Idle too high. 1994 Chrysler New Yorker
My idle is too high in my car. It should be at 800 but is idling at 1250 rmps. I put in a new Idle Air Control valve. My Powertrain Control Module is clear, and my scan tool said there were no codes. The air conditioning is off and the car is warmed up. Do you know how I could get my car to idle where it should be?
Experienced mechanics share their insights in answering this question :
Hey there, thanks for writing in about your 1994 Chrysler New Yorker. Start your engine and let it idle in park for at least 5 minutes. Listen and check the engine for any vacuum leaks or inlet air tube leaks. Any vacuum leaks will result in a higher than normal idle. You may need to use a rubber hose to your ear to isolate any vacuum leak. You will hear a sucking sound when you find it. For help having this resolved, a professional from YourMechanic can come to your car’s location to inspect the high idle and let you know what repairs are needed.
How to Identify and Fix Common car Problems ?
Our sources include academic articles, blog posts, and personal essays from experienced mechanics :
Often this is a result of dirt buildup in the air intake. Other times it can be a problem with a cracked intake tube. If the IAC motor`s vacuum port is leaking, this can be another cause of high engine idling. The leak could be sourced at the seal, or more often, in one of the attached hoses.
If the PCM offers no hints, the best place to begin looking for problems is with the Idle Air Control Valve/Bypass Air Control (IACV/BAC). You can try cleaning it and see if that improves your idle speed. A throttle body cleaning is likely to cure the high idle speed as well.
The engine`s oxygen sensor will detect the extra oxygen entering the engine via the vacuum leak which will alert the engine`s computer that the exhaust is running lean, which will prompt the computer to pump in additional fuel, resulting in an abnormally high idle.
A few things I would check are the throttle body, the idle air control valve, and the vacuum hoses. A dirty throttle body or idle air control valve can cause the idle to fluctuate. I would also examine the condition of all of the vacuum hoses, any cracked or leaking hoses can cause the idle to fluctuate as well.
Your engine may have more RPMS due to any of the following: Transmission fluid is leaking. Transmission slips when changing gears because of a bad clutch. Speed sensor isn`t working, and the car can`t switch gears.
If your engine revs up as you press down on the gas but your vehicle doesn`t accelerate as much as you`d expect, you may be dealing with transmission slipping. If you`ve ever tried to accelerate on ice, where your engine revs but your vehicle goes nowhere, you know the feeling.
Improperly functioning spark plugs cause an uneven burn of fuel in the engine, resulting in fluctuating RPMs and a louder noise. You might also experience increased vibrations of your vehicle while sitting idle or while traveling at low speeds.
Problem Description
Bad throttle position sensors can cause high idle without causing the Check Engine Light to illuminate.
An idle air control valve, also called an idle air sensor control motor, is an electrically operated valve that controls the amount of air that bypasses the throttle plate in cars with a fuel injection system [source: Autozone]. This causes the idling speed of the engine to change as needed.
About high idle levels:
The car may be louder than normal, or you may feel shaking (in more severe cases). When you put your car into park or neutral , the engines idle control valve maintains a specific idle speed, allowing your car to use minimal engine amounts of fuel.
On a fuel injected motor, a vacuum leak can cause the engine`s RPM at idle to increase. In fact, it`s possible to double the idle speed if the leak is significant enough. When a vacuum leak is detected, the O2 sensors on the engine will detect extra oxygen is entering the intake manifold.
The idle speed should feel consistent without skipping or slipping. In most of today`s cars, an idle speed of 600 to 1000 RPMs is average. If your car is idling rough, though, it won`t feel smooth. The RPMs will jump up and down, for example, or they`ll fall below 600 RPM (or whatever is typical for your vehicle).
The absolute most stress on an engine occurs at high RPMs. The forces acting upon the rotating assembly are exponentially increased with RPM. That also increases the magnification of any oiling inconsistencies (as small as they may be nowadays), which can be deadly to engines.
When a cars rpm goes up and the car is not picking up speed, this usually means that there is a problem inside the transmission. The valve body, shift solenoids, and or clutches of the transmission probably had gone bad or are worn out to the point they are causing a transmission shifting issue.
Get bigger tires. Get a differential gear set with a lower ratio, and/or get a overdrive transmission or bolt on system. These are a the options to lower your revs at top speed, but know this. If you don`t know what you are doing, it can get expensive fast, and you might move your rpms out of your optimal powerband.
Run the engine for five minutes at half throttle to bring it to its operating temperature. Then, turn the idle mixture screw slowly clockwise until the engine begins to slow. Turn the screw in the opposite direction until the engine again begins to slow. Finally, turn the screw back to the midpoint.
With solenoid energized, open throttle slightly and plunger will extend. Release throttle and adjust to desired RPM by turning hex head on plunger counter-clockwise to increase RPM and clockwise to decrease. When solenoid is de- energized plunger will retract.
If the idle air control valve becomes dirty or malfunctions, it may allow too much air into the engine, resulting in a higher idle speed.
Wondering what RPM should a car drive at when on a highway? There is no single RPM that is considered “normal” when cruising on a highway. To reduce wear and tear to the engine and ensure you get maximum fuel efficiency, it`s best to stay in the 2000-3000 RPM range when driving on a highway at 60-70 mph.
Car engine rpm increases as you press the accelerator, as does power — at least to a point. An engine doesn`t necessarily produce its maximum power at its highest rpm. Engine specifications typically present the peak horsepower figure followed by the rpm at which it occurs, such as 252 hp at 5,600 rpm.
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.
The IAC valve is controlled by an input signal from the ECU as required by the engine management system, the duration and frequency of the ECU input signal determines how long and how far the IAC valve opens, hence the amount of air that is allowed to bypass the throttle plate.
Engine Idles Roughly: A rough idling engine could be caused by a failing camshaft position sensor. This issue is more evident when the engine is idling. Hesitation: Hesitation during acceleration is a common issue that you may experience with a bad camshaft sensor.
The Idle air control valve or the IAC valve controls your engine`s idle speed and is controlled by the engine`s onboard engine computer system. The IAC valve controls the amount of air circulating around the closed throttle plate. It has solenoid or a valve-operating coil which opens and closes to regulate airflow.
Relevant Questions and Answers :
the most relevant questions and answers related to your specific issue
Idle too high. 1994 Chrysler New Yorker
ANSWER : Hey there, thanks for writing in about your 1994 Chrysler New Yorker. Start your engine and let it idle in park for at least 5 minutes. Listen and check the engine for any vacuum leaks or inlet air tube leaks. Any vacuum leaks will result in a higher than normal idle. You may need to use a rubber hose to your ear to isolate any vacuum leak. You will hear a sucking sound when you find it. For help having this resolved, a professional from YourMechanic can come to your car’s location to inspect the high idle and let you know what repairs are needed.
Read Full Q/A … : Idle too high. 1994 Chrysler New Yorker
High Idle, stalls when a/c or defrost is turned on and dies completely after some rough idling. If turned back off car is fine.
ANSWER : Hi there. The fact you able to get the idle speed to drop by tapping the gas pedal, lead me to believe the high idle is due to a sticking accelerator cable. Another possibility could be, a faulty throttle body not allowing the throttle to return to the closed position. Proper diagnoses should be performed to avoid unnecessary repairs. I recommend having your vehicles high idle be diagnosed and repaired by a certified technician, such as one from YourMechanic.
Read Full Q/A … : Idle too high. 1994 Chrysler New Yorker
High idling, jumping while idling, idle air control valve code
ANSWER : Hi there. This can be caused by the issues that you mentioned or a number of other things. You need to make sure all of the connectors are making good contact. I would then need to know what codes are in the computer to know if this is a circuit issue or not. Most of the time, it is not the circuit but instead a vacuum leak.
If there is a vacuum leak, then the vehicle will act like this and the computer cannot control the idle. Most of the time it is a bad hose or an EGR valve that is stuck open. That is the most common cause for this. I typically remove the EGR to check it to feel the diaphragm on the bottom of it to see if it is moving correctly. If you need to have this repaired, consider YourMechanic, as a certified mechanic can come to your home or office to diagnose and repair your car’s idling issue.
Read Full Q/A … : Idle too high. 1994 Chrysler New Yorker
Wont idle unless idle is turned very high. New filter,rebuilt carb,new lines.
ANSWER : I would definitely agree that your idle issue (especially on an older engine) is most likely a vacuum pump problem. However, it could be as simple as a stuck float bowl in the carb or idle adjustment screw that is faulty. I would recommend first replace the vacuum pump and check all vacuum lines. You might want to also verify the idle adjustment is accurate
Read Full Q/A … : Idle too high. 1994 Chrysler New Yorker
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.
Read Full Q/A … : Idle too high. 1994 Chrysler New Yorker
cold rough idle and P0303 code , run great after clearing code and warming up,
ANSWER : Code P0303 suggests a misfire in cylinder #3. This can happen for many reasons such as a vacuum leak, weak fuel pump (pressure), bad ignition coil, low voltage to the fuel injectors (causing pulse problems) or a faulty mass air flow sensor, all of which can cause an imbalance in the air/fuel charge in that cylinder. Try checking to see if you are able to replicate the misfire and see if it happens more under load or at idle or if it is completely just intermittent. This may help to narrow down what types of components to check.
Read Full Q/A … : Idle too high. 1994 Chrysler New Yorker
It cranks doesn’t start new batteries, oil pressure switch new pmd, new injection pump. new alternator, new glow plugs.
ANSWER : Hello.
A crank but no start condition can be caused by many things. A few common causes are a faulty crank position sensor, or issues with the fuel system. The crank position sensor is used in the engine’s fuel calculations, and in some cases it’s failure will disable the engine.
It may also be possible that there is issues with the fuel system that are preventing the engine from running. If the fuel pump or injectors have an issue the engine may not run correctly, or at all. It may also be possible, for either case, that the issue may be wiring related.
I would start by trying to determine if the engine is getting fuel and then going from there. If you need assistance with these checks, consider YourMechanic, as one of our mobile technicians can come to you in order to diagnose your starting issue firsthand for an accurate repair.
Read Full Q/A … : Idle too high. 1994 Chrysler New Yorker
We have a new battery, new alternator, new coil pk, new master fuse and the car still won’t hold power.
ANSWER : Hi there. The only thing that I could think possible is causing your problem is that something may not have been correctly installed while your son was completing this maintenance. However, if your engine was difficult to start before this service, it’s possible there are different components that are damaged that simply didn’t resolve the issue. The only way of knowing what is going on with your Trailblazer would be to have one of our mobile mechanics in your area come to your location and complete a car is hard to start inspection.
Read Full Q/A … : Idle too high. 1994 Chrysler New Yorker
