Idle RPM

Hello

I noticed something curious on my 2021 Sequoia, thought I'd ask here.

When it's stopped in Drive: the RPMs show around 500. That's surprisingly low, but cool. But when I shift to Neurtal - the RPMs go to around 600. That's strange to me.

In the past I noticed (on older cars with automatic transmission) the engine idled at a higher RPM when it was in Drive vs Neutral. And that seemed natural.

Does someone know the technical explanation for this?

Thanks in advance.

 

What you are experiencing with your truck is expected.

When in drive, the engine is "driving" the torque converter, which is hydraulically coupled to your transmission/transfer case/driveshaft/axle/wheels. The output shaft of the torque converter is being held by the brakes. The torque converter serves as the loose coupling in your driveline and thus, will drag the engine RPM down.

On modern vehicles, idle RPM is entirely ECU controlled, so you can even see behavior on some vehicles where idle RPM is increased if the AC compressor is on. The Tundra/Sequoia have an integrated ECM that controls the transmission and engine from one box, and thus, you get a more "synergistic" system this way.

 

Check your battery... My 07 hovers in the 500s when I drain the battery.. Once its fully charge it should be around 600 to 700 rpm.. Neutral should jump to 1k to 800 rpm...