[dpkelly]

Ok well here's my take on the noisey "diesel" engine we have in our vans. I think the intake manifold was not designed properly for our engine and it was rushed into production. The noise gets louder as the throttle opens more while driving. As the throttle closes, the noise decreases. When the engine is cold, the FITV (fast idle thermo valve) is still open which changes the shape and resonance of the intake manifold.

Now the 5th gen accord which has the F22B1 and F22B5 engines has what's called the intake air resonator control system. When the RPM's are at midrange (2900-3700rpm), the intake air begins to flow through the intake air resonator and is placed in parallel with the intake manifold. If we had something like this for our vans, it probably wouldn't be so loud.

The following diagram is of the accord intake. The Odyssey intake, I'll post in the next post.

BTW, I bought mine used from a Honda dealer and they installed a cotton baffold on the underside of the hood.

 

[dpkelly]

And here's the Odyssey intake manifold diagram.

I was thinking of checking the intake manifold for leaks, etc. since it is an older van and it's been knocked around alot since 1995. Some seals may have loosened over time. I was even thinking of opening up the resonator cavity to place a sheet of metal with some holes inside the further reduce the intake manifold noise. The resonator cavity is like a muffler for the intake manifold. I'm not sure if the bumper needs removal for this feat though.

You can read more about intake manifold design here:

http://auto.howstuffworks.com/question517.htm

 

[dpkelly]

Wow. This is an old thread. I have another idea no one thought of. When I replaced my timing belt myself, I didn't line up the counterweigth shafts properly. It vibrates and sounds kind of diesel like. You might want to check this out too. Good luck.