Skip the auto shop - Our mechanics make house calls

Q: Misfire

asked by on

My rpm gauge bounces around, doesn't rev when it does, it just bounces. Have a slight popping noise when idle or driving. Popps more when fast exceleration. Not so bad on highway. Compression test is good. I have changed plugs, wires, cap, rotor, fuel filter, idle air control valve. Still have problem. What would be more likely, map sensor or injectors?

My car has 233000 miles.
My car has a manual transmission.

A: Hi there. From the description you have giv...

Hi there. From the description you have given, your vehicle has a combination of problems. The erratic tachometer/rpm gauge could be at fault. The tachometer signal from the ignition module could be erratic and may also be the cause of your vehicle’s drivability issue. The popping noise has me concerned. Even though the compression test has passed. There is a possibility, an exhaust valve is not opening properly (ie; a worn camshaft lobe), pushing exhaust gas back into the intake manifold. This popping noise from the engine sounds like a popcorn machine. I recommend your vehicle’s problems be inspected and diagnosed by a certified technician from YourMechanic.

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 won't go over 20 MPH

With the speed limitation and the loud noise, I recommend not driving the vehicle until it has been diagnosed and repaired. It sounds like the vehicle is either in limp mode or a mechanical failure has stopped the vehicle from...

Q: Cylinder 4 Misfire

Hello. Engine misfires can be caused by a wide variety of issues. If you have already replaced the coil and plug for that cylinder then the next thing I would look at is the injector. If the cylinder 4 injector...

Q: is it common for the timing chain to go out on this model truck?

This is not likely related to the timing chain as the truck would not fire at all if the timing chain were out. If the truck does fire occasionally, this suggests you have spark and fuel which is good. This...

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...
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.