what causes engine drag

[7Ggalant97]

say when im driving at like 40mph or any speed and let off the gas i feel the car slowing on its own a little ,gets worse when AC is on , like im a truck driver downshifting for a hill ..im pretty sure its not the brakes, maybe i should switch to synthetic oil, but what else could cause this that i should look into ...fuel filter etc. ?

also i do feel the drag even going downhills

[seth98esT]

Its called engine braking. Unless you put it in neutral, when you let off the gas, the car will decelerate as the throttle plate is closed, the RPMs drop, and the car is still in gear. This is normal no matter what car you drive.

If you put the car in neutral and let off the gas, then you should be able to coast for a pretty good distance without slowing down too much. But if its in gear, then the trans is still engaged and the friction of everything(wheels, trans, moto, weight of the car) will cause the car to decelerate.

[9G]

yup. in the 8g v6, its horrible.

[6G72gearhead]

yup. in the 8g v6, its horrible.

especially with a 5spd, I like it though.

[WarmAndSCSI]

It means you have good compression. Your engine is nothing more than a self-powered air pump. It works during a reverse flow of energy too. The excess energy during engine braking is compressing the air in your cylinders. But if you had really low compression, you wouldn't see as much of a "drag" when you let of the throttle (unless the cylinder walls were causing frictional drag).

[7Ggalant97]

normal , ok good i was wooried cuz i didnt have this deceleration on my truck or other cars in years past that i recall