UPDATE 2: This year (For the first time) I installed snow tires on 15 inch wheels vs the normal 16 wheels (So taller sidewall). The ride is now less jittery and the rattle has gone away almost completely. The different vibration frequency of the tires has made the rattle only happen over pretty rough pavement and has more clearly separated the rattle from any engine excitement. So now I am 100% sure I am dealing with a heat shield type rattle.

UPDATE: Since the sound has returned due to colder weather I am starting to zero in on the source.

Fundamental observation: The engine runs too good to be making random noises intermittently that go away and come back months apart. I’ve driven this car 99% of the time with the radio off so know the sound of this engine .

Secondary observation: The engine vibrations pass through frequencies that excite things around the engine. From time to time I can get my keychain in the ignition to rattle with engine rpm.

Secondary Observation: The sound can be triggered after driving on bumping roads. It starts with a very slight rattle and then can be excited by the vibration of the engine. It also can be triggered in a right turn. I also believe the vibration can be started (then further excited by engine vibration) by airflow across the front of the car (like driving up an incline going over bridge).

Secondary Observation: Occurs more frequently during cold weather which could be due to change in part fitment.

What I am zoning in on: I think the noise is an initial rattle from a heat shield (or other thin metal part) that starts to rattle due to bumps/airflow and then gets excited by a range of engine rpm. It is so intermittent because you need both the initial vibration and then the rpm range.

Next step is a visit to a Honda master mechanic to look around for potential metal things that can vibrate.

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Original description below:


Any ideas on this one?

2013 Fit sport 5pd Manual
100,500 Miles. New Spark Plugs, Valve Adjustment recently done (same time as plugs). Car was beginning to make this noise before the Plugs and Valve adjustment. I have owned since 000005 miles and this is a new sound. The car has been carefully maintained since new. Original A/C compressor, alternator, coolant pump, coil packs, and injectors.

When accelerating under load (Hill, faster acceleration) the engine makes alot of popping or electrical “cracking” noises for a few seconds. Typically 3,000 to 4,000 rpm. While this noise is happening I can change the intensity by increasing/decreasing throttle. The noise is intermittent and happens more in colder weather or when the engine is cold. It never happens under steady state 3,000 to 4,500 rpm driving conditions. Not A/C on/off dependent. If the car is a cold start will make the popping at lower rpm’s.

No error codes and the dealer has not been able to reproduce.

Any thoughts on this would be appreciated!

 

Have you removed the coilpacks to examine them?

When they go, they have a burnt appearance.

At 100K, they're close to the end of their service life. That's where I would start.

 

I have not, but will move onto this next. Thank you!

 

The coil-on-plug units are not wear items. They don't have a specified service life or replacement interval.

Load-dependence suggests you're hearing pinging or pre-ignition. Try topping up the fuel tank with high octane gas, from a different gas station. Ideally several gallons. If the symptoms improve, you may have gotten a tank of bad gas. That is, gasoline that has been mixed with some less expensive fuel, waste oil or similar.

A spun crankshaft or connecting rod bearing is possible. Look for sparkles or a pearlescent sheen to your motor oil.

Ball bearings can make a periodic chirp or pop when they've failed. Most of the engine accessories use sealed ball bearings. The A/C compressor (noise would go away with A/C off) and transmission (noise would go away when stationary with clutch pedal pressed) use oil-lubricated ball bearings. Again, look for sparkles or pearlescence in the transmission oil.

 

I have a similar issue,but the sound gets louder when the a/c is on .

 

What about the serpentine belt tensioner pulley bearing? Not electrical, but could make similar noises as described.

 

Check the shield on the catalytic converter.