[richie_s]

Random thread, but my throttle response seems to change a lot. Sometimes, my car flies like a dream with just a tap on the gas pedal, while other days, I feel like the car actually slows down when I shift up even though I use the same pedal input as normal. Of course, it's probably a really subtle difference, but driving stick lets you notice these subtle issues.
Someone suspected the A/C for being in charge of it...
But I thought A/C bogging a car down was a thing of the past.. I thought only old cars or cars with tiny engines had that issue

So is my throttle response just related to my A/C? I usually have it on at all times, but my throttle response changes from fast to sluggish in a matter of minutes

[n55x3]

You can definitely feel the A/C compressor cycling. And it definitely puts a parasitic drag on the motor which causes reduced performance. I can feel the strain every time the compressor cycles on. It annoys me so most of the summer I run with all windows down and no A/C on. Only when I have passengers do I roll the windows up and run the A/C.

[floydarogers]

Originally Posted by richie_s

...
But I thought A/C bogging a car down was a thing of the past.. I thought only old cars or cars with tiny engines had that issue.

The ECU will cause the A/C compressor to disengage if you use full throttle (or perhaps less than full, but the limit's high.)

Don't forget that turbo cars are pretty sensitive to heat - that's why we have an intercooler. The knock sensors, in concert with the temperature sensors in the intake tract keep things from knocking, but the result is a loss of power. It's summertime, hot air means more chances of retarded timing. Could be other things, too.

[richie_s]

Interesting.. You learn something new everyday

[Safety2213]

I drive a manual and find that the car is much more moody than my previous e46. I also find that driving the car in sport mode feels more linear and direct than comfort. Try to see if it makes a difference. I don't notice a difference when I run ac but then again I don't drive aggressively.

[BeachsideF30]

Ill definitely take the lag in performance over sweating in this torturous summer weve been having lol.

[richie_s]

Originally Posted by BobbyP

I drive a manual and find that the car is much more moody than my previous e46. I also find that driving the car in sport mode feels more linear and direct than comfort. Try to see if it makes a difference. I don't notice a difference when I run ac but then again I don't drive aggressively.

Funny you say that. I hate driving in sport mode on a regular basis because when I switch back to the default comfort setting, I feel like I'm driving a Prius

[gomichaelkgo]

Originally Posted by n55x3

You can definitely feel the A/C compressor cycling. And it definitely puts a parasitic drag on the motor which causes reduced performance. I can feel the strain every time the compressor cycles on. It annoys me so most of the summer I run with all windows down and no A/C on. Only when I have passengers do I roll the windows up and run the A/C.

Our cars have a variable angle swashplate compressor, which reduces drag on the engine under open throttle or when cooling demand is low. Do you ever feel that the AC is never truly "off" even if the indicator light is not lit? This is likely why.

And, a study was done that showed open windows decrease fuel efficiency vs AC at speeds above 35MPH. Since aerodynamic drag scales with the cubic power of velocity, going twice the speed causes 2*2*2=8 times the drag on your car at 70 MPH than at 35 MPH. With a variable angle swashplate, increasing the engine RPM will reduce the compression stroke distance under constant cooling demand.

I never open my windows on the highway.