My parents' 2007 Honda Fit 5spd 1.5L has had a stutter/shudder, usually during acceleration. It has slowly been getting worse, and yesterday as I was accelerating off a ramp, it was stuttering and the engine light started blinking. I checked the OBD2 codes when I got home and it showed multiple cylinder misfires. I'm guessing it's fuel related, maybe fuel filter won't let enough fuel through fast enough??? I looked up fuel filters for this vehicle and it seems that there is only a fuel screen on the pump, but nothing inline, which seems strange. Need someone to point me in the right direction.

 

I would for sure check the spark plugs as the first thing. All torqued to 20 lbs-ft.

Spark plugs ejecting is a fairly common problem on these engines, and the first symptom is a code for misfire...

 

Ah, good idea. Thanks I'll check them soon!

 

Only the #4 spark plug wasn't tight, but they are all definitely worn. It's showing P0300, P0301,P0303, and P0304 misfire codes, and a P0420 "catalyst system efficiency below threshold bank1". When i read them a few months ago, it only had the P0420. It doesn't seem like that many cylinders would be misfiring unless it it something in the ecm or something fuel-related. Maybe? ¯\_(ツ)_/¯ I'll replace the plugs and maybe the fuel pump assembly and see what happens.
Also, what about the coil packs? How often do they need replacing? The far right one in the pic is #4

 

The fourth one doesn't look good compared to the others.

If you decide to replace them (or at least one of them), don't cheap out and buy OE (or OE brand, which is Hitachi).

 

You mean NGK for the spark plugs and Hitachi for the coils.

 

Meant Hitachi for the coils!

Don't think Hitachi makes spark plugs.

 

I understood, thanks!

 

I'm brand new to this forum and happened to see your issue.
If you haven't completed it yet, might I suggest to check for that grey/white corrosion at either end of the coils.
I had a similar issue and when I came to change the plugs I saw this. I cleaned these and put on a touch of electrical grease to minimize the potential of it returning. I haven't had the problem since.
It seems that the ECU is very sensitive to this sort of thing and responds in that way.

 

If the coils have never been replaced consider replacing both plugs and coils.

 

Coils and plugs ordered. Thanks for all the input! I'll update when installed.

 

I like the sound of that. Good job.

 

Got the coils and plugs installed last night, and took it for a test drive. Runs like a dream! No stuttering or hesitation. Thanks to all for pointing me in the right direction!

 

@Mr. Independent Wheels I love it when a plan comes together.