Engine Whistle (1 Viewer)

[Rolocado]

I've made an interesting observation about my LX when I am pulling onto an on ramp on the highway. When I start accelerating from a turn to the ramp, the engine changes tones around 25-40 mph from a normal engine exhaust to an almost whistle as it speeds up. I recently changed both exhaust manifolds so I know that is not the issue. Is it just the engine putting more fuel in? I would record the sound if I could but it would be muffled by wind. I can only hear it with the drivers window down and I can't hear it from the cabin otherwise.

 

[hoser]

The stock muffler has a spring loaded flapper valve that opens up under pressure. Perhaps that is what you are hearing?

 

[Live to Ski]

Did a little "poking and hoping" w/r to the fj100 having an egr valve. Looks like it does.

May not correlate, but I had the exact same symptoms on my 60: due to egr valve sticking open. Whack with screw driver handle closed it. Ended up bypassing egr function by plugging vacuum lines. NOTE that this may cause fuel mixture issues with resulting burnt valves/smog problems.

Just a shot in the dark.