor engine performance, stalling, and broken electrical connections.
Symptoms of a Bad or Failing Air Cleaner Temperature Sensor
If your car is having trouble starting in the cold, the Check Engine Light comes on, or idle quality is poor, you may need to replace the ACT sensor.
Symptoms of a Bad or Failing Distributor O Ring
If your car has a distributor, common signs the o-ring must be replaced include oil leaks and engine performance issues.
Symptoms of a Bad or Failing Exhaust Gas Recirculation (EGR) Tube
Common signs include rough idle, rattling noises from the engine, and the Check Engine Light coming on.
Symptoms of a Bad or Failing Idler Pulley
Common signs include a damaged bearing or pulley, squealing from the engine area, and visibly worn pulleys.
Symptoms of a Bad or Failing Air Fuel Ratio Sensor
If you notice a decrease in fuel efficiency or engine power output, as well as a rough idle, you may have to replace any air-fuel ratio sensors.
How Long Does a Timing Chain Last?
A timing chain is a metal chain, as opposed to the timing belt which is made of rubber. The chain is located inside of the engine and needs to be lubricated by...
How Long Does a Top Dead Center (TDC) Sensor Last?
The top dead center (TDC) sensor is the point from which the firing order is determined and the ignition system measurements are taken. The measurements are normally defined as before...
How to Buy a Good Quality Idler Pulley
The idler pulley system drives a car’s alternator and is part of a belt and pulley system that also covers power steering, the air compressor, and other devices. The pulley is essential;...
How Long Does an Idler Pulley Last?
The drive belt that is on a car runs nearly all of the major components of the engine. Most of the newer cars on the market have a serpentine belt rather than...
How Long Does an Idle Control Valve Last?
Among the most important factors in having a smooth running car is a consistent idle speed. Having the incorrect idle speed can lead to a variety of different issues. There are...
How to Keep Your Car From Stalling
When driving a car, we expect it to get us from point A to point B without any issues. It can become unnerving to drive if your car stalls randomly when...
How to Check an Idle Air Control Valve
Idle air control (IAC) valves regulate the engine idle speed. Engine idle speed is the revolution speed of the engine when the throttle is inactive.

Related questions

Question
Low rpm idle
Since you had the battery disconnected the computer needs to relearn the idle again. I would recommend having the throttle body cleaned and then the throttle relearn process done so the idle can stabilize and be relearned by the computer....
Question
Revving noise in engine.
There are over 20 potential causes of surging but a mechanic would initially evaluate the EGR (exhaust gas recirculation) system, vacuum or air induction leaks, fuel supply and fuel pump control circuit, spark plug(s) and the ignition system, and fuel...
Question
If you just put a brand new tps in a 97 jeep grand cherokee and the idle is at 1000 rpms, would you consider that the sensor is bad? Thanks
Hi there. You can adjust the throttle plate on the throttle body or adjust the throttle position sensor. If making the adjustments has no effect on the engine idle, then there could be a vacuum leak or the Idle Air...
Question
Hey when the car idles it revs up and down by like 300 revs or so and also when the car is off it doesn't recognize its in park.
The issue is the transmission position sensor is not working properly and registering that the transmission is in drive, neutral, or reverse. Check to see if the transmission is going into park when the shifter is in park. If the...
Question
Code C342D
Hi there. Either the throttle position sensor (TPS) or the idle air control valve (IAC) is not working. Check the wiring to the TPS sensor and the IAC valve and see if they are plugged in and if there is...
Question
Car won't maintain an idle.
Hi there. Try turning on the ignition to the ’ON’ position 3 times with 30 seconds each time to see if the fuel system had air in the rail. This will help with the air in the system. When starting,...
Question
Periodically vehicle runs rough at idle.
Hi there. Most of the codes that are coming on are for a misfire on cylinder number 3. Check the spark plug and wire on cylinder 3 and see if you are getting a good spark. Then check the fuel...
Question
Revs go up when idle and vibrates
Without knowing the engine size and vehicle having this problem I would have to say that you have an engine vacuum leak in an intake gasket or seal. You should have the computer scanned for any lean codes then have...
Question
My SUV has rough idle 1996 Ford Explorer
Hi there - your problem codes and their description were proper guidance - you have an air leak in your engines intake system, and the idle air controller is unable to compensate for this problem While it may or may...
Question
Rough idle on cold starts
When the engine is cold, the engine coolant temperature sensor must be working properly to signal the PCM to enrich the mixture on cold start. If there is a fault with that sensor, you can experience rough idle idle as...
Question
Rpm's fluctuate, idles too high
Your car has an electrically operated throttle body to control the idle speed. If the sides of the throttle body get dirty, as they inevitably do, the throttle will not be able to close completely and will not be able...
Question
Check engine light is flashing and I have next to none acceleration.
When the engine light is flashing, that means that something is not functioning correctly that could damage the catalytic converter. I would recommend having the computer (ECM) checked for any codes to give you a starting place for diagnosing your...
Question
My Volkswagen Golf GTI is idling above 1000 revs and engine stalls
First you want to look for vacuum leaks. Any air that gets into the engine without going through proper channels can cause bad behavior like you describe. Look under the hood for broken or loose vacuum hoses or any large...
Question
Rough idle and sputtering off and on
Hello, and thank you for writing in. Considering the age and mileage of the vehicle, there could be a number of issues going on. At this point in its life, there are going to be critical components that will need...
Question
idle is low and engine light flashes when I drive.
Hello, and thank you for writing in. The vehicle may be having many types of problems. With a lack of power and a ticking sound, we must look at the level of the oil and the drive belt. Both can...
Question
Replaced IAC valve. Now when I start the car it idles around 1500 rpm in park and neutral. Runs great while in drive and idles at
After the IAC valve is replaced you will need to relearn the engine idle again. Disconnect the battery for a couple minutes and then restart the vehicle and warm the engine at 1500 rpm and then let idle for two...
Question
My Acura TL 1999 has a idling problem. It idles high to low. And it takes a while for the gears to switch when I'm reversing and in drive.
For the idle condition, check the (IAC) Idle Air Control Valve and see if its plugged up. You can take it off and clean it and then put it back on. If the idle continues to be irreratic, then the...
Question
Spring thaw starting issues 1988 Pontiac Trans Am
Hello - your symptoms suggest a problem with idle control mechanisms, most likely the idle air control valve, or a dirty or malfunctioning throttle body. Also possible are dirty/gummed up injectors as well. I recommend a stalling at idle inspection...
Question
High Idling - Just put in a new IAC Sensor
Hi there. Usually a high engine idle is caused by a vacuum leak. The first thing I would do is to check your SAAB engine to see if you have a vacuum line that is loose, split or has been...
Question
My car won't start up after sitting for awhile unless I apply gas. I don't know if it is my fuel pump relay or my fuel filter.
Sometimes the idle control valve will stick closed and with the throttle closed little to no air gets into the engine when trying to start the engine. You should have the throttle body and idle control valve cleaned to see...

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