Why the Car is Idling Rough & 10 Tips to Solve Rough Idle Causes-Part I

Posted by Candy Lai on

What is rough idle?
Why is car idling rough and car idling low?
How to slove rough engine idle?
What happens my car is rough idling?
Many different problems could result in rough idle causes for your car or truck, including: clogged air filter, bad air filter and dirty air filter.
Can a clogged air filter cause rough idle?


What message is your car trying to tell you via shaking?
Car shaking is a signal to show something wrong with vehicle.
There are 3 types of car shaking.
1. The car starts shaking.
2. The car is shaking during driving.
3. The car is shaking while idling.

Different circumtances has different causes.
Today, we're going to discuss the idle rough first.
If you're encountering your car starts shaking or drives shaking, stay tune, we'll discuss these 2 circumstances soon!

What's Idling?
So called idling, is you turn on the engine and let engine run without pedaling.
Normally it will maintain a 1,000 rpm low speed and with right amount of fuel and air, the speed will keep constant.
Which means, if vehicle starts to idle unsteadily, the engine speed will not be able to maintain.

Top-10 Reasons Cause Car Idle Rough & High

1. Failed Carburetor Problem 
Old model vehicles has carburetor to process fuel.
Very common symptom to indicate a malfunction carburetor is the excessive amount black exhaust smoke. 
You can use carburetor cleaner to remove carbon deposits and solve idling rough problem.

2. Dirty Clogged Fuel Injector
On the contary, new vehicles have fuel injector instead of carburetor.
If the injector is stuck, it can't deliver proper amount of fuel then will result in power loss or unsteady engine idle.
So, keep it clean to prevent clogging problem.

3.Spark Plug
This is the most easy way which car owners can check and install by ourselves at home.
First, remove the spark and check the appearance.
Different kind of excess deposits on the surface stands for different reasons to cause spark plug failed.
3.1. Ash deposits: It tells that the fuel you use is poor quality or you may have an oil leak.
3.2. Carbon deposits: It indicate the spark is not strong enough for the too-rich mixture.
3.3. Oil deposits: Most likely is the piston rings are wearing and the valves are leaking.
3.4. The gap: The proper gap, the distance between electrodes, can be checked with feeler gauge. Followed the correct gap which defined by the manufacturers.
Check above plug appearances to make sure spark plugs are in good condition.
You can also get the maintenance interval idea in your driver manual.

4. Ignition Coil
Likely as spark plug, if ignition coils malfunction, they cause misfire.
Check Engine Light (CEL) then be triggered and different error code will tell you what's going wrong.--> Changing Ignition Coils to fix Misfire Problem with code P0301


5. Air Filter
Air filter plays a role to make sure clean & proper amount air entering the engine.
It can keep dust and dirt away from the engine.
Regular change this folded paper element made filter can make sure the filter not clogged with dust.
Once the filter is clogged, the air will not be clean and the flow will not be enough for engine, rough idle then appears.
This air filter replacement can be DIY by removing the old one and switch it with a new one.
Yes, it is so simple as you read.

....To Be Continue to Part-II soon......


Read More:
<When to replace Ignition Coil and how much does it cost>

<Ignition Coil Symptoms of Saab 9-3 Bad Coil Packs & Tips to Find Out Broken One>

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