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Car stays running when I shut the key off Inspection Service

We’ve all heard a car continuing to run after the ignition key has been turned off, and it usually sounds pretty bad, with all kinds of clonking and coughing noises. These days, though, you’re more likely to hear this in the movies, when sound-effects staff is trying to show the viewers what a clunker this particular actor is driving. Modern cars are seldom afflicted with this particular problem.

The phenomenon often called “dieseling” is caused by a condition known as pre-ignition, where hot spots in the engine’s combustion chamber fire the compressed fuel mixture without needing a spark. This syndrome can also be present when the car is running under load, producing a characteristic – and potentially damaging – pinging sound.

What is actually happening is the fuel charge exploding all at once instead of burning across a moving flame front away from the spark that normally initiates combustion. Also known as detonation, the sudden explosion is often caused by the use of a too-low octane-rated fuel.

If this is happening to your car, it’s probably an old one with carburetors. New models all use electronic fuel injection, which shuts down when the key is switched off. Without fuel going to the cylinders, there can be no running on. Carburetors, however, will continue to supply fuel as long as the engine is turning over.

Because this phenomenon often occurs in older cars with a higher build up of carbon deposits in the engine, you may need to use a higher octane fuel than was originally specified. If this fails to quell the running-on mischief, then a tune up and possible replacement of spark plugs with a colder heat range may be called for.

Replacing your intake side valve stem seals may sometimes correct this issue as well.

Common reasons for this to happen:

  • Ignition timing is off
  • Broken lock cylinder
  • Bad intake side valve stem
  • Bad spark plugs

What to expect:

A top-rated mobile mechanic will come to your home or office to determine the source and cause of the running-on issue, and will then provide a detailed inspection report that includes the scope and cost of the necessary repairs.

How important is this service?

A running-on car is not only a waste of energy and fuel, it also presents a potentially dangerous situation. Book a mechanic to diagnose the issue as soon as possible.

Fast and easy Car stays running when I shut the key off Inspection service at your home or office.


Recent Car stays running when I shut the key off Inspection reviews

Excellent Rating

(4)

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Gustavo

20 years of experience
75 reviews
Gustavo
20 years of experience
Buick LaCrosse V6-3.8L - Car stays running when I shut the key off - San Antonio, Texas
Gustavo was very courteous and helpful. Enjoyed meeting him and appreciate his evaluation of my car.

Peter

43 years of experience
1321 reviews
Peter
43 years of experience
Lincoln Town Car V8-4.6L - Car stays running when I shut the key off Inspection - Chandler, Arizona
One and only unknown company in my 29 plus years in arizona that did not mislead or try to sell me on something that wasn't wrong. Honest and upfront. Thank you for sending Peter.

Terry

26 years of experience
326 reviews
Terry
26 years of experience
Buick Century V6-3.3L - Car stays running when I shut the key off - Tempe, Arizona
Terry showed up on time. He was friendly and professional. Inspected and determined repair that was needed. Unfortunately parts house didn't have part in stock(the car is a '91), had to be ordered so could not complete the repair.

Mark

41 years of experience
10 reviews
Mark
41 years of experience
Acura MDX V6-3.5L - Car stays running when I shut the key off - Durham, North Carolina
He's very friendly and did good work!

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