I have an issue with my Tahoe its idling rough the hand stays on 500 rpms but you can hear it in the engine

I have a 2003 Chevy Tahoe with 5.3L flex fuel. It's idling rough but the rpm hand stays on 500 rpms but you can hear it in the engine it will idle fine for a minute but then it will idle weird for about 30 seconds then go back. When I put my hand at the end of the exhaust pipe it blows out barely. Also my vapor canister surge soleniod has a vaccum going to it and a plug I checked the power to it and it has power but when I pull the vaccum line off of the vapor canister purge soleniod it is not sucking in air through the line at all so what do I need to do? Also it says misfire on cylinder
Experienced mechanics share their insights in answering this question :
It would appear you have already attempted to perform all of the normal repairs to fix this issue. Due to the high number of repairs made, you may want to start by retracing your steps and confirming that all the repairs are holding and functioning well. With that being said, one of the only aspects it appears you haven’t considered would be air.

Are your oxygen sensor working correctly? Have you looked at things as simple as the air filter and mass airflow sensor? Any one of these components can be sending bad signals to your computer and causing issues. The misfire is the reason you are experiencing bad gas mileage. Its most likely the reason you are having rough idling as well.

How to Identify and Fix Common car Problems ?

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The most common reasons a Chevrolet Tahoe has rough idle are a vacuum leak, an issue with the spark plugs, or a problem with the ignition coil. Search our network of RepairPal Certified shops near you to speak with a technician about your issue.
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.
Typically, the idle speed will be set at a value in the range of 600 to 800 RPM, but the exact value will depend on the number of engine cylinders and whether the vehicle is equipped with a manual or automatic transmission.
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.
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.
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.

One of the main reasons why your vehicle could be vibrating at idle could be due to worn out spark plugs. When a vehicle`s spark plug is faulty, it can interfere with the air-fuel ratio leading to improperly firing cylinders, resulting in a misfire while idling. Replacing your spark plugs will solve this problem.
About 600 to 650 rpm.
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).
Oil changes keep your car engine running smoothly. Rough idling, slow acceleration, and engine noises mean you need to replace your car oil.
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.
Oil changes keep your car engine running smoothly. Rough idling, slow acceleration, and engine noises mean you need to replace your car oil.
Fuel related misfires can be caused by many different things such as low fuel pressure, faulty or dirty fuel injectors, a faulty O2 sensor, a dirty or failing mass air-flow sensor, a faulty or dirty idle air control valve or a vacuum or intake leak.
The only way an exhaust leak can cause a rough idle is if the leak was in a place where it could enter the air intake system.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

I have an issue with my Tahoe its idling rough the hand stays on 500 rpms but you can hear it in the engine
ANSWER : It would appear you have already attempted to perform all of the normal repairs to fix this issue. Due to the high number of repairs made, you may want to start by retracing your steps and confirming that all the repairs are holding and functioning well. With that being said, one of the only aspects it appears you haven’t considered would be air.

Are your oxygen sensor working correctly? Have you looked at things as simple as the air filter and mass airflow sensor? Any one of these components can be sending bad signals to your computer and causing issues. The misfire is the reason you are experiencing bad gas mileage. Its most likely the reason you are having rough idling as well.

Engine idles rough and jumps between 500 and 1200RPM when shift from Drive to Reverse; Check engine light on
ANSWER : You may have a couple of separate issues:

The flashing Check Engine Light under heavy load is most likely an ignition system misfire. This could be something like a coil pack or worn spark plugs. These engines are known for going through coil packs so that would be my first guess.
The rough idle could be related, but it sounds more like a vacuum leak or possibly a faulty idle air control valve (IAC).

The first step is to retrieve the diagnostic trouble codes for your Check Engine Light which serve as a starting point for any further diagnosis. I suggest you have a trained professional, such as one from YourMechanic, diagnose your vehicle firsthand.

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.

My 2003 Mazda Tribute stalls in gear, no power, rough idle, not the plugs, oil fouled black, clean maf and idle air valve
ANSWER : Hello. I would start by scanning the vehicle for codes and checking to see if all of the sensors are reading correctly. If everything looks good then chances are it needs a new computer. I have seen the computers fail on these vehicles over and over again causing the ignition circuits to not work correctly which causes the vehicle to run just like this. If you need to have this looked at, consider YourMechanic, as a certified mechanic can come to you to [diagnose why the vehicle is running like this] https://www.yourmechanic.com/services/car-idle-is-rough-inspection

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.

Rough idle, fluctuating rpms, stalling
ANSWER : Hello, thank you for writing in. The vehicle is struggling to keep up with all of the different accessories when the engine is idling. This is typically due to an issue with the air intake, fuel intake, or the sensors that monitor and control them. Start by having the vehicle scanned for codes at your local automotive parts store, or by a different technician. If no codes are present, attempt to clean the throttle body, idle air control valve, and the throttle position sensor. If there are codes present, then you can use them to point you to the issue at hand, and take corrective action from there. For more help with diagnostics or resolving the issue, contact our service department to schedule an appointment.

Skipping engine, rough idle, shuts off during slow down & idle, overheating, white smoke from exhaust
ANSWER : Hi There,
It sounds like you may have a couple of separate issues going on here. Overheating can be caused by a number of things such as low coolant levels, a faulty thermostat, a clogged radiator or a failing coolant fan switch. As you may know the coolant fan switch helps to maintain the proper coolant temperature by turning on and off at specific temperature thresholds. When this switch is not working properly, this can cause the fans to come on intermittently, all the time or sometimes not at all. When this happens you will notice a temperature spike and drop occasionally as the fan comes on and off. When your thermostat is not working properly or is stuck closed, this will not allow the coolant to properly circulate through the engine, which may cause the engine temperature to fluctuate erratically or in some cases just remain hot. You may also have a water pump that is beginning to fail. Water pumps often times will begin to produce a bit of a whining sound when they are starting to fail. A common problem also associated with this is the water pump may begin to leak around the water pump shaft due to the seal being damaged. In addition to leaking around the pump, you may have a leak elsewhere in the cooling system coming from one of the hoses going to or from the radiator.

The rough idle and shutting off at slow speeds may be caused by 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. This valve is controlled by the vehicle’s computer and will adjust idle speed based upon other measurements such as engine temperature, intake air temperature and electrical system load or voltage. This is also an important function when starting the motor as it allows the motor to run and idle on it’s own once the motor fires. When you accelerate, the engine RPM increases, and as you let off the gas, the RPM slowly returns to the normal idling speed with the help of the idle air control valve making the transition from a higher RPM back down to idle speed while adjusting the air/fuel ratio constantly to allow this to happen smoothly. When the engine RPM drops below the normal range of about ~800 RPM, this often times will cause the engine to stall indicating a dirty or faulty idle air control valve. I would recommend having an expert from YourMechanic come to your location to diagnose and inspect your vehicle.

The car idles rough and is shooting out codes p0017, p0016.
ANSWER : Hello. This is a common problem with the variable valve timing solenoid on this engine. I have changed quite a few of these due to failure. I always start by checking the codes and testing the solenoids and the connectors as some of the time the connectors fail and have poor connections. There have been a few times that I have seen these codes due to low oil or the wrong oil and from the camshaft actuators failing, but most of the time it is due to the solenoids. If you are planning on having this fixed, consider YourMechanic, as a certified mechanic can come to your home or office to diagnose and repair the rough idling issue for you.