Hey Everyone, I recently bought a 2007 Honda Fit about a week and a half ago. It has roughly 67,000 miles on it. Currently, I have a love hate relationship with the car. Literally the day after buying the car I was experiencing the rough idles at read lights on my way home (bumper to bumper commute on way home, straight shoot to work in the morning). No issues in the morning usually and the car runs great! There was some rough times accelerating/ decelerating the car. RPMs would take a massive drop during deceleration. I guess this has to relate with misfires.

I swapped the spark plugs out two days ago, which gave a noticeable improvement with the car with the acceleration and deceleration issues. However, still experiencing some misfires from time to time. Also, now the RPM drops between 700-500 while at idle without the AC on. With AC on easily between 800-1000 rpm with performance improvements as well. My next step is to swap out all ignition coils. Should this do the trick, or is there something else I should be aware of? I know there is the big three with fits (spark plugs, coils, and valve adjustment). Has anyone else experienced similar problems like this before, and if so, how did you fix them?

I just bought this car after my old one gave out on me, dont really have money for a new car. Please help!

Have a great weekend-EL

 

Yes, swap the ignition coils! At 67k it shouldn't be due for a valve adjustment, but definitely put it on your list of things to do down the road. Keep us updated!

 

My car does it too since 2014; massive drop at deceleration is due to the fuel cut, however old motor mounts and engine system wear make it more noticeable I could speculate that throttle body control wear is responsible for that

Also, now the RPM drops between 700-500 while at idle without the AC on. NORMAL
With AC on easily between 800-1000 rpm with performance improvements as well. NORMAL

 

@doctor J - So do you think the ignition coils could be the culprit, or should I get the throttle body cleaned as well? How safe do you consider your vehicle to be?

 

I would recommend inspection of the valve clearances at 61,000 miles the valve clearances were 8 mils for both intakes and exhaust valves (should be 6 to 7 mils for intake, 10 to 11 for exhaust)

 

Bad ignition coils on my car showed up as a heavy jolt when idling in drive. (California car) my relative who brought car from New Jersey still has original "red tip" coils, but she drives very little.
I performed "throttle body bore wipe" and idle relearn which did not get rid of the issue completely. I don't think the rough fuel cut poses significant safety issue, driving next to a rival gang member in big powerful car or impaired driver is far more dangerous

 

Defintely wouldn’t be bad idea to replace the coils , but could it be a fuel thing perhaps? I’m no engine guru, but that’s not many miles for its age so I feel like it could sat around and gunked up the fuel system/injectors you could try and dump some “injector cleaner fuel additive” stuff in the tank - or if you can swing it - maybe have them removed from the car and cleaned?

i had a Volvo that ran weak and rough and I sent my injectors out to be cleaned (cost me $75ish and I couldn’t drive for 2-3days until I got them back from the injection shop) but it ran much better afterwards.

good luck gettin things figured out!

 

These cars are also sensitive to type of spark plug used. Did you replace with the OEM type iridium plugs?

Is it an automatic or manual? Asking because I'm wondering if the massive drop on deceleration is due to the automatic downshifting.

 

The fuel injected engines use fuel cut (injectors off) during deceleration, the injection resumes when rpm fall close to idle (based on engine load and temperature)

 

Same with all modern fuel injected cars. Still shouldn't cause a drastic deceleration. I don't find the little 1.5 to provide much engine breaking at all. Our little Fit increases speed going downhill in 5th gear while off throttle. Granted, we live in the mountains.

I'm wondering it the transmission is downshifting. It would take a third gear, 5,000 rpm downshiift to slow down our Fit going downhill.

 

With throttle completely closed and vehicle is coasting on the flat road from speeds above 45mph the AT will downshift from 5th to 4th at 31 mph (I'm feeling it) and from 4th to 1st at 10 mph
The downshift shows up as bumped rpms. Hopefully the fuel resume and 4 to 1 shift are not happening at the same time otherwise the jolt will be excessive! (not to mention TC unlock!)
So out of tune engine (for whatever reason) will result in very unpleasant experience, similar to me driving stick shift (in my 1979 Supra)

 

Just a thought,did you change all 8 spark plugs?
Ben

 

This option is not available for US market Fit (no CVT and idle speed control valve either)!

 

Ah that explains it then. I have the cvt with 8 plugs, over here (UK) a lot of independent garages are not aware that the vehicle has 8 spark plugs. Not that my car ever goes to a garage, I have had it for 15 years great little reliable car.
Ben