Inconsistent RPM. It is too high majority of the time

I have santro and is giving fast pickup with increase in rpm in normal run also I have checked and cleaned throatal body adjusted the rpm but still the problem exists kindly provide corrective measure to be taken

My car has 149000 miles.
My car has a manual transmission.

Experienced mechanics share their insights in answering this question :
Hi there. If a high idle is the concern a sticking idle air control valve or a vacuum leak could be the problem. Has anyone attempted an idle adjustment? If so, reset it back to the factory position. Listen around the engine compartment for a "hissing" or suction type noise as this will be an air leak into the intake and could cause a high idle is the check engine light on?

Check for codes that may be stored in the engine computer as there may be a current or pending code that could lead you in the right direction. An idle air control valve could be sticking or have contamination buildup in the valve that could be causing the erratic/high idle. Sometimes cleaning will correct the condition, but ultimately the valve needs to be replaced if this has happened.

I strongly suggest having a qualified technician perform an inspection to avoid replacing unnecessary parts. YourMechanic has several available technicians that can assist you with a car’s idling issue.

How to Identify and Fix Common car Problems ?

Our sources include academic articles, blog posts, and personal essays from experienced mechanics :

RPM fluctuation is a common issue for cars with faulty spark plugs as they fire the fuel with the pistons. If they wear out, your acceleration slows, and jerking and misfire start occurring, which, in combination, causes poor fuel economy and vibrations.
Replace the sensor with a compatible one and correctly install the crankshaft position sensor to ensure that the engine runs optimally and safely. A qualified technician can prevent further issues with RPM fluctuations while driving by installing the sensor correctly.
Worn-out spark plugs (these are the most likely cause for the issue) A defective idle air control (IAC) valve. A faulty sensor. Dirt or grime on your fuel injector.
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.
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.
If you notice a large delay between going into gear or between shifting gears where your engine is revving really high before it shifts, it may point to several problems with your transmission: Transmission Solenoid problems. Engine problems. Low or dirty fluid.
If the alternator is dying and the battery isn`t fully charged you can expect all kinds of weird electrical problems to happen. The alternator output will fluctuate with changing RPM.
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.
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.
If the throttle sensor or TPS is broken, your car can start to accelerate on its own. As you can guess, it results in higher RPM. Other than that, you may also experience misfires or will have trouble turning the engine on.
Symptoms of misfiring spark plugs include rough idling, uneven power when accelerating, and an increase in exhaust emissions.
The most common problem is a faulty fuse. In modern vehicles, engine idle speed is most often controlled by the idle air control (IAC) motor. This can be impacted by bad fuses in many different electronic systems in your car. Next, your high idling could be caused by a computer malfunction.
The most common cause of the shaking most often happens near your tires and rims. The tires and wheels connect your vehicle to the road, and if anything is a bit wonky, will notice. It may be something like a broken transmission or a broken control arm.
The alternator also provides power to your spark plugs. The spark plugs use this power to ignite the air and fuel that is found in the combustion chamber. If the alternator is going bad, it may not be sending enough power to the spark plugs and your engine will misfire.
No it can cause starting problems , Once the engine is started the alternator supplies voltage to all the electric devices so it won`t affect idle speed .
A malfunctioning TPS will cause your engine to run poorly. Generally the engine will idle fine but will have difficulty accelerating. This is because the computer isn`t telling the engine to inject as much fuel as is required, while at the same time airflow is increasing.
The Idle Air Control Valve is a critical component of your car`s engine. Its primary function is to control the airflow into the engine when the throttle is closed. If the IAC valve becomes dirty or faulty, it can cause the engine to idle erratically, resulting in fluctuating RPM.
The RPM gauge, or revolutions per minute gauge, is typically controlled by a sensor called a crankshaft position sensor.
Once the O2 sensor goes bad, your vehicle`s main computer may push too much fuel into the combustion chamber. This will make your engine surge and you feel as if you are driving a bucking bronco.
This can be caused by a defective instrument cluster or the wiring connections and wiring to the cluster. The cluster will need to be removed and wiring tested to see if an rpm signal is getting to the cluster. If signal is getting to cluster then check connections ar cluster and verify good contact.
Monitor RPMs when idle

If the needle is steady, this indicates your engine is running properly. If the needle drops by a few hundred or shoots above 1,000 RPM when the engine is warm, your engine may have a problem. You should have it checked by a professional.

Monitor RPMs when idle

If the needle is steady, this indicates your engine is running properly. If the needle drops by a few hundred or shoots above 1,000 RPM when the engine is warm, your engine may have a problem. You should have it checked by a professional.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

when i start my rav4(1997) the rpm goes high for about 5 min althought that wasnt occur before a period of time ,, what might be t
ANSWER : Hello, thank you for writing in. There are several causes for high idle after starting. The first thing to consider (although it has its limits), is that the engine does need more fuel when cold. This is why all cars have a higher idle after starting. Vacuum and a vacuum leak will have a huge effect on the RPMs. There are a few different tests you can do to find a leak if this is the case. Do a test that you can perform at home with the tools you have. Throttles and idle air control valves/solenoids are also largely responsible for the engine’s performance at idle. You will want to check these components next. It is a process of elimination to find what your issue may be. 2000 RPMs is too high for a starting idle, and there is likely a deeper issue going on.

Inconsistent RPM. It is too high majority of the time
ANSWER : Hi there. If a high idle is the concern a sticking idle air control valve or a vacuum leak could be the problem. Has anyone attempted an idle adjustment? If so, reset it back to the factory position. Listen around the engine compartment for a "hissing" or suction type noise as this will be an air leak into the intake and could cause a high idle is the check engine light on?

Check for codes that may be stored in the engine computer as there may be a current or pending code that could lead you in the right direction. An idle air control valve could be sticking or have contamination buildup in the valve that could be causing the erratic/high idle. Sometimes cleaning will correct the condition, but ultimately the valve needs to be replaced if this has happened.

I strongly suggest having a qualified technician perform an inspection to avoid replacing unnecessary parts. YourMechanic has several available technicians that can assist you with a car’s idling issue.

High RPM’s when pressing brake
ANSWER : Hi There,
There are 3 sources of signals that are involved in up and down shifting points the computer arrives at to direct transmission shifting.

The Idle Air Control Valve. The idle air control valve is a small valve on the engine’s intake system that reads the air intake as it comes into the motor. This is controlled by the car’s ECM which uses this information to make adjustments to the air/fuel ratio depending on various inputs such as outside air temperature, intake air temperature, load and various other things. As you accelerate, your car’s engine is receiving a much higher dose of fuel than when at idle and conversely, when you let off the gas pedal, there is a sudden change in this fuel supply as a result of your foot letting off the pedal.
The Throttle Position Sensor. The throttle position sensor monitors the throttle position of the throttle plate inside the throttle body in relation to your foot position on the gas pedal. Based upon the inputs from the sensor reading your foot’s position on the pedal, the ECU then makes the direction to supply more or less fuel to the motor. When this sensor is not working properly, this can cause intermittent responses when pressing the gas pedal.
VSS speed sensing. The transmission speed sensor is a magnetic sensor that provides this information, allowing the transmission to shift smoothly. The sensor counts the internal number of revolutions of the transmission and transmits that information to the transmission control unit, where the data is used to determine the rotational speed. As the rotation increases, the control unit directs the changing of gears. When this is not working properly, this may cause the transmission to shift erratically or in some cases not at all.

I would recommend having a professional from YourMechanic come to your location to diagnose and inspect your vehicle to determine what may be causing this.

At times my jeep will start fine and at times I have a hard time getting it to start. It seems like the wireless ignition node is
ANSWER : The recommended diagnostic to resolve this is a hard starting diagnostic. The work is performed by a certified mechanic right at your location. Among the first things the mechanic will check is whether required maintenance is up to date because old spark plugs, clogged fuel and air filters, and the like are potential causes of the hard starting you are describing. Other possible causes include a failing coolant temperature sensor, or bad connection to the sensor, problems with other sensors such as the cam and crankshaft position sensors, a defective fuel pump, and many other causes, all of which will be familiar to YourMechanic’s experts. With regard to the fuel pump, if the engine is not getting enough fuel it will be hard to start. If you request a hard starting diagnostic, YourMechanic will get this issue diagnosed and resolved for you.

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.

Timing chain positioning
ANSWER : This system is a bit complex. I can give you some instructions, but I highly recommend getting a hold of a repair manual or purchasing a yearly subscription for just your vehicle from AllData. It is only $25 for a years subscription from AllData.

There are two separate sets of marks on this system. One set is for aligning the timing chain to the camshaft gears and the intermediate shaft gear. There will be marks on the chain that raps around the crankshaft gear as well. These marks will not line up after you turn the motor over.The other marks are on the inside of the camshaft gears and align with the cylinder head parting line. If you were to draw a ling through the center of both camshaft gears, they should line up with that imaginary line.

The crankshaft key way should be aligned with the mating face of the main bearing cap. You can confirm it is in the correct position by verifying the number one piston is at top dead center. If you have removed the balance shaft timing chain, these marks really need a visual diagram to understand where they should be aligned. Without a diagram I am not very confident it can be explained very clearly.

This may be difficult to to follow, so again I highly recommend purchasing a repair manual in digital form or a book. If you feel this is over your head, I recommend the following inspection to help you out. Timing chain replacement

Good luck! I hope I was able to help you.

On cold start it take long time until it cutch 90 degrees and all that time keep cold/high rpm about 1200
ANSWER : There are many causes of hard starting but illustrative ones are a faulty engine coolant temperature switch (sensor), worn spark plugs, inadequate fuel delivery or pressure (clogged fuel filter), and contaminated or old gasoline. When the engine is cold, high (e.g., 1,200 RPM) RPM is normal. The engine speed should gradually decrease as the engine warms. If it doesn’t there is typically a problem in the air induction system. To resolve the issue that you are writing in about, please request a hard start diagnostic and the responding certified mechanic will get this resolved for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

need a way to retain the timing chain
ANSWER : The best way to approach this unfortunately is by using a timing chain tool retainer/holder tool. You may consider having an expert from YourMechanic come to your home replace the timing chain.