As the title says, I'm experiencing a stutter under light acceleration in my 2009 Fit Sport. It has a 153k and never had any issues before. What's interesting is that under normal and hard acceleration, the car does fine. We went on a 16 hour road trip this weekend, which was mostly highway, and it has no issues at highway speeds, or when accelerating down the on ramp. It seems like it stutters under light acceleration. It almost feels like the transmission is confused on what gear to be in and is shifting up too early, causing a low rpm stutter. However, I'm not entirely sure if it's a engine or transmission problem, but I find it odd that under wide open throttle and moderate acceleration, it runs like a champ. No check engine light has come on at this time. What are your thoughts?

 

What rpm are you applying light acceleration at? Might be the plugs or coils.

I have a 09 Fit Sport 5-speed (163k miles), and I notice if I'm trying to lightly accelerate around 2k rpm in a higher gear under load, the engine bogs and hesitates.

Downshift and then it isn't an issue.

 

If you've had any recent maintenance done, start by inspecting the labor associated with it. That done, you can move on to general inspection of associated areas.

No CEL means it's PMCS time. While I love the low cost of maintaining a small high-efficiency engine, I find it can be a little frustrating that almost any excess resistance/impaired function can cause poor acceleration. The first thing to check is always spark plugs as mentioned above. Their looseness is a common fault that could definitely create your symptom.

Then, follow your gut and check the transmission fluid level.
If the issue still isn't resolved, proceed to inspect steering and front-end brake components for wear. Misalignment and/or warped rotors can both bog down the engine under acceleration by creating rolling resistance.

 

It's an auto trans. It does seem to do it around 2k. It will stutter for a sec or 2, then down shift and be fine. But, it didn't used to do this. This is what makes me think it may be engine/trans issues. No CEL tho...so I'm guessing at this point.

 

The last service was about 5 months ago for an oil change, so I don't think that's the issue.

It's definitely not the brakes, tires, wheels, or anything drivetrain related, as far as rolling resistance. It's not a constant sluggishness, it's a stutter. I'll check the trans fluid, but if it were a fluid issue, wouldn't I expect issues in all rpm ranges and all driving conditions?

 

I'm not versed in transmission repairs and have never disassembled one to obtain the experience needed to speculate. My only experiences with transmission faults have been pertaining to shifting misbehaviors which have thus-far been resolved by changing transmission fluid and ensuring proper fill level. The faults I've resolved so far on that front have been:

1. Clutch slip in automatic trans (claimed excess detergents in replacement Toyota "World Standard ATF")
2. gear "hunting" in automatic (low fluid level)
3. Simulated clutch slip (severe, low fluid level CVT)

In regards to the car lacking other performance faults, i've noticed that folks, myself included, tend not to notice when faults develop gradually vs. suddenly. It is possible that your symptom is the result of a sudden failure, I just listed the faults that I think are the most likely culprits.

If we're thinking that it's specifically second gear that's producing the fault, I couldn't find any information for you in my attempt at a general search. I understand that in an automatic transmission gears are selected by means of fluid pressurization, but beyond that I'm stumped. I'll start doing more reading about automatic transmission operations.

Now in regards to engine performance faults that I mentioned, I'd suspect they be most noticable entering first gear because it's the most notable transition in shifting being that yuh go from stopped to moving, but in an automatic you just throw it in drive and well.. it's ******* complicated. Here's a LINK to an incredibly condensed 20 min video disassembling and explaining a modern automatic Honda transmission.

Watching it helped me realize that the reason I'm recommending that you may be overlooking engine performance faults is not only that I haven't heard complaints pertaining to the trans but that such a fault would be well beyond my present ability to comprehend, and much more to diagnose.

 

Thanks for the indepth reply. I'll check the fluid after the hurricane passes. But, I still am not convinced it's not an engine problem. But what's stumping me is that under heavy load, it runs like a dream! I would think if the coils were going out, or a fouled spark plug, then it would be worse under load.

 

Happy to be of service if I have! Just here to learn from the puzzles, sincerely.
Your confidence in the fault not being engine-side is actually encouraging. I'm a big fan of following gut feelings pertaining to what isn't wrong, so long as those gut feelings ain't founded on unwillingness to repeat or scrutinize past work


Despite further head-scratching I'm no closer to a sense of comfort with automatics. All the veins in them look like a circuit board, and my best conclusion is that the length of a vein could be used to regulate fluid flow to a specific area to take place after flow to a port earlier in the same or a nearby vein originating in the same or similar location..
Like if you're sucking water up a straw with several holes in the side, each an inch apart vertically. Vacuum would need to be stronger to overcome loss of fluid through lower holes and get all the way to yer mouth.

Hopefully someone chimes in with a better understanding 😂

Oh uh, in that video I linked to earlier, the gentleman in it referred to shift solenoids getting dirty and causing issues. Stated that they were accessible externally and that one could remove, wipe clean, and reinstall, though I believe that it's common for a single solenoid to be responsible for multiple gears (2nd and 3rd for example).

If the fluid level is just dandy, checking out the related solenoid may be a beneficial shot in dim light. I'll check the service manual for component location. Hope you're fairing the hurricane well!!

 

I thought the same with my Alfa 4C -- car performed awesome under wide open throttle, but it had a lumpy idle and bizarre mild acceleration manners. Turns out the previous owner had installed Brisk Silver Racing plugs (rated for 12k miles) and it was well past that mileage. Replaced them with some longer lasting iridium ones and those engine issues were gone!

KSijK0m.mp4

 

I spent a little time digging through the transmission troubleshooting section of the manual. I'll upload the list so yuh can see for yourself. There's no listed fault addressing your symptom that would also be limited to the second gear shift specifically and not include a CEL unless we're going with the phrasing "Excessive shock or engine revs up abnormally high on 1-2 upshift or 2-1 downshift."

 

I'm assuming you didn't get a CEL? I hate to throw parts at something without a positive diagnosis.

 

Alright, we took another road trip this past weekend. I was about to pin point the symptoms a bit better. Anywhere from 20 mph and above, regardless of gear, the car kind of stutters/stalls around 2k rpm. It feels like a misfire, but I'm not getting a CEL or any codes at all. Under heavy load and wide open throttle, there is no issues. The issue is exacerbated under light to moderate acceleration. I'm looking at spark plugs and coils on Rock Auto. I can replace all for around $150. I hate throwing parts at a car, but it really has the feel of coil issues and misfire. I'm just not completely convinced though. I had an older Mustang years back, and when the coil started to go out, it had the same feeling and symptoms. However, it got worse under load. This car is opposite. It does outstanding under load!

 

Don't necessarily need to replace the spark plugs, could just check em for torque/add some thread-locker n re-torque. definitely shouldn't need coils without a code, but i'm not one of the unlucky guys that had a coil go out. its certainly true that a system wears progressively before failing. Had no codes on my 09 tacoma, but my innova code reader showed that the emissions system wasn't operating efficiently, indicated by orange color coding. have been troubleshooting idle vibration and general crappy performance for some months (mostly head-scratching). New o2s and cats cleaned it up a great deal.

i'd recommend basic stuff for yuh. check plugs and throw in a valve adjustment if you can. can pull procedures for yuh from the service manual.

 

thanks for the input. I sure feels like a coil causing a misfire, but again...no codes! And just for others reading this, I've done the normal stuff. Oil level is good, transmission fluid level is good, and clean. The previous owner kept it well maintained. We just rolled 150k on this past road trip. Not sure if the plugs and coils have ever been replaced.

 

Welp, my wife called and said on the way to work the check engine light and the traction control light came on. Not sure what the relationship with the traction control light is, but I'm assuming the ECM finally recognized the misfire. I'll run the codes once she gets home and see what it spits out, but I'd be willing to bet that it will be a misfire code...

I've got some laser iridium spark plugs and ignition coils in my Rock Auto shopping cart. If it spits out a misfire code, I'll go ahead and replace all 4 while I'm at it.

I'll keep yal posted...!!!

 

 

New iridium spark plugs and ignition coils fixed the problem.

 

Thanks for the update and glad to hear it’s fixed. Hate whenever someone posts a problem and doesn’t close the loop so to speak.
Just curious any loose plugs?

 

You're welcome. I feel the same way. I like closure! Otherwise the thread doesn't provide much usefulness for others down the road.

The only thing I could tell was the third from the left plug was sorta loose. It didn't take much to break it loose, and the coil looked brownish, like water got down in there and caused rust. But, interestingly, the code reader said cylinder 1 misfire. Is the first cylinder starting on the left??

 

First cylinder is belt-side. Glad to hear the issue is fixed!
Spark plugs can actually have their own sort of blow-by. Gasses from combustion escaping through the threads around the plug if it loosens or through the body of the plug, like between the porcelain and metal bits. Much cheaper to address than blow-by going around the piston rings, but a touch frustrating! Can wind up with faulty plugs easily. Every time I change mine I notice at least one discolored, some loosening, or all, shockingly. Despite the discoloration I've yet to encounter any failed coils, though i havent like, ohmed them or anything.
I change my plugs ~ every 15-20,000 miles due to use of IK22s, but have a feeling id be checking them just as often even if I didn't have to change them.​​​​​​