Intermittent engine vibrations on acceleration

TREVOR ANALO

MEMBER
2004 TOYOTA CROWN
2.9L
V6
2WD
AUTOMATIC
110,000 MILES

Hi from Kenya,

I have the car listed above it is the Royal Saloon V6 with 68,000 miles, 110,000 k km, that vibrates upon acceleration. The vibrations are violent, and start with a shudder/jerk at low rpm. You can over come the vibrations by aggressively pressing on gas. Now, what is interesting, the vibrations violent to an extent that you feel you really cannot drive the car, sometimes just disappear, and the car runs smoothly like there was not a problem to begin with. Now this could go for a few weeks, and then the violent, hard vibrations and thumps come back. It is not a wheel balancing issue as the problem can be felt on the engine. When the engine vibrates, and you let go of the gas, it stops IE; there is no vibration when coasting, or driving at very high rpm. There is also another issue I have noted, somehow the engine oil runs out very fast, in a month or two I have had to re-fill twice. I switched to synthetic oil from regular, and then noticed this problem, alongside the vibration, which started a bit earlier. Any advice would be highly appreciated. Thanks.

1 Reply

KHLOW2008

MECHANIC
41,814 POSTS

Hi Trevor,
The vibration is most probably due to engine misfiring as per symptom described.

When engine ages, either due to increased mileage or time, it would always result in increased engine oil consumption. How much oil the engine consumes would depend on the extend of wear or deterioration of parts and also the oil grade and quality. Some aged engines do not take to synthetic oils and especially more so if the grade is of a higher viscosity.

Other areas of oil consumption are seals, seals for external components would be visible but for the valve stem seals, the oil would leak into the engine and be be burnt in the combustion chamber or expelled out via the exhaust manifold.

Oil leaking via intake valve seals into the combustion chamber would foul up the spark plugs with carbon build-up.

Start with a check on the spark plugs and related components to rectify the problem with the misfiring. As to the engine oil, change to a lower viscosity grade to see if it makes any difference. Synthetic oils are not recommend for aged engines that had previously been using mineral based oils.