I had my motor put in a different Buick rendezvous now it has a high idle?

I had my motor put in a different Buick rendezvous and now it has a very high idle

My car has 160000 miles.
My car has an automatic transmission.

Experienced mechanics share their insights in answering this question :
Unless the vehicle you placed it in was an exact interchange for the specific engine, the vehicle’s PCM might not be compatible which will cause all sorts of anomalies. PCM’s vary from year to year and are matched to the compliment of engine sensors and controls that the vehicle leaves the factory with. So, if it is not the same model year, that could account for the issue. If the engine is an exact interchange for the PCM you are using, note that in the majority of vehicles, engine idle speed is controlled by an idle control valve (ICV). A faulty or blown fuse in other electronically controlled systems can cause the IAC motor to malfunction, leading to a higher than normal engine idle speed. The ICV valve itself can malfunction due to excessive carbon buildup in the intake manifold. Other possible causes of a high idle include vacuum leaks, a malfunctioning throttle and, rarely, a PCM/ECM malfunction. With regard to vacuum leaks, on a fuel injected engine a vacuum leak will cause a high engine idle as the engine’s oxygen sensor detect the extra oxygen entering the engine through the vacuum leak. The newly lean (too much air relative to fuel) status will result in the engine’s computer pumping in additional fuel, resulting in an abnormally high idle. A malfunctioning throttle system can cause both a high idle as well as an engine stall. A dirty air intake or cracked air intake tube is often the culprit. If you desire that this high idle problem be diagnosed by a certified Mechanic, dispatched by YourMechanic right to your location, please request an engine idle speed diagnostic – high idle and the responding certified mechanic will get this taken care of for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

How to Identify and Fix Common car Problems ?

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

Malfunctioning Throttle: A malfunctioning throttle system can cause both a high or low idle as well as an engine stall. A dirty air intake or cracked air intake tube is often the culprit. Computer Malfunction: If the powertrain control module is malfunctioning, idle speed may be affected.
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.
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.
Vacuum Leak: On any engine, a vacuum leak will cause a high engine idle as the oxygen sensor detects lean operation and the engine computer then tries to compensate, which can result in abnormal idle. Malfunctioning Throttle: A malfunctioning throttle system can cause both a high or low idle as well as an engine stall.
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.
In order to increase the engine idle speed, tighten the screw clockwise. You can use a Phillips head screwdriver to turn the idle screw clockwise. Turn the screw once or twice to make minor adjustments in the idle speed, or three-four times to significantly increase the idle RPM.
The engine RPM drop when changing gears is often caused by a failed throttle position sensor (TPS). When in use, the cone of the TPS accumulates soot that prevents the correct rod movement. If a TPS works abnormally, the air-fuel mixture will not meet the requirements.
No, revving your engine while you`re in park is generally not bad. You can also rev it in neutral without hurting it—just be mindful of how much you`re revving your engine, and for how long.
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.
For regular cars, idle speed is typically between 600 and 1,000 rpm, just enough to keep the engine`s ancillary systems going, but not enough to move the car forward much.
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.
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.
Common causes of why a car feels sluggish when accelerating include dirty mass air flow sensor (MAF), faulty spark plugs, defective throttle position sensor, clogged catalytic converter, faulty oxygen sensor, clogged air filter, and fuel system malfunctioning.
What RPM should a car drive at when accelerating? When accelerating your vehicle, it is best to stay within a 2000-2500 RPM range. This will give you enough power to reach an acceptable speed level while also ensuring the engine stays within safe operating limits.
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).
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.
The idle problem may be a result of a dirty or faulty idle air control valve. The idle air control valve monitors the air intake as it is mixed with fuel prior to being injected into the engine at low speeds and at idle.
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.
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 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.
When you rev your engine, you place additional and unnecessary stress on your car and its engine. This is imperative when it`s cold outside—revving your engine before it has had time to warm up is especially damaging, as the engine`s oil hasn`t had sufficient time to circulate and properly lubricate your car.
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.
Disconnect the idle air adjustment valve by locating and disengaging the electronic connector that holds it to the throttle body. Turn the idle screw to adjust the idle—turn the screw to the left to increase the RPM or to the right to lower it.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

I had my motor put in a different Buick rendezvous now it has a high idle?
ANSWER : Unless the vehicle you placed it in was an exact interchange for the specific engine, the vehicle’s PCM might not be compatible which will cause all sorts of anomalies. PCM’s vary from year to year and are matched to the compliment of engine sensors and controls that the vehicle leaves the factory with. So, if it is not the same model year, that could account for the issue. If the engine is an exact interchange for the PCM you are using, note that in the majority of vehicles, engine idle speed is controlled by an idle control valve (ICV). A faulty or blown fuse in other electronically controlled systems can cause the IAC motor to malfunction, leading to a higher than normal engine idle speed. The ICV valve itself can malfunction due to excessive carbon buildup in the intake manifold. Other possible causes of a high idle include vacuum leaks, a malfunctioning throttle and, rarely, a PCM/ECM malfunction. With regard to vacuum leaks, on a fuel injected engine a vacuum leak will cause a high engine idle as the engine’s oxygen sensor detect the extra oxygen entering the engine through the vacuum leak. The newly lean (too much air relative to fuel) status will result in the engine’s computer pumping in additional fuel, resulting in an abnormally high idle. A malfunctioning throttle system can cause both a high idle as well as an engine stall. A dirty air intake or cracked air intake tube is often the culprit. If you desire that this high idle problem be diagnosed by a certified Mechanic, dispatched by YourMechanic right to your location, please request an engine idle speed diagnostic – high idle and the responding certified mechanic will get this taken care of for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

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.

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.

Pulled motor and put in a newer motor but can’t get motor mounts to line up ?
ANSWER : The first thing to do is to compare the motor mounts on old and new motor to make sure they are the same on each motor and swap them if they are not the same.

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.

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.

I was given an estimate of approximately $900 to replace the rear calipers on my 2004 Buick Rendezvous. I thought that was high
ANSWER : It depends on exactly what is included in the quote you were given. If the quote you were given is strictly limited to the calipers and does NOT include brake pads, rotors, hardware or other brake system work, then your quote is over priced by 20% or more. To obtain a competitive quote from YourMechanic, please click on "Get a Quote" at YourMechanic’s brake caliper replacement service page. If and once you accept the quote, a certified Mechanic, dispatched by YourMechanic will come right to your location and get this service taken care of for you and, of course, save you money. If you have further questions or concerns as you decide what to do, do not hesitate to re-contact YourMechanic because we want you to make the most of your repair dollars and help you get the best possible results.

Idle is running high when driven. I put it in neutral and it idles at 2300 rpms. Just had a cold air intake put in and throttle cleaned
ANSWER : Hi there. Assuming your vehicle has ETC (electronic throttle control), "drive-by-wire" problems can develop when cleaning is performed. Manually opening the throttle plate may have affected the close position. An idle relearn performed with a capable scanner may resolve the issue. If the Check Engine Light is on, this may help direct the diagnosis. A vacuum leak may also create a higher than expected idle. I recommend having the vehicle’s high idle diagnosed and repaired by a certified technician, such as one from YourMechanic.