Skip the auto shop - Our mechanics make house calls

Q: My car's fuel efficiency is poor and it starts rough

asked by on

I got my car read at autozone and they told me it's either the gas cap that went bad which I replaced still doing the same thing, purged solenoid canister, but I think it's the MAF also I noticed that my dipstick tube is non existing it's just the stick and oil is leaking but has no signs in the driveway

My car has 146000 miles.
My car has a manual transmission.

There is a valve that is by the fuel neck next to the fuel filler inlet that measures the fumes from the gas cap and related areas. This valve is known as the EVAP purge solenoid valve. This valve controls the pressure in the fuel system.

If the valve fails, it will leak and the fuel vapor sensor will pick this up. When the valve fails, the computer will increase the amount of fuel to max and cause the engine to run rich and have a rough idle.

Check the valve with a fumes sniffer and see if there are any vapors present. If so, then the valve needs to be replaced. If there are no fumes present, then the valve still could have failed electronically.

If you need further assistance with your vehicle, then seek out a professional, such as one from YourMechanic, to help properly diagnose your car’s rough idle and help you fix it accordingly.

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: Car idling rough

The problem could be one of the intake ducts / boots. These transfer the air from the atmosphere, though the filter, into the turbocharger, through the intercooler, and into the throttle body. If air gets lost due to a bad...

Q: How do I view the average fuel economy in the multi-information display?

The average fuel economy shows you the mpg that your vehicle has been averaging while you drive. The average fuel economy is tied to the trip meters, and will be reset when the trip meters are reset. You can access...

Q: The speedometer, odometer, & mileage gauges are not working.

This is likely related to what is called a speed input/output shaft sensor which is a sensor mounted down on the transmission that monitors the speed of the output shaft of the transmission. This is relayed to your ECU which...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
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...