I have an IS350, and the engine sounds like a diesel engine. It has two noises. One is a "knocky" noise and the other is a "clicky" noise. I think the "clicky" noise is the solenoid, but what about the "knocky" noise? I use premium gas, so it can't be the gas. It sure doesn't sound like a G35 or BMW 330. Is this normal for IS350? Thanks.