car surges when idle or in park. rpm bounce. car has cut off, but cuts back on.
When I am parked or idle (stop light etc) I can feel my car shaking and surging. The RPM bounce. My car also cut out the other day, but cut back on after restarting it. I have had the water pump replaced, a new battery, a new thermostat, and some kind of pulley that was replaced when my car overheated. sorry don't know the exact name as I'm at work. what is wrong with my car? Need help!!!!!!!!!!
My car has 128000 miles.
My car has an automatic transmission.
Experienced mechanics share their insights in answering this question :
It sounds like your idle air control valve could be failing. The idle air control valve is responsible for maintaining the proper amount of air into the intake while the vehicle is slowing down to a stop and resuming idle speed. When this valve fails, it can cause the exact symptoms that you described. I would recommend having the idle air control valve inspected by a qualified professional to determine if it is performing properly. If the IAC valve has failed, I would recommend having it replaced at your earliest opportunity.
How to Identify and Fix Common car Problems ?
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Among the potential underlying causes are vacuum leaks, EGR system malfunctions, malfunctioning oxygen sensors, dirty fuel injectors, fuel pump malfunction, faulty spark plugs, a faulty mass airflow sensor, or a faulty throttle position sensor.
If an engine is not getting enough fuel (this is called “running lean”), due to fuel pressure (regulated by the fuel pump and regulator), restricted fuel injectors, a vacuum leak or really anything that throws off the fuel mixture going in to the engine, this can cause the surge.
Engine hunting and surging at idle is usually caused by a fuel delivery, air leak, or governor system problem. Cleaning/overhauling the carburettor, adjustment of the governor, and/or changing the air filer may be required.
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.
The most prevalent cause of vibration is problems with your wheels or tires. The potential problems include improper wheel and tire balance, uneven tire wear, separated tire tread, out of round tires, damaged wheels and even loose lug nuts.
Your tachometer needle will bounce up and down if your engine has a vacuum leak. The vacuum created in the combustion chamber is used as a power source, and, as such, it is routed through the engine to various locations using vacuum hoses. Over time, Collins Auto Care advises that these hoses can start to leak.
Throttle body issues: A throttle body controls the amount of air that flows in the car`s combustion system. A malfunction in the throttle body can cause uneven fuel supply, resulting in surging. Malfunctioning fuel injectors: Inadequate fuel supply through fuel injectors could lead to surging.
The problem may involve an annoying change (up/down) of engine speed while cruising at a steady pace, a low drop (or even cut-out) at idle or when approaching a stop, a wild high engine speed of several thousand rpm followed by a drop to near zero, etc.
your car surges and dies out: a faulty map sensor can cause engine rpm to fluctuate or surge, primarily at idle or low speeds. if you turn on the air conditioning or use the power steering when the happens, the engine can die out. it will usually restart, but this condition will worsen and can be dangerous.
Oxygen (O2) sensor
An oxygen sensor monitors and analyzes the amount of oxygen in a vehicle`s exhaust system after combustion. A dirty, damaged or malfunctioning O2 sensor (or sensors) affects the air/fuel mixture, causing the engine to idle rough.
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.
How to fix it? Cleaning or replacing the fuel filter and adding a fuel injector cleaning treatment to the fuel tank should take care of clogged fuel injectors. If the rough idle persists, it`s time to take your car to an auto repair shop.
While it may seem like a small problem on its own, rough idling is a sign that some part of your engine isn`t working properly. Over time, rough idling can result in poor gas mileage, starting issues and major engine problems.
Erratic engine idle can be caused by various factors, but the most common and likely cause is a dirty or malfunctioning Mass Air Flow (MAF) sensor. This is a device found in fuel-injected cars and measures air flow so that the appropriate amount of fuel can be injected.
While it may seem like a small problem on its own, rough idling is a sign that some part of your engine isn`t working properly. Over time, rough idling can result in poor gas mileage, starting issues and major engine problems.
Relevant Questions and Answers :
the most relevant questions and answers related to your specific issue
car surges when idle or in park. rpm bounce. car has cut off, but cuts back on.
ANSWER : It sounds like your idle air control valve could be failing. The idle air control valve is responsible for maintaining the proper amount of air into the intake while the vehicle is slowing down to a stop and resuming idle speed. When this valve fails, it can cause the exact symptoms that you described. I would recommend having the idle air control valve inspected by a qualified professional to determine if it is performing properly. If the IAC valve has failed, I would recommend having it replaced at your earliest opportunity.
Just put on new throttle body now when start car idles fine but as warms up idle starts surging and bouncing up and down
ANSWER : First you need to check all the air hoses and vacuum lines. Any air that enters the engine without passing through the throttle body will make it behave badly. Then I suggest you disconnect the battery for a few minutes and review the re-learn procedure for the car. It’s pretty intricate, and not following it exactly can lead to a failure. Failing that, I suggest you get professional help. You don’t want to just start replacing parts as that can get expensive very quickly.Your Mechanic can send a qualified technician to your home to check out your car and help you figure out what needs to be done next.
Car rpm bounce at idle
ANSWER : Hi There,
Your car has a small purge valve called a purge solenoid in the Evaporative Emissions system that controls the venting of fumes from the fuel tank as these fumes build up inside, particularly when you are refueling the car with gas. The EVAP system prevents fuel vapors from the fuel tank from escaping into the atmosphere. The EVAP system collects and temporarily stores the fuel vapors in the charcoal canister. The charcoal canister is filled with activated carbon pellets that can absorb the fuel vapors. When the engine is running, the fuel vapors are purged from the canister and burned in the engine. The vent control valve (solenoid) controls the flow of outside air in and out of the charcoal canister. The vent valve is controlled by the engine computer (PCM).
Your car has a small purge valve called a purge solenoid in the Evaporative Emissions system that controls the venting of fumes from the fuel tank as these fumes build up inside, particularly when you are refueling the car with gas. The EVAP system prevents fuel vapors from the fuel tank from escaping into the atmosphere. The EVAP system collects and temporarily stores the fuel vapors in the charcoal canister. The charcoal canister is filled with activated carbon pellets that can absorb the fuel vapors. When the engine is running, the fuel vapors are purged from the canister and burned in the engine. The vent control valve (solenoid) controls the flow of outside air in and out of the charcoal canister. The vent valve is controlled by the engine computer (PCM).
I think you are on the right track in terms of things to check. The RPM fluctuation is likely a result of the faulty purge valve. When there is a leak present in the EVAP system, this can cause the mass air flow sensor to read incorrectly causing the RPM fluctuation you describe. The code related to the O2 sensor being lean is also likely a result of the affect the problem described above relating to the mass air flow sensor due to an under fueling problem. I would suggest having an expert from YourMehcanic come to your location to take a look at your vehicle.
After driving awhile, when idling, RPM drops below 500 & car stalls. Happens rarely but RPM fluctuates, and drops suddenly.
ANSWER : If you are having a stalling problem then you may have a computer code stored in memory. I suggest having the computer scanned to see if there is any codes stored and diagnose them as needed. The intake hose and air filter should be inspected for leaks in the hoses and dirty or leaking air filters. If the air filter is dirty or leaking then have the mass air sensor cleaned. If you still need help, have a mechanic diagnose the stalling issue for you and let you know exactly what repairs should be done.
Idles between 500rpm and 1300 rpm. Main concern is low rpm. Belt or pulley chirping mainly at low rpm Drives perfect but Idles bad
ANSWER : Hello. From what you describe it would appear that your vehicle may have more than one issue.
Belt chirping is usually caused by a worn belt or tensioner. If either component wears out the belt may loosen and chirp when the engine is started, or cold.
The low rpm low quality idle can be caused by a few different things. I would look at the idle air control valve, as that is the component that maintains the vehicle idle, and at any vacuum hoses that may be cracked or damaged, and possibly leaking. This is more likely for older or high mileage vehicles.
If you’re unable to pinpoint the issue yourself, consider YourMechanic, as one of our mobile technicians will be able to come to your home or office to diagnose your starting issue firsthand and make the necessary repair to your car.
Got my rear main seal fixed, but my car keeps having a rough idle, cutting off & the Electronic Throttle Control Light is on.
ANSWER : It sounds like you may have a faulty electronic throttle control unit. The electronic throttle unit opens and closes the throttle blade based upon input from various engine control sensors, including the accelerator pedal. This unit also controls, among other things, the cruise control function as well. When this control unit fails, this may cause intermittent stalling issues and rough idle problems. This is usually repaired by removing and replacing the throtte control unit. I would suggest having an expert from YourMechanic come to your location to diagnose and inspect your vehicle at your earliest convenience.
I pulled into a parking spot and put my car into park, when I lifted my foot from the brake the car continues forward.
ANSWER : The vehicle transmission did not get back to the park position due to the shift cable came off of the transmission shift linkage. You will need to have a mechanic like one from YourMechanic come to you and check the shift cable connection at the transmission to see if the shift cable bushing broke and let the cable end disengage from the shift linkage. The shift cable may need replaced if the cable end bushing is not available. I recommend a mechanic check the shift cable and replace cable or repair cable end as parts allow.
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
ANSWER : 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 minutes and then put in gear with no accessories on and idle two minutes and then put a/c on and put blower on medium speed and let idle two minutes. The engine idle should be relearned now.
