Q: Car runs rough after it heats up.

asked by on

I have replace everything on my car except the emc My car will start up normal. I can drive it on the highway with no problems once it heats up. I can stop at a red light and it runs so ruff it misses really bad. I can give her a little extra gas at the light and she will run fine with a little rattle in the engine and the rattle sounds like like a bearing. The A/c works perfect. Temperature gage works. Every thing works in the car. Other than that she's perfect. I have replaced wires sparks plugs o2 sensor and air filter. We even disconnected the tork converter. Just in case it was clogged. Every thing I have done to it changes nothing. I get 32 miles to the gallon of gas. The only thing that don't work on my car is the driver side door window won't roll down. Please help and thank you. I can afford to take her to the shop since everything has been replaced. Thanks

My car has 30000 miles.
My car has an automatic transmission.

Hi there. This sounds like there is a minor vacuum leak on the intake. Check the gaskets around the mounting surface of the intake. Check all vacuum lines coming off the intake and see if they are leaking or cracked. If there is no vacuum leaks, then the engine could have a burned valve making a cylinder misfire. Check compression on the cylinders and see if any of the cylinders have a lower compression than the others. If a cylinder is low on compression, then there is a good possibility that a valve is burned and the cylinder head needs repaired. If you need further assistance with your engine running rough at idle, then seek out a professional, such as one from Your Mechanic, to help you.

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

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!
  1. Home
  2. Questions
  3. Car runs rough after it heats up.

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: Broken thermostat housing

A cracked thermostat housing can definitely cause the coolant temperature sensor to produce false readings due to the fluctuation in temperature and leaking coolant. I would suggest having a professional from YourMechanic come to your location to diagnose and inspect...

Q: Valve guide seals 2006 BMW 750i

Hello - unfortunately, this is not a service YourMechanic.com can offer at this time. Thanks for thinking of us though!

Q: Switched to synthetic oil, now I smell burning oil, possibly engine running hotter

Hi, thanks for writing in. Synthetic oil is typically a little bit thinner than conventional oil. Often times when a vehicle is switch from conventional to synthetic this can cause oil leaks or burning oil. I would recommend changing your...

Related articles

Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
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...
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.