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: Power steering intermittently goes out

Hello, thank you for writing in. You need to start by considering the symptoms. If they are exactly the same, the issue may have been a faulty replacement part. It is not terribly uncommon, but is even more frequent in...

Q: Help with Kia Sport shift / TPS

The TPS controls the fuel supply in all modes. Changing the mode will not bypass the TPS as this is the car's method of regulating the amount of fuel being injected into the motor based upon the position of your...

Q: Check engine light on

The Check Engine Light (CEL) could have illuminated for many reasons of course inasmuch as there are thousands of Diagnostic Trouble codes that could set the CEL. You can borrow a Code Scanner from Autozone and manually force the reset....

Related articles

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.
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.