I'm a new member to this forum, but have been seeking answers from your experiences for a while. lots of helpful info. I have a question for you...hoping you all can help. I have had my manual 07 Fit sport for the last 125000 miles of its life and love this car. Lately, dealing with rough running and engine coil miss fire codes...however, when replaced, fine for a bit then rough again. Replaced spark plugs and new coils again...same story. Brought to a mechanic for compression check based on valve adjustment comments I've seen...he's testing as I type this. However, mechanic called earlier and told me wiring harness is going bad and he can manipulate the codes by holding certain wires...so I'm inclined to trust him. (And before you say it, no - no mice, garage parked and no chewing evidence). What would my options be at this point...it's getting expensive. I'm being told it's a $1000 + job...(?) Honda new parts? Salvage? On line sources? Any input is appreciated... I'm so bummed she's running rough...want to make her better. Help!

 

Update: valve compression ok

 

Compression test results will only show "bad" when valves are totally burned. The misfires come before that happens. If your valves are toast, chances are that the new coils & plugs would not have temporarily solved the misfires.

Have the valve clearances adjusted. Specify that you want the clearances set to the loose end of specification. Ask for "before and after" measurements and get back to us.

If your problems persist (what brand coilpacks & plugs were installed?) I'd get a Second Opinion before spending $1000... Have not heard of coil circuit wiring problems on Fits.

 

Pay him for diagnostics and have him write down which wires he was moving to created codes. Then look at the connectors near these manipulation points.
7 years it is too short for the wire to give away (unless it is burned) but connectors can corrode.