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Discussion Starter · #1 ·
In a recent thread the discussion centered on the vibration from thec CVT transmission in drve while standing still with the brake on vs. moving the lever to neutral.

On my way to the airport Sunday to fly to Toronto I paid particular attention to the vibration from the transmission while stopped. I even compared it to going into neutral. While enroute at 39,000 ft in smooth air I paid attention to the vibration I was feeling in my coach seat arm rest compared to the vibration I felt in my Accord's console arm rest. This was one of American Airline's brand new Airbus A319 aircraft. The vibration from my CVT transmission was about the same as on the Airbus. Both were very smooth.
 

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I've concluded that its nothing to do with the cvt but everything to do with the engine idle speed. My idle speed without extra electrical load on it is too low. Once I turn on the fan or the headlights, the idle is boosted (to run the alt more I assume) and the vibrations are gone.

Do you always have a power accessory on such as the fan or headlights?
 

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When the engine is cold it idles pretty fast. The car almost wants to take off when it's still cold when idling at a stop light. Until the engine gets just above the C, it's rough.
 

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Discussion Starter · #4 ·
I've concluded that its nothing to do with the cvt but everything to do with the engine idle speed. My idle speed without extra electrical load on it is too low. Once I turn on the fan or the headlights, the idle is boosted (to run the alt more I assume) and the vibrations are gone.

Do you always have a power accessory on such as the fan or headlights?
I checked out the vibration with the engine completely warmed to normal operating temperature. I had the AC on in the auto mode. The idle RPM was less than 1,000 RPM.
 

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I noticed this a while back too.... A way to get rid of that vibration in drive is to turn on the rear defroster. But who wants that running 24/7?


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Discussion Starter · #6 ·
I noticed this a while back too.... A way to get rid of that vibration in drive is to turn on the rear defroster. But who wants that running 24/7?


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This vibration is so minuscule that I had to concentrate to feel in the car. I had to also concentrate to feel the same amount of vibration on the airplane, which has no reciprocating parts to my knowledge. If your car is vibrating that much at a stop that you have to go to neutral than the car has a problem and needs warrantee attention from your dealer.
 

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I checked out the vibration with the engine completely warmed to normal operating temperature. I had the AC on in the auto mode. The idle RPM was less than 1,000 RPM.
The vibrations that I am specifically talking about go away too when my ac is on. Do you always have your climate control on when driving?
 

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I noticed this a while back too.... A way to get rid of that vibration in drive is to turn on the rear defroster. But who wants that running 24/7?


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Do your vibrations continue with the headlights on? For me I just have turn something on that uses a moderate amount of power such as headlights or the fan and the vibrations go away. Im sure the defrost, which requires a lot of power will do the same for me.

In fact, with my headlights on I dont see a drop/rise in the tach when I shift between neutral and drive. When all the accessories are off though I can see the tach move when I shift between neutral and drive.
 

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Do your vibrations continue with the headlights on? For me I just have turn something on that uses a moderate amount of power such as headlights or the fan and the vibrations go away. Im sure the defrost, which requires a lot of power will do the same for me.

In fact, with my headlights on I dont see a drop/rise in the tach when I shift between neutral and drive. When all the accessories are off though I can see the tach move when I shift between neutral and drive.
Not sure about headlights. Def gone with AC. I forgot if it goes away with just the climate control fan only.


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Any electrical load you add will cause the engine to idle slightly higher, hence reducing vibration. Also when the engine is cold it'll idle higher to get the cats up to temperature (for emissions).

Neutral, for the "old" AT was 800-850 RPM. D, with no accessories, can drop to 650 RPM and you get some pretty annoying vibrations. Turn on the fan or whatever and the idle goes just high enough to make vibrations less.
 

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I had owned two different 8th gen 4-cylinders that had this very same problem. It was very annoying. It seemed the origin was vibration from the engine which caused something in the rear of the car to resonate. Letting off the brake or putting in neutral would make it go away. My 9th gen does not have this issue, no matter what the electrical load is, and it idles just under 1000 RPMs while in drive after being full warmed up. Must be luck of the draw.
 

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Any electrical load you add will cause the engine to idle slightly higher, hence reducing vibration. Also when the engine is cold it'll idle higher to get the cats up to temperature (for emissions).

Neutral, for the "old" AT was 800-850 RPM. D, with no accessories, can drop to 650 RPM and you get some pretty annoying vibrations. Turn on the fan or whatever and the idle goes just high enough to make vibrations less.
The problem is that a few of us are experiencing these fatiguing vibrations while others arent. I can confirm our 8th gen also has a noticeable drop in rpm from neutal to drive but the vibrations are well tamed. The vibrations in the 8th gen are not enough to induce excursion on the front seats as they do on the 9th gen.
 

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When the engine is cold it idles pretty fast. The car almost wants to take off when it's still cold when idling at a stop light. Until the engine gets just above the C, it's rough.
I just realized something--with the LED headlights on the Touring, because of the lower power consumption, there is no weird electrical behavior! Ever! :jawdrop: (I know that headlight flicker was a common 8th-Gen problem, particularly the first couple years.) Even running with the defogger, lights, and A/C, the wipers don't even slow like they would do on past Accords thanks to an overworked alternator and too-small battery.

As for engine idle, I learned quickly about the fast idle on the V6s when I first took a non-NAVI Sedan for a test drive--and went twenty feet before I knew what was happening! :eek: (Thankfully, nobody was walking in front of the car, and the salesman who was with me wasn't ticked-off!) You have to have your foot FIRMLY planted on the brakes when you drive off or back out of the garage! :yes:

Thank you, emissions regs! :rolleyes: (Engine has to run hard to light-off the front catalytic-converter on cold-start.)
 
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