Skip the auto shop - Our mechanics make house calls

Q: My RPMs keep going up and down irregularly

asked by on

I drive a 2005 Corrola with manual transmission. I'll be cruising at maybe 4/5th gear at a comfy 2100 RMPs. But if I suddenly give a little gas, it'll immediately shoot to 4000+. Then as I'm accelerating, the RPMs will fall until it appears to catch up with itself. It doesn't lurch or make any weird noise. Normally, if I were to gas it in the same circumstance, the RPMs would just gradually rise in correlation with my speed. This problem occurs at any gear and any speed.

My car has 160000 miles.
My car has a manual transmission.

A: Engine surging can be caused by several iss...

Engine surging can be caused by several issues. Typically in diagnosing these types of issues, you want to start by having your engine scanned for diagnostic troubleshooting codes. If scanning the computer doesn’t pull any codes, the best way to find the issue is with a process of elimination. You will want to find and inspect the following components. One, the mass air flow sensor, can fail or have a bad connection. If this sensor is dirty, faulty, or has a bad connection, it will send the wrong information to the computer, which will possibly attempt to overcompensate with extra fuel causing the surge.

It is always smart to then check your fuel pressure as well. A clogged fuel system can also causes surges. As you press more on the gas pedal, the computer is trying to pump and not receiving the fuel it needs. It then causes the pump to work harder until it gets what the amount of fuel it thinks it should be getting. Once the computer has realized what is going on, it depletes the amount being pumped to the engine and regulates where it needs to be. These issues are typically caused by a worn fuel pump, clogged fuel injectors, or a clogged fuel filter. If none of these is the culprit, turn your attention to the spark plugs and ignition systems. You will want to test for correct voltage and timing at each cylinder. A faulty distributor or set of wires is typically the cause of these symptoms.

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: Electronic door locks not working.

The power door lock actuator is most likely to blame. A trained professional, such as one from YourMechanic, will be able to confirm this and repair your Mazda.

Q: At what RPM should my car be at while idling. My car is a 2000 Mazda 626 automatic.

Hey there. The specifications for the idle speed in gear for a 2.0 liter engine is 500 to 800 rpm. If you have a 2.5 liter engine the specifications are 550 to 750 rpm. Both of these rpm specifications are...

Q: Car overheating and the fan not working.

Hello. Cooling fan failure has been linked to the temperature switch going bad. I would recommend having a technician come out and test the switch and back-probe the fan to verify that it works. I would also recommend having a...

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 to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
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.