Q: I changed spark plugs and wires & cleaned throttle body, car idles rough and gas mileage is changed does not backfire or anything

asked by on

I cleaned the throttle body with bottle body spray and changed the spark plugs and wires. vehicle starts fine drives okay but I noticed a hesitation during idle like a bump at periodic intervals, also seems to be burning a little more gas. Spark plugs were pre-set from the company (set 0.040) I did not check them prior to installing them in vehicle.

My car has 132000 miles.
My car has an automatic transmission.

A few different components could be causing your issue. Your symptoms sound at first like a spark issue. If a plug was tightened down too hard, the gap can become smaller than intended. This would decrease the power of the spark and lead to a misfire.

Due to the fact these were just changed, I would inspect them and verify the repair is holding. If the vehicle is having a strong enough misfire, it will likely set a diagnostic code. You should attempt to have your car scanned, and see if any sensors are showing a problem. Some codes will not trigger the Check Engine Light, but will still help narrow down the cylinder that is having an issue.

If you need help with getting this fixed, consider YourMechanic, as one of our mobile technicians can come to your home or office to diagnose your misfire condition and help you fix it accordingly.

Was this answer helpful?
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. I changed spark plugs and wires & cleaned throttle body, car idles rough and gas mileage is changed does not backfire or anything

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: No oil on dipstick and slightly lower oil pressure

Hello. If you are checking the oil at the dipstick and it is being added to the correct area then you more than likely have a serious internal sludge issue. If there is a lot of sludge then the oil...

Q: Car shakes and the check engine light is on

Hello. If you have misfire codes on all of these cylinders, then the problem is much more in-depth. Most of the time when this occurs on one side of the engine, it is because the timing belt is worn out...

Q: passenger tail light out

Hi there. If there is no power to only that wire, then most of the time the short is in the wiring to the trailer wiring or in the rear junction block. Both of these are common areas to have...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.