Skip the auto shop - Our mechanics make house calls

Q: Engine light and rpm increased while driving

asked by on

When driving the engine light comes on. The rpm jumps 200 to 300 more and drops right after the car jerks and it feels like the engine is acelerating. This happens on and off. When stop at a light on drive car acelerates by itself. Black smoke and fuel smells. Already change trotle body sensor and fuel sensor. Have been check by 2 mechanics can find problem. Car shots off while driving one time

My car has 200000 miles.
My car has an automatic transmission.

A: This is a common sign of a dirty or failing...

This is a common sign of a dirty or failing mass air flow sensor. The mass air flow sensor is a unit in the intake system that monitors air intake as it is mixed with fuel prior to being injected into the motor. When this is dirty or faulty, this causes an imbalanced air/fuel load to be supplied to the motor which results in an over fueling or under fueling situation depending on the conditions. This type of inconsistent fuel supply to the motor may cause a hesitation, loss of power, a jerking reaction, potentially a bot of black exhaust smoke and typically a strong smell of fuel when this sensor is malfunctioning. When this is not working properly, you may also notice a strong smell of fuel. I would suggest having a professional from Your Mechanic come to your home to diagnose your mass air flow sensor.

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 running funny

Hello - your symptoms suggest that the throttle position sensor has failed. This would not be unusual for a vehicle with your extended mileage. I would recommend having a Car Hesitates during Acceleration Inspection completed by a mobile, professional mechanic,...

Q: Check Engine Light is on - code P0455

Hello. P0455 is the trouble code for a large leak detected by the evaporative emissions control system. The computer will set off this code if it detects a large leak in the evaporative emissions (EVAP) system. The EVAP emissions system...

Q: Idle issues or MAF sensor? 2001 Nissan Maxima

The idle air control valve monitors the air intake as it is mixed with fuel prior to being injected into the engine. This valve is controlled by the vehicle's computer which will adjust idle speed based upon other measurements such...

Related articles

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...
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...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.