I have a 2014 QX80 with about 110k miles that experiences a engine vibration at low RPM and wanted to see if others have experienced similar issues and what was the cause.
I've done a bit of servicing on the vehicle recently hoping it just needed some love but thus far, the vibration continues.
* Walnut blasted intake valves (new intake gaskets used)
* Replaced plugs with OEM
* Replaced fluids in entire drivetrain
* Trans service (cleaned the pan, replaced the filter and replaced the fluid multiple times with OE Type S)
* Used some Lucas fuel injector cleaner
* Some other stuff I'm probably forgetting about
I connected my OBD diag tool and there are no error codes. I did notice a downstream 02 sensor is responding slowly and falls about 0.1v for a while after a manual (2k)RPM change - it slowly recovers and follows the other bank VO. I'm waiting on a new o2 sensor but this got me thinking that perhaps I have a blocked catalytic converter. I just ordered a backpressure tester to verify.
I also noticed that the idle is a bit erratic going from 650~ to 850~ within the course of 30 seconds somewhat continuously. When the idle is in the 650-700 range, the vibration disappears and reappears once the idle is higher. The IAC program was executed after the walnut blasting.
There is no misfire reported. The engine sounds healthy - just loud ticking from the HPFP.
At this point, the only thing I can think of is a blockage in the exhaust or perhaps a MAF sensor but the MAF seems to be responding correctly to RPM change. Again no codes (stored or pending) to indicate any of these issues. It could be motor/trans mounts but since there are moments of no vibration, I doubt this the root cause.
Any additional suggestions of what it could be are greatly appreciated!
Thanks for reading.