Hi everyone,
I've got a JDM 2002 Honda Fit in New Zealand. I recently replaced all 8 coil packs a few months back to fix a previous engine misfire (but didn't replace spark plugs). Now, it seems I'm having issues while accelerating. The engine seems to be down on power until about 50km/h or so and then you can feel the car take off (at least relative to what that little engine can do...). Along the way you can feel periods of a slight shudder, or grinding? or rough running when accelerating from a stop, then again from around 20-30km/h, then again around 40-45km/h or something along those lines. The roughness kind of comes and goes as you accelerate, though it is always lacking power until it seems to "break free" somewhere between 50 and 60km/h.

Shortly after the coil packs were replaced, I noticed this slight shudder for a second or two when accelerating from a stop, but it was very slight and only from when stopped. Now it seems to have gotten significantly worse all of a sudden (as described above).

Probably unrelated, I had to jumpstart the car a couple weeks ago. It had been running fine after that until now. I have already done the ECU/PCM reset procedure and it didn't seem to make a difference.

Also, problem may seem to be worse after the engine has warmed up?? though not positive on that one.

I've got a couple theories, but am keen to hear what everyone here thinks. Thanks in advance for your help!

 

8 coil packs?

My guess from your description is that it's fuel related. Leaky or sticking injector maybe?

A good place to start is to pull the plugs, inspect for fouling, and replace with new ones. That will tell you if it's running rich and, by replacing the plugs, eliminate a possibility for very little time and money.

 

yup, the 1.3l engine apparently uses 2 spark plugs/cylinder.

a bit of an update...
all 8 spark plugs have now been replaced. Didn't really make a difference.

The ECU/PCM reset is more precautionary than anything. From what I've been reading, it isn't necessary most of the time. I just did it in case the shuddering I was feeling was CVT related.

I've tried to clean out the EGR valve as best I could, and that doesn't seem to have made a difference.

The car runs perfectly when it is cold, but shortly after the cold engine light goes out, the engine starts misbehaving... sputtering, etc. under load when I try to accelerate.

Any other thoughts? I'm banging my head on this one

 

How did the plugs look? My guess is still fuel related issue.

 

so, I haven't done any work to the car since the last post, but a couple drives later, and (knock on wood), it seems a bit better, though not completely. Previous test drives were quick down the the road and back sort of thing. Maybe it just took a little longer for some things to take effect???
I do notice some audible knocking while trying to accelerate moderately hard around 60-80km though... It is somewhat random (not rhythmic with the engine), though fairly loud as I can hear it clearly with the windows up and radio off.

probably unrelated, but the day before the problems showed up, the car was fueled up at a gas station different from normal, though still from the same brand/chain as normal (Caltex). There was maybe about 1/4 tank left before filling it up. Could I have gotten some unlucky dodgy gas from this station?

Also tried to check for fault codes through the OBD, but it came back empty. No fault codes.

 

another update...
I reduced the spark plug gap to about 0.032" - 0.035" as recommended in some other posts, and that seems to have smoothed out the ride (for now...)

I imagine this 'fix' will only be temporary. What should I be looking at to fix it more long term? New coil packs? adjust the valves??

 

Hmm...that makes me wonder if you're not getting a good enough spark from your coils. Generally speaking you can open up the gap with hotter spark. You may have discovered something with shrinking the gap.

What coils are on the car? Hitachi or Denso are known to hold up great. Chinese no name stuff is poor right out of the box and gets worse with age.

Too bad you have 8 of the darn things!

 

yeah, I was suspecting coils as well. Unfortunately they are "aliexpress specials". As originals are 8x the price here in NZ and the car is 15+ years old, I thought I could maybe at least get a year out of the chinese coils.

do you reckon this spark plug experiment eliminates possible causes such as faulty O2 sensors, engine/exhaust air leaks, fuel injectors, etc?

 

O2 sensors and the catilitic converter is clogged up.
It's a pricey repair but it'll fix the stutter.
I just experienced the same description on a friend's 2007 GD3 with 287K miles on the engine. Afterwards ran without hesitation
GLWR.
BIG MIKE : ^ )

Check the cat with inferred gun/ thermometer. Coming in temp vs exit temp. The ext temp should be much hotter.

 

wouldn't the o2 sensor throw up a fault code though??
my OBDII reader isn't picking up any

 

One more confusing anecdote. It may just be in my head, but it seems the car runs more smoothly in the mornings and evenings than in the middle of the day. Also, yesterday I took the car out for about a 20 minute drive a little before sunset. It wasn't performing so smoothly. It was parked for about 20-30 minutes. In that time, there was a short and sudden heavy rainfall. The storm passed and we drove back for another 20 minute drive. By this time the sun had set and it was 'dusk'. On the drive back though, the car behaved noticeably better. Could the humidity in the air have anything to do with it? Or did the rain somehow get anywhere? Colder air temperatures? I'm in a fairly humid environment (humidity levels increase significanly when the sun is down) and at the moment temperatures during a day will range from 9C to 16C.
It all seems far fetched to me though....

 

I’m using the Torque Lite app on my phone with the OBDII. There’s some graphs it says I can pick up like “O2 Sensor1 Equivalence Ratio”, “O2 Volts Bank 1 sensor 1” (and 4 sensors with bank1 and 4 sensors with bank 2), and “mass air flow rate”. It also has something called a “Fuel / Air status widget”. Is there something I can look out for with these outputs that may be an indicator of O2 sensors or Mass Flow sensors operating incorrectly but not bad enough to throw a fault code? Thanks again!