Q: Q: Rough idle and engine stalls out.

asked by on

engine start when sparying intake clearing in air intake manifold. spark plugs are filed out ,tips are black

My car has 190000 miles.
My car has an automatic transmission.

This suggests a rich fuel condition as evidenced by the black fouled out spark plugs. This can happen for a couple of reasons such as faulty or leaking fuel injectors, or a faulty or dirty idle air control valve.

The idle air control valve reads the air intake as it is mixed with fuel prior to being injected into the engine at low speeds and at idle. As this valve is controlled by the vehicle’s computer, it will adjust idle speed based upon other measurements such as engine temperature, intake air temperature and electrical system load or voltage. When you accelerate, the engine RPM increases, and as you let off the gas, the RPM slowly returns to the normal idling speed. When the engine RPM drops below the normal range of 750-800 RPM (for most cars), this often times will cause the engine to stall indicating a dirty or faulty idle air control valve. I would recommend having an expert from YourMechanic come to your location to diagnose and repair your idle air control valve.

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. Q: Rough idle and engine stalls out.

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: Having trouble opening hood

There is a release mechanism under the hood, but it may be difficult to locate and manipulate. Often, the mechanism needs to be lubricated once it does release. I highly suggest having a trained mechanic, like the ones we have...

Q: Truck dies when not on the throttle.

Hello. A few things I would check are the timing, the idle air control valve, and the condition of the vacuum hoses. Retarded ignition timing can sometimes cause low throttle issues, and can definitely cause stalling. The idle air control...

Q: Won't start after putting in new alternator, battery, starter and fuses.

Hi there. Check the battery cables and make sure that they are hooked up properly. Look to see if there is an issue with a loose ground on the fuse box. When smoke comes from the battery cables, that usually...

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...
How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
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...