Q: Short-term fuel trim swinging plus or minus 10% during driving

asked by on

Is it normal for a short-term fuel trim to swing plus or minus 10% during driving? It happens during every acceleration and deceleration. I've got a new car as my last one had a bad engine.

Yes, this is normal when you accelerate and decelerate. Your vehicle will add fuel at times, and when you take your foot off the gas, it will subtract. This is normal for any vehicle, even my Toyota does this. Once you’re at a steady speed, the trim will usually be around plus or minus 1% to 2%, at 36,000 miles.

It’s the opposite when accelerating and decelerating in short periods, the short-term fuel trim will go up and down more noticeably. That’s why it’s called short-term fuel trim. The more important data to observe is analyzing the long-term fuel trim over time. That gives you a better idea of the overall health of your engine and your fuel injection system.

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. Short-term fuel trim swinging plus or minus 10% during driving

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: Is it OK to drive with one cylinder at 70 psi?

Unfortunately, there is no definite way to tell how much longer your engine will last. Generally, a cylinder needs at least a minimum of 100 psi in order to run. In your case, this is not happening, which means the...

Q: Brakes screech, car jerks and rattles during deceleration

The noise from your brakes is most likely going to be the pad material getting wet and causing the noise. Changing to a high quality pad can fix this. The jerking on deceleration is in the transmission and may need...

Q: Automatic transmission programming problem

While I agree that this is all probably built into the programming of the transmission computer, after looking at the Mazda service information, I see no TSB's that states Mazda has any updates available in transmission programming to address any...

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...
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...
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...