Q: Engine misfires and ticking sound on startup, coasting, and acceleration.

asked by on October 25, 2016

When I first start my car the engine makes a loudish and consistent knocking sound coming from the upper half of the engine on the drivers side. None of the vales seem loose and I've checked for leaks and can't find any. After around 5 minutes of running the rpms lower and the knocking stops. When I accelerate hard ito starts knocking again, but only during the time I'm using the gas pedal. With the misfires it's fine on idle and startup but is only an issue on accelerating and coasting. Such as when I'm on the freeway and let off the gas a little, or starting from a stop at a red light. The service engine/check engine light has not come on at anytime the misfires occur. The light does work though as I've put the key in the 2nd position, without starting the car, and the light works during the testing phase. The misfires are always an issue on acceleration whether or not the car has been running for a while. I've replaced the spark plugs, cleaned the throttle body, and used fuelcleaner

My car has 152687 miles.
My car has an automatic transmission.

Mass Airflow Sensor Replacement $188.36 - $786.53 Get a Quote
Engine is misfiring Inspection $94.99 - $114.99 Get a Quote

The noise in the engine may be from running with the ignition timing too far advanced from a malfunctioning mass air flow sensor. The mass air flow sensor could be giving false readings, which will cause the computer to compensate by injecting less fuel into the engine. This will cause the engine to knock and run with less power and may misfire due to the issue. Have the vehicle computer scanned and take a data reading of the mass air sensor to see if it is reading the metrics. If it is incorrect then you may not get codes but will need to have the mass airflow sensor replaced. If you need assistance in diagnosing this issue, a certified YourMechanic technician can come to your location to inspect your engine misfire.

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


Experienced Mechanic?

Earn up to $70/hr

What others are asking

Check Engine and VSC warning lights
Hello. This comes up quite often on this vehicle. It is caused by a bad rotational rate sensor. This sensor is used for the VSC and other systems to determine how the vehicle is swaying from side to side or...
Squeaking noise on a 2001 Honda CR-V
Not necessarily. There are so many things that can cause noises. When you take your foot off the gas, the first thing I'd say would be to go and look under the hood and see if any motor mounts (https://www.yourmechanic.com/services/engine-mount-replacement)...
MY CAR IS OVERHEATING AND THE ENGINE LIGHT IS ON
The code P2076 is for the intake manifold runner control, and the other code P0067 does not show that it goes to the car and is not listed as a possible code. Your overheating should be checked before driving any...
My transmission slips out of fear at high speed but not all the time.
This is a symptom of worn or damaged gears within the transmission. It can also be a mis-adjusted shifter linkage, not allowing the gear to fully engage. If your clutch is going bad, you will notice the engine accelerate faster...
Changed throttle body assembly, now it won't start
Hi and thanks for contacting YourMechanic. The problem might be with the crankshaft position sensor (https://www.yourmechanic.com/services/crankshaft-position-sensor-replacement) being effected by heat. This can be verified by measuring the resistance of the crankshaft sensor with a digital volt ohm meter (DVOM) and...
I need to replace the crankshaft sensor. Where is it located in the motor?
Hello. Carbon buildup and other issues can cause these sensors to fail prematurely. You will need to raise the vehicle to access the sensor best. Once below the right, or passenger, side of the vehicle, you will want to look...
Engine does not turn over
Hello. The symptoms you describe are commonly caused by issues with the battery or starting system. If the battery runs low it will not have enough power to crank the engine, which may result in an engine that does not...
Reduced Engine Power
Hello, thank you for writing in. With the car seeming to have issues with the extreme cold weather, there may not be anything technically wrong with it. It is not uncommon for vehicles to struggle with this. You may want...
T-belt light for 2016 hiace manual transmission
Hi there. Turn ignition switch off. Press and hold the odometer display button while turning ignition on. Hold button down for 5 seconds then release button. This will reset the reminder light for the timing belt change. If you need...

Related articles

Can a Bad Sensor Prevent a Car From Starting?
If your car isn't starting or has a hard time starting, a faulty sensor may be to blame. Car sensors monitor data to keep your car running smoothly.
Symptoms of a Bad or Failing Coolant Level Sensor
If the Coolant Light stays on permanently, there is low coolant, or the engine is overheating, you may have to replace the coolant level sensor.
Symptoms of a Bad or Failing Transmission Speed Sensor
Common signs include harsh or improper shifting, cruise control not working, and the Check Engine Light coming on.