Engine Speed Drops While Coasting

[Superteeth]

I am new to these forums, so let me start off by saying hello to everyone. I have a question about my 2012 Infiniti G37 Coupe (7AT). When I am coasting (in gear) at about, say, 55 miles per hour, and let off the accelerator to decelerate without the brakes, and then lightly tap the throttle when I hit about 50 miles per hour (1500 RPM), the engine speed quickly drops to 1000 RPM and stays around there until I stop. This happens at other speeds as well, but I know the exact numbers for 50 miles per hour. I noticed this while coasting down a hill (while in gear) while driving to work today, and found that I could re-create the issue by doing the above. Obviously at 50 miles per hour the car is in 7th gear, so how does the engine speed drop even more past that? Is this normal operation, or is something wrong? Thanks in advance for any responses.

[nissangirl74]

Throttle position issue, maybe? It's a 2012. Take it to the dealer and have them check it out for you.

[Superteeth]

I do not believe that it could possibly be the throttle position sensor, if that is what you are saying. There are far too many things that do not match (for example, my gas mileage is the same even though this is happening, the car idles normally, accelerates normally, and responds properly to full throttle). The issue I have is not even really a problem, and is not something that happens very often unless I intentionally re-create the conditions. I just thought it was odd behavior, and was curious as to what was causing it. Thanks for the response, though.

[jmann]

I have the same model as yours, with the sports package. I suspect what is happening during these times is that the torque converter unlocks allowing the engine to spin at idle speed. I could be wrong about this.

[Superteeth]

1000 RPM is not the normal idle speed. However, I had a feeling that it could be something to do with the torque converter. But I thought that the torque converter locking decreases the engine speed, so when it unlocks it would increase the engine speed? Could you possibly try to reduplicate the engine speed drop in your car? Thank You.