Burning Odor After Engine Is At Operating Temp. - Corolland: the Toyota Corolla Forums

Recently had the 1998 TC LE repaired: valve cover gasket, brakes front and back and power steering pump. Everything is fine up to when premium fuel was added to a half tank of mid grade fuel. A burning odor developed about 8 miles from fill-up. I am taking the vehicle in for an inspection for fluid leaks possibly related to recent repairs or maybe a new problem. However, is it possible that the premium fuel is not combusting well enough to cause the odor and a power loss? A recent safety inspection deemed all OK after the repairs; but the odor is a cause of concern. What do you think?

Highly doubt that the high octane is the cause here. Higher octane doesn't resist combustion, just moves the self-ignition temperature to a higher point, a spark will still ignite the air/fuel mix, even if you were running 120 octane race gas. More likely, it is cleaning solvent or pooled out that might be causing the burning odor.

What sort of odor is it - burning smells like melting plastic, burning oil, gasoline smell, etc.?

Temporary smells are normal as the new brake pads bed in. There may also be some residual oil, etc on engine or exhaust manifold from the repair process which should burn off. Check to see and confirm that the leaks are fixed.