Long time lurker, decided to sign up.

My wife has a 2007 Honda Fit base model, auto trans. She has had some trouble with it over the tenure of her ownership and some things the shops have said they just can't figure it out. I have read here there is a problem with the coil packs on these engines, they crack and short out or arc to the engine block from what I have heard/read. She had them replaced at one point and they still have trouble and has a lack of power.

We have noticed when driving at night that the headlights pulse almost as if they are flashing. They also seem very dim. I used the 3M headlight lens restore kit and they seemed a little brighter but after a few weeks they are back to where they were. I can drive around with the high beams on and they look like regular beams. I am on the verge of ordering an HID conversion kit so it has enough light to drive at night.

Lastly today after getting the oil changed I was going to the gas station and noticed that I was getting some backfiring going on while the engine was under load. It sounded like the popping was before the cat. I was at a red light and when it turned green i hit the gas and once it shifted into 2nd is when it felt like power was reduced and the backfiring started. No lights are on on the dash, but when it started popping the check engine light started flashing.

The car has a short ram intake on it from the previous owner, I just ordered a specter air filter for it that should be here tomorrow. My wife would prefer to put the stock intake back on since she isn't into the performance aspect of cars. Since I have taken over the maintenance on it I have switched it to synthetic oil. The car has 143k miles on it. It still gets great gas mileage despite these issues. I have owned all american cars myself so I am new to Honda. I have gotten a lot of help from Explorer Forum for my Mercury Mountaineer so I am hoping I can pull from this community for help on the Fit so I don't have to spend tons of money on diagnostics at a shop.

 

Regards Ignition/Mis-fire Issues:

Three rules:

1 Replace plugs (Denso or NGK Iridium only)
2 Replace coils (Hitachi part # ending 053 only, or OEM)
3 Valve Adjustment. (With your backfiring I would do this FIRST)

++++++++++++

Pulsing lights:

Don't try and address the symptom with new lights. The problem is probably the battery or the connections to it.

The Fit battery is laughably small. If it is more than 5 years old replace it. You should also check the electrolyte level (distilled water) every fall when the temps cool down. Many have replaced the OEM 151R size with a larger 51R size. SEARCH for a topic here, to see what you need for the conversion.

Many USA batteries come with terminals that are too small for the Honda clamps. Try to pivot the battery terminals without loosening them. If they move you need to buy battery terminal shims.

That's enough for now, please report back with your findings.

 

Flickering lights (low beam only) typically covered by recall contact in switch connector.
Not sure if modded intake has anything to do with it.

 

Lights could be a bad alternator also. The fit headlights are pretty crummy but a slight headlight adjustment can help. It is possible to slightly raise the low beams via adjustment screws. It does improve lighting a lot.

 

A while back I had the pulsing lights as well and couldn't for the life figure it out. Turned out the voltage regulator in the alternator (common problem) was bad. Although the alternator was still in good shape, I replaced it and the problem went away.