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.

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?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. My RPMs keep going up and down irregularly

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: What can cause engine not to crank

Hi, thanks for writing in. This can happen for many reasons such as over torquing the plugs when tightening them, or previously stripped threads in the cylinder. In either case, the result is the plug will result in being blown...

Q: The car shut off at the traffic light, difficulty accelerating

Hello there, ESP will generally not cause the vehicle to die. It sounds like you have a few issues with the lack of power, starting, and the car dying. A few items can cause all three of these. Most common...

Q: My car shows trouble codes P0133 and P0420

Hi there: It appears as if you've got a lot of miscommunication going on with your mechanic. Here are a few basics. First, anytime an error code is triggered, such as the P0133 OBD-II code the issue needs to be...

Related articles

P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...