Q: Car misses and has a rough idle - 2001 Saturn L100

asked by on September 09, 2016

My car has been missing and has a rough idle. I changed the plugs and also put in some expensive dry gas x2. Even though this is a Saturn, I had purchased it at Kia dealership, so I went to them. They said I had installed the wrong plugs and they replaced with the correct ones. When I’m driving at highway speeds, the car still misses.

I took it to the Saturn dealer and they reported that they had found the problem to be the ignition coil and performed the repair. The missing problem seems to be solved; however, my car still rough idles. What can I do to solve this rough idle?

Ignition Coil Replacement $132.12 - $587.62 Get a Quote
Spark Plugs Replacement $113.11 - $716.47 Get a Quote
Car idle is rough Inspection $94.99 - $114.99 Get a Quote

Hello. There are several things that could be causing your rough idle condition and therefore there are multiple possible solutions. Carbon buildup inside the intake manifold and valve train is a big cause of rough idle. This can usually be resolved by running a fuel system cleaner through your engine.

The wiring to the ignition coil could be damaged causing the rough idle you are experiencing. It is also possible that when the spark plugs were replaced, they were not gapped correctly which can also cause a rough idle.

I would recommend taking your vehicle back to the place that inspected the misfire issue and explain to them that you are still experiencing a rough idle and ask them to take a second look. You may be fortunate enough to have the issue resolved under warranty and at no cost to you. If you would rather have this looked at elsewhere, a certified professional from YourMechanic can come to your home or office to diagnose the rough idle and have this issue corrected.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing


Experienced Mechanic?

Earn up to $70/hr

What others are asking

Car not accelerating and sputtering
There are many reasons why your car will not accelerate. Is the Check Engine Light on? There could be a faulty sensor that is confusing the computer in your vehicle. When this happens your car will not run correctly. I...
My car wont start it says something about the shifter and just clicks
There is a technical bulletin out for your 2015 Dodge Charger to reprogram the transmission control module to address this problem specifically. If you can't get it to crank (https://www.yourmechanic.com/services/car-is-not-starting-inspection), you will need to have the vehicle towed to the...
The OEM tinted windows that came with my 2015 CR-V, is the tinting on the inside or the outside of the glass?
Factory tinting is on the inside of the glass (https://www.yourmechanic.com/article/how-to-clean-windows-on-a-car-by-olivia-marsh). Generally, you shouldn't use any harsh chemicals on any glass or it may etch the glass and make it unclear or cloudy. If you choose to move forward with the...
Engine light keeps coming on after I reset it
Hi, thanks for your question. You will need to have the computer system scanned to see what code is stored in the computer and have it diagnosed. The code may be something from the previous repairs or something new. If...
The car stalled out and the battery and oil light came on
When a car has that many miles on it, it could be just about anything. The temptation is to go shooting in the dark and just start replacing parts until the car works again. That method can get very expensive,...
Doesn't start in the morning when the engine is cold. What's the problem? 2000 Dodge Van Ram 2500
Hi there. This can be caused by a number of things. Most of the time, it is necessary to check for fuel and spark when this occurs. This will let me know where to start with the diagnostics. Most of...
smoke/steam coming form dipstick 2009 VW GTI Turbo
Hello - it is normal to have a small amount of "fumes (https://www.yourmechanic.com/article/why-do-some-cars-have-really-smelly-exhaust-fumes)" exit the dipstick when it is pulled. The crankcase, is after all, a pretty violent place - oil and extreme temperatures combined with rotating hot metal. If...
I have a oil leak and now my car is shaking and cutting off.
Your oil leak may be unrelated to the vibrating or shaking, but suggests you may have a failing gasket somewhere. Gaskets can fail over time due to excessive heat and will eventually shrink causing them to fail and leak. I...
I got 97 ford f150 with 4.6 v8 and I was wondering if I could swap my 4.6l with a 91 5.0 s.h.o motor
You would need to do some major modifications to vehicle to do this swap. I would not recommend do the swap. The 1991 5.0 had less horsepower than the 4.6. You would be better off replacing the 4.6 1997 with...

Related articles

What Does a Spark Plug Do?
Your Your ignition system is pretty complex, and there are a number of important components that must work with one another to crank the engine and then keep it running. Your spark plugs are among the most important of these,...
Is it Safe to Drive With a Misfiring Cylinder?
An engine misfire can be caused by bad spark plugs or imbalanced air/fuel mixture. Driving with a misfire isn't safe and can damage your engine.
How to Find Top Dead Center
There There are many reasons why you might need to find an engine’s top dead center. Top dead center is the point when the piston of the number one cylinder in an engine is at its highest point, and on...