Car shakes when idling and shuts off as soon as I hit the gas pedal. Everything else works fine. I have tried to see if it would throw a code, but absolutely no luck there.
My car has 155000 miles.
My car has an automatic transmission.
The engine should be scoped to evaluate the secondary firing patterns. That will provide an important clue. Apart from mechanical possibilities such as a blocked exhaust and/or loss of compression, what you are describing is due to an ignition, fuel system, or air induction fault. There are lots of possibilities and so what you have will simply have to be diagnosed. Just as a for instance (but, again, there are many possibilities), when the engine is cold, the engine coolant temperature sensor must be working properly to signal the PCM to enrich the mixture on cold start. If there is a fault with that sensor, you can experience rough idle idle as you are describing. Other possibilities are a vacuum leak, an air induction fault like a stuck idle air control valve, problems with the mass air flow sensor, defective spark plugs and possibly a weak coil(s). If you desire that this problem be diagnosed by a certified Mechanic, dispatched by YourMechanic right to your location, please request a rough idle diagnostic and the responding certified mechanic will get this resolved for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.
Have a car question? Get free advice from our top-rated mechanics.
Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing