Q: Vibration and high idle when i cold start it

asked by on December 10, 2016

When i cold start my truck it has a high idle and vibration when rpm goes down

My car has 104000 miles.
My car has an automatic transmission.

A high idle upon cold start is generally normal for any vehicle as this is part of the cold start enrichment process as the engine warms up. As a general rule, car engines do not like cold weather and do not do operate as well in cold weather. When you start your car in the morning and turn the key to on, the coolant temperature sensor immediately reads the temperature of the coolant and relays this to the computer indicating that the coolant is cold. The computer then knows at this point that it needs to enrich (add more fuel) the air/fuel mixture at startup due to the change in air density. When you start the car, you will notice that it idles high for a period of time until the engine warms up. This is the enrichment cold start process. This is done with what is called a cold start injector which injects more fuel into the motor until the engine reaches a specific operating temperature. The computer simply feeds a little extra gas through the fuel injectors to start the engine and then maintains a certain amount of fuel supply to the motor until it is warm. I would recommend having an expert from YourMechanic come to your location to take a look at your vehicle and diagnose your cold start issue.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

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

What others are asking

Scraping noise

Sometimes its easy to get the hardware in a little crooked when changing brake pads, that or a backing plate might have gotten bent. Take the car back to the guy who did your brakes, they should be happy to...

Power steering pump leaking

If your power steering pump is leaking, that would be the cause of the noise you are hearing. Since a leak exists in the system, the fluid level is likely low. Hydraulic systems depend on an exact amount of fluid...

Turned on heater car started shaking turn it off and on it stopped shaking never did it again. Was snowing why did it do thst?

Hi Tony. Thanks for sending your question to us tonight. When you turn on a heater or AC unit, it causes additional drag on the engine. This can cause small issues like clogged fuel injectors or other components failures to...

When I stop my car it starts to turn off. When I run my car for a bit and turn it off, it won't turn back on when I twist the key.

Hello. If the car doesn't crank then there is likely an issue with the starting or electrical system. If the issue began after you installed the new battery then the first thing I would do is check the battery to...

Driver's side window not working.

A power window has several components, all of which will cause it to stop working. The switch, motor and the regulator. The switch is the button you press to make it go up and down. Since it is on the...

Car loses power when coming to a stop. Radio resets then loses power. Replaced battery and alternator. No code given when this occurs.

Hello and thank you for contacting YourMechanic. Check for any loose ground wires under the dash. There also could be a loose ground wire to the computer causing it to temporary shut down and make everything flicker. Check the ground...

My car isn't starting, it's really cold out. I was wondering how can I start it with this cold weather

Hi there. Given the description of not being able to start your vehicle, when it is cold and jump starting the vehicle without any problem. This leads me to believe the battery does not have enough cold cranking amp capacity....

Truck is running rough, loses power, backfiring noise - 1994 Nissan D21

Hey there. I would check fuel pump output and condition of fuel injectors (flow rate and solenoid resistance). After that, I would evaluate the ignition system, including distributor, plug wires, timing. If you would like to have this checked for...

Headlights not working.

Hello, the first thing to check would be the fuse(s) for the headlamps. If the fuses are good, if it's just the low beam and the hi beams that work ok, I would suspect the multifunction switch. The multifunction switch...

Related articles

The Best Used Cars to Buy If You Live in a Windy Area
If If you live in a windy area, one of the most important things you’re going to be looking for in a used vehicle is the ability to remain stable on the road on even the most blustery days. That...
Can Extreme Cold Temperatures Break Car Windows and Windshields?
Your Your windshield and other windows are extremely important parts of your vehicle’s structural integrity. They provide rigidity in the body and prevent vehicle sway, much like the sway bar does underneath. But once your windows are compromised, they can...
Why Washing Your Car in Winter is Important
Keeping your car clean in winter makes your car last longer. Wash your car in winter to prevent rust under your car and keep ice off your windshield.