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.

A spark plug comprises three main parts: the housing, insulator, and electrodes.

Strictly speaking it is not safe to drive your car if the engine is misfiring. If you notice the intermittent loss of power or poor acceleration, you should get to a mechanic as soon as possible. The longer you drive with a misfiring engine the more likely it is that you’ll cause further damage to the engine.

While a shaky idling car can certainly feel like an earth-rumbling tremor, it can also indicate a problem with the engine. One common cause of shaking while idling can be loose engine mounts. Alternatively, a car that shakes when idle may have faulty fuel injectors, worn-out spark plugs, or a bad timing belt.

Motor Mount. You could have a damaged or broken motor mount. Motor mounts are the things that attach the engine to your vehicle’s frame. That sounds serious because it is, and damage to one or more of the motor mounts can allow the engine to vibrate and move around when you press the gas pedal.

Rough idle caused by spark plugs, spark plug wires or ignition coil problems. If you have a rough idle that is caused by either the spark plugs, spark plug wires or ignition coil, you will also feel it when accelerating. If these parts are bad enough to cause a miss at idle, it will continue to miss while driving.

Shaking or vibration may be caused by many different things such as faulty spark plugs, poor fuel pressure or misfires. Other things such as a faulty idle air control valve may cause the engine idle to drop below the normal idling RPM which may also cause the motor to shake or vibrate more than normal.

Hi There, It sounds like you may have a dirty or failing idle air control valve causing your engine idle to fluctuate. When this happens, the job of the idle air control valve is to bring this deceleration down to a slow and smooth idle rather than suddenly cutting off the fuel supply causing the motor to die.

Common signs include irregular or unusually high idle speed, the Check Engine Light coming on, and stalling while idling.

Reset the IAC valve pintle position by performing the following: Depress the accelerator pedal slightly. Start the engine and run for 5 seconds. Turn the ignition switch to the OFF position for 10 seconds. Restart the engine and check for proper idle operation.

if you mean bypassing the coolant lines that run to the TB… yes you can totally do this. I’ve always done this to my b-series swaps in my own car. It didn’t affect idle or anything.

The replacement cost of an idle control valve is anywhere from $120 to $500. The cost of the parts alone will be between $70 and $400+, depending on the make and model of your vehicle. The labor cost should only be around $50 to $100 because it doesn’t take that long to remove and replace the old idle control valve.