Hey, is ist normal to hear a pusing vibration? I have a 87 gxl, its in great condition with 85k. however i was driving today, around 40 mph (2500rpm) and when i kept the speed constant and i heard a deep bass sounding reonation, pulsing about 2 times a second. It wasnt very loud, but it sounded central and right around where the engine is. I supose however it could have been coming through the shifter from the tranny?? sorry new to rotaries, is this normal?
any suggestions?
thanks

 

i've got an 88 convertible, i do notice in fourth and fifth around 2-3k mine seems to make heavy vibration, too, i never thought to worry about it though.... i can't help but say that i think it's just your engine complaining that your not giving it the gas that it want's... these things just want to go faster and faster...

 

Are you sure its not a exhaust leak.

 

im not sure its not exhaust leak, except that its a repeting periodic resonance and not a constant sound. Im not really worried, ive just never heard anything like it (has the deep vibration of shifting into a gear to low) wondering if it might have to do something rotary specific

 

Well, the only thing i can think of that would cause a deep pulsing sound is the exhaust.

A leak in the area of your catalytic converters would make noise from right underneath the car.

Here's my experience i had that sounds similar to yours as well. Whenever i would cruise with my foot light on the throttle and my revs between 2-3. I would get a very noticable pulsing coming from the exhaust out the mufflers almost like i was lightly pumping the throttle back and forth with perfect rhythm, when i was holding the gas perfectly steady. Ended up being my o2 sensor had failed or was failing and the ecu was switching back and forth from leaner/richer air fuel ratio causing the pulsing exhaust tone. The o2 sensor is only used at idle and light throttle, so when i stepped on the gas a bit more the problem went away.

If that sounds familiar you can check it quite easily by just unplugging the o2 sensor and seeing if the problem goes away. The ecu detects no signal and then defaults to rich settings, which gave me a constant tone at cruise. When it happened to me there was a very uniform fluctuation of tone, that always was about the same speed, and only cruising at light throttle.

Hope that helps.

 

^werd .. both an exhaust leack and a failing o2 will give you that pulsing noise as if youare passing light poles with your window down ... and it will usualy only happin in the taller gears 4th and 5th ,,, atleast thats what i have also found

 

your valve timing is off, get a tune up



(just kidding)

 

yeah, kinda like your exhaust bearings sound outta sync

 

its the tranny.