Q: It has a slight rough idle

asked by on

Felt like a misfire, so I replaced plugs and wires. The issue was still there with idle dropping a little low after giving it gas and just a rough in general. Took it to a friend with a scanner because it had a check engine light on and the code was for cylinder #8 misfire. I swapped the coil to the #2 cylinder and then took it back to read but no CEL on. I did a vacuum test and it was at 18in hg and went to 21in hg at 2000 rpm. I took PCM fuse out turned key to start until I heard two chimes and then reinstalled. No CEL on and it drives great but when it's stopped, the idle is slightly rough. It's pretty minor, but it's not smooth like it was before.

My car has 11000 miles.
My car has an automatic transmission.

You may have fixed the misfire, but the rough idle may be due to clogged injectors and carbon build up on the valves. Try cleaning injectors and throttle body and intake system and see if problem improves. If you the problem still persists, you may want to enlist the help of a certified mechanic, such as one from YourMechanic, to come to your car and inspect the rough idle.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1,000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. It has a slight rough idle

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

Get a quote

What others are asking

Q: My check engine light came on, changed O2 sensor. Check engine light was still on, then three days later went off.

Hi There, The last diagnosis is correct in that the sensor replaced caused the check engine light to turn off. In some cases they do not always turn off immediately and take a bit of driving for the computer to...

Q: Rough idling, delayed shifting on a '07 Audi

Let me tell you. You've got a nine-year-old TDI Audi, and that's when they often turn into serious money pits. If it's changing gears too late, odds are that the transmission is starting to go bad. This could be a...

Q: door locks keep chatering when i lock them 2000 cadillac esclade

Hi Brownie. Typically when the door locks continually "fire" (meaning open and close frequently), it's due to a relay that is open and not completing the circuit. In some cases, an exposed wire will cause this to occur, while in...

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...