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Honda Accord Engine Vibration & Noise @ 1500 RPM

Hi, I have a 2012 honda accord 4-cyl engine, automatic transmission with 71K miles. For the 2-3 past months, I have noticed a vibration and low humming noise at around 1500-1600 RPM. It is present when maintaining this RPM and worse when under load. The vibration and noise go away when accelerating past this RPM and when I put my foot off the gas pedal. The issue is not present when going 1500 RPM in neutral and is not speed/gear dependent. Also, no check engine light is on.

I was told the engine mounts were worn and has 3 of them replaced but the problem is still there. The shop who did it noticed the same problem. But said since there is no code there is nothing they can do. It seems to get better if the car does not sit cold for long. Like running errands. But is most noticeable before going to work and after.

Not sure what the issue is, any ideas?

What happens when you notice this problem, speed up a little until it gets better, then shift to neutral and coast back down through the same speed? Manual or automatic transmission?

It is an automatic transmission. I speed up a little or let my foot off the gas and the vibration and noise stop.

when did you change your transmission fluid last time?

Not sure if it has ever been changed. Bought it from my friend not long ago. The transmission fluid is a brown color with a red tinge to it.

then before you spend more, make yourself a service and do a fluid change.
you may be surprised with results… or not… but it is definitely needed.
you have to use Honda OEM fluid, as this brand is picky on ATF type

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Update: The transmission fluid was changed but the problems are still persisting. Should I be worried about it if no engine light is coming on?

Yes you should be worried, as you are. No codes can’t fix is so disappointing. So many could bes, do you think it might be engine related, throttle body cleaning or fuel issues come to mind.

What about making these tests:

#1. get to the speed and load where vibration is present and turn off the “overdrive” on the transmission selector. It will keep the speed and the load, but will change RPMs, is problem still there?

in this test, I would seek to check if problem is connected to CV joints, not transmission

#2. if you keep “overdrive” off and get vehicle to the RPMs where problem happens, but at a different speed not, is problem still there?

this one targets engine and torque converter in transmission

also, just “out of the blue” guess: check if harmonic balancer on the engine has some strange wobble or visually off center or rubber is getting cracked, here is a reference picture:

do you get the noise and vibration when idling at 15-16K rpm?

Don’t you mean 1.5-1.6K
I don’t know of any car engine that can even reach 15,000 RPM, even at WOT. :smiley:

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I had it checked out at a Honda dealership and they noticed the issues but could not pinpoint the cause. It seems to be somewhat temperature dependent. The warmer weather seems to make it less noticeable.

No, only when the gas pedal is being used

oops, yes I did

The vibration occurring at a constant speed, but going away upon acceleration could be there’s too much play somewhere in the drive-train. My first suspects would be the CV joints and the transmission’s differential. It’s more difficult to test the differential, and as long as the transmission hasn’t ever been low on fluid, the differential is less likely; if you decide to pursue this further, suggest to start with a check for abnormal play in both half-shafts.

If the problem is the differential, the most likely cause is some problem w/ the transmission fluid. You’re using Honda’s transmission fluid right? Stuff from a Honda dealership? Don’t use aftermarket transmission fluid, as Honda’s automatic transmissions are very particular about the fluid specs.

F1 engines wind up to 20,000 RPMs. You probably mean street cars, though.

Update/Additional Notes: As the weather warms up it seems to be vibrating less violently. However, I left it sitting for 3-4 days and the vibrations were considerably worse.

Any idea what could cause the temperature dependence?

Besides what was already said, I do not know what could be causing the vibration under different conditions. Here is a link that might help understand some other causes.

I have the same problem with a Honda Crv 2014 awd. 2.4-liter engine and 5-speeds automatic transmission. Vibrations seeming to come from the engine between 1500 and 1600 rpm under load. The vibrations are absent at the lower and higher rpm. I believed that it could come from spark plugs because I have 150,000 km. The vibrations are always present after having changed thems. When the vibrations occur, one has the impression that they are engine misfires but no code. I also notice a certain vibration when stopped when the transmition is engaged. That made the belt tensioner snap that I changed to 120,000 km. It snaps less but still snaps.

Sfor my bad english.