Skip the auto shop - Our mechanics make house calls

Q: Why does my car idle out of control?

asked by on

My Integra has been idling recently from 850 rpm to close to 2000 rpm back and forth once the car slows down. If I disconnect and reconnect the sensor (tps) it starts to regulate the rpm but after a while it goes back to idling up and down. What is wrong with the car?

My car has 190000 miles.
My car has a manual transmission.

A: Hi, thanks for writing in. This is a common...

Hi, thanks for writing in. This is a common sign of a failing idle air control valve. This is a unit that regulates the air flow into the engine as it is mixed with fuel prior to being injected into the motor. When this is not working properly, it may pick up incorrect readings causing the fuel system to supply too much or too little fuel resulting in the erratic idling you describe. This may also be caused by a vacuum leak which can case an irregular idle depending on where the leak may be coming from. Excess air coming into the intake system (vacuum leak) will cause the engine to surge also as you describe. I would recommend having an expert from Your Mechanic come to your home to diagnose this condition to determine the cause of this.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 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

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: Vehicle idling rough once warm

This might be due to a vacuum leak. Vacuum leaks are common in older vehicles because of the age of rubber lines, gaskets, etc. The vacuum leaks alter the air fuel mixture and as the engine tries to adjust it,...

Q: Where does ignition usually draw its power? 89 wrangler with 94 chevy 350 and wiring. I'm not getting power to the key. 1989 Jeep Wrangler

Hello - usually power to the ignition switch, engine swap or not, comes through the fuse block. So, first thing to check is the appropriate fuse for the ignition from the Jeep Owners Manual. With the engine swap, unless you...

Q: i have a 2010 acura tsx 2.4L, what would you quote me for these recommended services?

Hi there. In order to provide any quote for the services you listed, we'll need to fill out a quote request for each service; as we need much more information from you than was provided. You can access the service...

Related articles

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...
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...
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.