Skip the auto shop - Our mechanics make house calls

Q: Hunting idle speed and stalling.

asked by on

2003 Honda Civic ES (7th Gen). Used car 2 days before and everything was fine. When I drove it now, it has hunting idle. Saw gas empty on dash although I know it has quarter tank full. Filled up full tank on gas station, and when I tried to start the car, it wont start. Sounds like a bad battery... Pushed start car and it started fine but gas gauge still reads empty though it should be full tank. I cleaned the throttle body and Idle Air Control Valve. Car is fine now. My Question is, what caused my car not to start and read empty fuel although it has full tank? And why it didn't want to start? Car is fine now which reads full tank and runs fine but idle is still 1,300 rpm. Did idle relearn, still wont fix it. I can live with the rpm thing but I don't want to experience the no start thing. Checked battery and Alternator and both are in tip top condition. Everything is fine now but i want to prevent it from happening in the future. Hope you can help. Thanks in advance and God Bless.

My car has 120208 miles.
My car has a manual transmission.

Hi There, It sounds like you may have an issue with your evaporative emissions control system causing the hunting idle problem and the no start issue after filling up your fuel tank. Your car has a small purge valve called a purge solenoid that controls the venting of fumes from the fuel tank as these fumes build up inside, particularly when you are refueling the car with gas. The EVAP system prevents fuel vapors from the fuel tank from escaping into the atmosphere. The EVAP system collects and temporarily stores the fuel vapors in the charcoal canister. The charcoal canister is filled with activated carbon pellets that can absorb the fuel vapors. When the engine is running, the fuel vapors are purged from the canister and burned in the engine. The vent control valve (solenoid) controls the flow of outside air in and out of the charcoal canister. The vent valve is controlled by the engine computer (PCM). Normally the vent valve is open. It closes when the engine computer tests the EVAP system for leaks. If a leak in the EVAP system is detected, the Check Engine light will illuminate on the dash and the trouble code related to the problem will be stored in the engine computer. When an air leak is present in the EVAP system, the MAP sensor will not be able to determine the air density, and the MAF sensor will not be able to determine the volume of air, entering the engine correctly. This will lead to an over fueling situation or an under fueling situation depending on the size of the air leak and engine operating speeds and load. This may eventually lead to catalytic converter problems as well as misfiring problems. I would recommend having an expert from Your Mechanic come to your location to diagnose and inspect your vehicle.

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

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

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: How do I change the auto door lock settings?

Your vehicle can automatically lock the doors when you are driving, for added safety. You can use the multi-information display to customize if you would like the doors to automatically lock when the vehicle is moving at a significant speed,...

Q: my ECM keeps frying and im not sure where the dead short is coming from it fried 2 ecm's already. Help

Most often when there are issues like this, the problem ends up being a poor electrical connection somewhere, or an improper or poor ground. There could also be a problem in the wiring harness that is sending power back somewhere...

Q: My car shows the check engine light, the computer showed code P0455, and it shakes and vibrates at stops and during acceleration.

First, remove and reinstall the gas cap, clear the code P0455, and drive the vehicle for a few days and see if the code comes back. If the code comes back on, then either the gas cap needs replaced...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
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...