It's sound like a big turbo spoling up. When I let off the accelerater while in gear it makes a long whisling sound as the rpms drop. Does other rotary engines do this, or could this be the transmission? It's sounds like the engine is making the sound. Any help would be appreciated.


91 na
(mods) intake,
S-AFC,
exhaust

 

Sounds like your intake, same thing happens on my Explorer.

 

Do you mean something like the air filter is not on all the way. But it only doesn't while in gear, I can rev the engine up, and it doesn't make the sound. On the S-AFC it as a Deceleration air flow correction, but this is what it saids in instruction manual.

Engine revving higher then the Ne2 point will not have deceleration correction. When you go to the next page it saids setting (Ne-point) and Ne2 is 2000 RPM. What are they talking about? The setting tips are THR Setting : While the engine is cold and the transmission is in neutral, set the unit to a point lower than the throttle position Ne2 point can control.

Next it saids NE1- NE2 setting :while the engine is cold and the transmission is in neutral, set the unit to a point lower than the air flow % usage a value that NE1/Ne2 engine RPM can control.

Any help would be appreciated.
91na
intake, exhaust, S-AFC

 

mine does this too. But it comes from my transmission. I am about 90% positive it is my throw-out bearing.

 

mine does it also. And Im looking into my tranny soon. I would guess that its the same thing.

 

isnt that just the noise it makes when engine braking??
how loud is the hiss because most cars make a kind of a hiss noise when engine braking or gearing down same thing