Honda Fit Sport 2008, 167k miles, owned by me six months. I bought it in California and drove it cross-country to North Carolina. Around 2/3 of the way here, I noticed some stuttering at middle-low RPM (2000-2500). It has gotten worse, but is not yet terribly bad. It is as off the key were turned off for a fraction of a second. Anyone old enough to remember vapour lock? It’s like that. At high RPM (3000 and up), runs fine, If I feather the pedal (low RPM), it’s fine. Air filter doesn’t look dirty, but could that possibly cause “mid-RPM stutter”? If it were a fuel pump or fuel filter, I would expect high RPM to be almost impossible.
Sounds like it could be spark plugs (amongst many other possibilities). When were the plugs last changed?
Not sure. I’m a “new” owner, and only about 5,000 for my ownership. I may try that. Do you think bad plugs would only cut out at certain range of RPMs? It idles fine, revs up fine. It only cuts out around 2,000-2,500 RPM. If I drive like Grandpa, no problem. If I drive like Schumacher, no problem.
Is there a “check engine light” on currently or have you seen one come on since the problem began?
+1 here for spark plugs. Try replacing them as a (cheap) first step. Can’t hurt.
No check engine light. I guess if n one ever heard of this range of RPM issue, I can just start replacing things not really having any clue what would cause it.
@Lance666 Well, if you don’t want to replace spark plugs, you can just let it get bad enough to throw a CEL. These things rarely get better with time!
This sounds like an ignition problem. Mid-rpm spark miss. Not enough turbulence in the combustion chamber at lower RPM to fully ignite with a weak spark, hence, the random miss. Spark plugs are cheap and easy, as are plug wires. With the info you’ve typed into the internet, this is as close as I (and likely others) can get.
Also re: plugs, use only the ones specified in the owners manual or underhood sticker. Anything else is an experiment. You might have an experimental set of plugs in there right now.
I agree with @shanonia. My dad gave my son his old 2003 Camry. It was running ok but stuttering a little and fuel economy was down. I bought a set of Denso Iridium plugs, which are considered OEM, and popped em in. The plugs I pulled were not OEM and were gapped wrong. As soon as the Denso’s went in the idle smoothed out, the power picked up, and the fuel economy improved dramatically. Ignition parts, including plugs, should always be OEM or you often end up with weird issues that don’t go away until you go back to OEM. Especially Japanese cars.
Your Honda FIT has a drive-by-wire electronic throttle body.
This means that instead of having a throttle cable between the accelerator pedal and the throttle body, the throttle body is electronically controlled via the vehicle computer.
When these electronic throttle bodies become dirty, it can cause all sorts of driveability problems.
If there’s no Check Engine light on, I don’t see a reason to be replacing secondary ignition components because there’s no misfire indicated.
Here’s how to clean the electronic throttle body on your vehicle.
Tester
Try new plugs, but my guess is the EGR valve is carboned up.
Sometimes a report of “stuttering” at mid-speeds is due to torque-converter lock-up shudder. If you have an automatic transmission & it sort of feels like running over a cattle guard when it stutters, consider that a possible explanation too. Here’s a quick test you can do: If it is happening and you press lightly on the brakes, does it go away? If so, that’s consistent with TC shudder.