I was curious to know a technical question about the Scion's transmission, or if it applys, the engineering of the conventional transmission itself. I have noticed that when I am breaking from say about 50-60 mph and I put the car on neutral, as I am slowing down the rpm needle slowly floats above the 1k mark. Sometime it will reach up to 1.5 to 1.7k until I get slower and it settles to idle revolution.

Does this have anything to do with the synchronizers preparing for an anticipated downshift? Does this affect gas mileage? Does it have to do with the ratio of wheel spin and the transmission carrying "left over" torque? I would of researched this on google but it seems our fellow scion drivers could explain it better than an average engineer. Feel free to be technical and nerdy, I'd really like to know.

Thanks

 

i've seen that in other manual transmission cars. It's not just a toyota thing. I believe it's because of the ram-air effect. As the car is up at that speed, 50-60mph the air is flowing into the engine regardless of what you're doing to the gas pedal.

The air is still coming in, the MAF (mass air flow) sensor sees the extra air coming into the engine and matches it with the right amount of fuel, when it does this you see the rpm's come up. The transmission was in neutral so the computer only looked at the demand from the air flow. As you slow down the engine will come down to idle (no more air flow input into the engine).

There isn't any left over spinning with the gears in the transmission this is all the engine computer evaluating what's going on. Hope that helps ya.

 

x2 on the ram air, our engine bay has lots of way of getting air into it and at speeds its enough to be pushed into the intake which inturn makes our revolutions go up due to maf readings...get used to it, and no ur gas mileage wont suck chances are you prob drove an auto before the tc...if u notice auto cars idle at 1k sometimes even above....while stick idle less

 

I used to drive a 97 Miata before the tC. When I put the car on neutral no matter what speed it was in the rpm would drop to idle. In addition, the comparison to engine response time was faster on the Miata. I'm guessing because it had smaller revolving parts (1.8L). But while on the topic of idling speeds if an auto and manual are at a dead stop why would the auto idle higher than the manual?

 

long to explain just does..

 

I think the auto idles higher because it has to in order for the torque converter inside the auto trans to build pressure (hydraulic) for it to be able to shift the gears by itself.

And I think if you were to look at the miata it probably had a MAP sensor, if it didn't have an actual "live" air flow sensor (MAF, Mass Air flow) but was estimating based on the MAP (manifold absolute pressure) sensor then that might be why it went to idle and didn't fluctuate.