RPM patterns?

[jtmann]

Just bought an 07 Camry LE. Great car. Runs quietest and smoothest of any mid size sedan I've driven. Question for the forum re: do these RPM patterns seem normal:

1. When she is first started (i.e., cold - live in Canada) she revs when idle (ie parked) at around 1,250 - 1,500. Shortly thereafter she'll drop to 1,000 and shortly after that to 750. For the rest of the ride she'll RPM at 750 when idle (eg at a stop light), which seems right to me. Does this pattern seem right to you?

2. When she is cold/just started, when I turn the heater on it increases the RPM by around 100-200 (eg if she was at 1,000 heater will spike it to 1100-1200). But after a while driving the heater does not seem to have impact on RPM. I assume this is normal - ie the spike in RPM at first is becase the engine is cold and she needs to rev up to produce heat, whereas later when the engine is warm it does not need to spike?

Seem like easy questions but wanted to ask anyway

Thanks!

[GT-R]

Seems normal to me.

RPM also goes up a little when you turn your wheel left or right.

[thrawnis]

This is all normal.

[ScrooYoo]

yep. Normal for a Toyota, which are famous for low end torque. Not so normal for other types of cars like Infiniti or turbo Audis that like you to really rev the engines to get the torque. One of the first things that surprised me when I got my camry was when I was on the highway going close to 100mph and the tachometer was barely above 3000rpm. At the time I thought it was crazy for a 4-banger.

[Redline_Me]

Originally Posted by GT-R

Seems normal to me.

RPM also goes up a little when you turn your wheel left or right.

And when the AC is working, plus a slight vibration.

[GT-R]

Originally Posted by Redline_Me

And when the AC is working, plus a slight vibration.

Yes I hate that!

[Redline_Me]

Tell me about it. I never use my AC unless its important that i dont sweat at all. Just cuz of what it does to the engine.

[tengiday]

Originally Posted by Redline_Me

Tell me about it. I never use my AC unless its important that i dont sweat at all. Just cuz of what it does to the engine.

Correct me if I'm wrong. I can think that when the AC is on, heat is removed by conduction and convection. An evaporator which is cold absorbs the heat from the air that is passed through it and then cold air is forced out through the vents inside the car by the blower motor. This is done by pressurizing refrigerant with a compressor and then releasing refrigerant inside the air conditioner evaporator.
Many people tell me that running the AC will consume more gas, and running the heat will not use gas. I don't know if this is true. Could anyone have any idea? Thank you!

[olympicgold]

Originally Posted by tengiday

Correct me if I'm wrong. I can think that when the AC is on, heat is removed by conduction and convection. An evaporator which is cold absorbs the heat from the air that is passed through it and then cold air is forced out through the vents inside the car by the blower motor. This is done by pressurizing refrigerant with a compressor and then releasing refrigerant inside the air conditioner evaporator.
Many people tell me that running the AC will consume more gas, and running the heat will not use gas. I don't know if this is true. Could anyone have any idea? Thank you!

@OP Your RPM issue is perfectly normal.

AC cold and heat both consume about same amount of fuel as far as I know

[Frodo65]

Originally Posted by tengiday

Correct me if I'm wrong. I can think that when the AC is on, heat is removed by conduction and convection. An evaporator which is cold absorbs the heat from the air that is passed through it and then cold air is forced out through the vents inside the car by the blower motor. This is done by pressurizing refrigerant with a compressor and then releasing refrigerant inside the air conditioner evaporator.
Many people tell me that running the AC will consume more gas, and running the heat will not use gas. I don't know if this is true. Could anyone have any idea? Thank you!

A/C compressor is using engine power (directly, in the 'plain' Camry as the compressor is driven by a belt, or indirectly in the TCH where the A/C compressor is electric, and the engine has to generate the electricity). So, A/C can be clearly shown to consume a noticeable amount of power - most likely a 2-5 HP at 'full tilt'.

Heater is not using engine power except to turn the fan (generated electricity there); the heater is using 'waste' heat from the engine. As such, the heater won't have a easily measurable power and FE impact. The TCH is something of an exception, as the heater will cause the ICE to run more when the temps are cold and you're idling, to keep ICE temperatures in the programmed zone. At highway speeds, this won't be the case, as the ICE has to run anyway, and the heat is 'free'.

So, for the 'regular' Camry, A/C will likely give you a .5-2.5 MPG 'hit', with no 'above the noise' hit for heat. The TCH will see a hit for both A/C and heat due to compressor power consumption and increased ICE run time when you're running heat and in stop-and-crawl traffic.

[workerant]

Originally Posted by Redline_Me

And when the AC is working, plus a slight vibration.

Increase RPM = Increase vibration. It's normal.

Originally Posted by GT-R

Seems normal to me.

RPM also goes up a little when you turn your wheel left or right.

The defroster too increase the RPM. And while the window is rolling down or up also increase RPM a bit.

But the one thing increase RPM the most is the gas paddle.

[Redline_Me]

Both of the last two posts all true.

That's good info for the OP, Frodo.