This problem has bugged me for a while, i have a stock 96 accord lx 4cyl and when it runs at around 2100 rpm there is some serious engine vibration, however, it is fine at all other speeds. could it be the mounts?


thanks

 

You didn't mention Automatic / Standard transmission

Has this condition existed since the last timing belt was replaced?
Can you duplicate this in neutral / park?
Does this condition exist only when driving / with the engine pulling?

If in Neutral / Park;
If it is indeed a vibration rather than a noise that you're complaining about; then I would say you're dealing with a harmonic vibration. (2500rpm is the 'sweet spot') Honda incorporated a counter-balanced / timing belt driven shaft specifically with the intent of canceling engine vibrations. If this should move from it's timed position, it would induce increased vibrations.
If driving under load:
Yes, you could have a motor mount issue. A loose / worn mount would allow the engine to move out of it's intended range and impact against another engine compartment component - thus the vibration.
Automatic accords incorporate a vacume assisted rear engine / transmission mount which can be problematic. When these fail, it will literally shake the teeth from your head. I've seen bumper covers fall off cars and also mirrors become useless from the shaking! Putting one of these failures in reverse induces metal/metal contact. Fortunately, the worst effects are felt at idle .....

P

 

It is an auto, the vibration is mostly absent in neutral (there is other vibration when the car is very cold), and i am not even sure if the timing belt has actually ever been replaced.

 

If it doesn't vibrate in neutral then it's not an engine vibration related to the harmonic balancer... Does it vibrate in all gears?

 

it does vibrate in all gears, except maybe in 4th if im on the highway, i never really notice vibration at very high speeds

 

I suspect a motor mount ? engine position issue. Under all conditions OTHER THAN Neutral / Park and D4-Lockup, the engine doesn't develop enough torque to move the engine in the mounts - thus no noise. It's only during the times of torque multiplication (accelerating thru 1st, 2nd and third) does it develop enough torque to deflect the mounts - and make noise.

You may be able to simulate the condition by enlisting a TRUSTED friend, put him / her in the driver's seat and have him / her torque load the engine* while you're outside with the hood (bonnet to some) open watching for engine movement. You might actually determine what it's resting against :-)

P

* both in D AND Reverse !!

 

Yes I would inspect the mounts....after that, if they are good.

Does this seem more rpm related than speed related? If more to rpm's then I would next inspect the inner cv joints.....next, when was the last time the egr ports (not just the valve but the ports as well) were cleaned.

 

It is definitely an RPM issue, not speed. And i Just replaced both CVs recently and there was no effect on the engine vibration.

 

im having the same issue with my boosted ls standard trans. just picked up the car last night it sounds as if the vibration is inside the motor. its bugging the hell out of me i thought it was my exhaust at first but its perfect not touching anywhere.. also when i first start my car it doesnt wanna idol untill the motor kind of seddles down. any advice? pleasee

 

X2 on plugged EGR ports, especially if it doesn't do it when the engine is cold.