The Volvo is the Nordic model 440 GL, same as here. I have experienced this vibration earlier only in 1-2 gears with 1-2k rounds. Now I am able to experience it with no gear. My friends are suggesting the change of timing belt (
"jakopäähihnan vaihto") and the change of spark plug (
'sytystulpan vaihto'). According to the Finnish site:
2.0- moottori on taasen FENIX-3B monipisteruisku -- 2,0 litran koneissa on ollut ainostaan Zenith,in ja Solex kaasuttimet ja 2.0 on ns.uudemmissa myöskin ollut vaihtoehtoisesti Bosch,in nelipisteruisku.
Which translates to (from Google Translate):
2.0 engine was again a FENIX-3B monipisteruisku - 2.0 liter engines has been the only Zenith, Solex carburetors, and in 2.0 and has also been alternatively so called newer Bosch's nelipisteruisku.
Which means that the Volvo with 2 liter engine has some FENIX-3B/Bosch injection thing. I don't know how reliable information this is. It is the same car as here, my other friend said that it may not be due to spark plug but blocked exhaust as well. I am not sure where to start debugging this vibration. I have noticed an increased use of fuel so hence doubting the spark plugs.
How should I diagnose this vibration? And which can cause this kind of vibration?