2019 Honda Fit - Rough idle

The car idles roughly when I stop at a redlight. What is going on?

Is there a check engine light on? if so most Autoparts stores will scan your vehicle for free. then you can post the codes here to get better help.
there could be many reasons for a ruff idle. a few are bad spark plugs, coils, vacuum leak, bad gas.

Many possibilities, but you might ask your shop to check for a vacuum system leak. Wouldn’t usually cause a symptom at higher engine rpm & loads , but the extra air in the mixture results in an overly lean idle mixture. Shop might want to do a fuel trim test as well.

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For that year Fit, does the manual suggest any valve clearance adjustments? Our Fit was unfit until we finally did that.


OP’s Fit is fairly new, 3-4 years. @GorehamJ , was your Fit in similar age-bracket when valve clearance problem discovered? I guess it varies by engine design, but seems surprising to see a valve clearance problem develop on a 2019. By way of comparison, I do valve clearance measurements on my 30 year old Corolla every 4 years; while clearances on some of the valves steadily creep towards the limits over time, so far all the valves have always measured ok, no adjustments required.

Why are automobiles still being built without automatic valve adjusters?

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  1. Why do men people climb mountains?
  2. Why is there air?
  3. Who put the ram in the Rama Lama Ding Dong?
  4. Why do dogs lick their Balls?
    Oh, the wonder of life’s questions!
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Answer to your fourth question: Because they can.


Probably some design issue which fails and causes issues.

No chance of a collapsed lifter problem occurring under warranty, and resulting arguments w/customers, might be a motivation for a manufacturer to choose a non-hydraulic lifter design. It doesn’t seem like the cost difference would be the motivation. My 50 year old truck uses hydraulic lifters, 30 year old Corolla non-hydraulic, neither has given me any lifter trouble so far. I guess in retrospect of my diy’er experience, I’d say I prefer the hydraulic type simply b/c I’ve never had the need to measure the valve clearances on those.

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Compare the rpm limit for each engine. Solid lifter engines maintain precise valve operation at high operating speeds.

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My 1999 Honda Civic has solid, adjustable lifters; also a forged crankshaft. I think that goes back to Honda’s heritage of motorcycle engines that can run at very high RPMs.

I adjust the valves every few years. Always some have drifted from the spec. The idle seems better afterward, but I admit there could be some psychology along with the physics.