stwus

I noticed last week that I couldn’t manually upshift. I had no idea why and thought my upshift paddle shifter was broken. It only shifted above 2k or 2.5k rpm. However, this week I noticed that if I turned the AC off, the manual shifting and auto shifting are back to normal around 1.5k rpm. Is this normal when the AC is on on hot days above 80F, the engine revs at a higher rpm and shifts late at a higher rpm?

RPB81

I do believe this is the case with any car. I disabled the stop/start the other day via OBD which requires the A/C to be turned on. I noticed almost immediately the car felt bogged down and shifted differently. I enabled it again and opted to hit the button. It was not so apparent on my old AMG’s (8 cyl). I think it’s much more noticeable on a 4 or 6 cyl. The AC system is quite a burden on the engine: https://www.yourmechanic.com/article...rom-the-engine

The pros definitely out way the cons if you reside in a humid place. Especially before that big thunderstorm hits during the summer months!

synergize

That's weird, I feel no engine stress when the AC is on, in fact, this is the first car owned where the engine does not notice the AC is running.

Zed 2.0

You're trying to manually shift the car at 1,500 rpm? It wouldn't surprise me very much if the car wouldn't want to do that under high accessory load.

RPB81

Do you keep the AC running at all times? I drove the car for 2-3 weeks before turning it on for the first time. You need a good baseline before it’s noticeable.

I can assure you it bogs the car down and the loss of power is inevitable. This is the effect on a 8 cyl which is night and day to a six under these circumstances:


I’m stating facts - I would advise turning it off if need be.

synergize

[QUOTE=RPB81;25472507]Do you keep the AC running at all times? I drove the car for 2-3 weeks before turning it on for the first time. You need a good baseline before it’s noticeable.

I can assure you it bogs the car down and the loss of power is inevitable. This is the effect on a 8 cyl which is night and day to a six under these circumstances:

No, I only use it when it's really warm outside, and rarely drive during the maximum heat of the day, and it gets plenty hot in Boise, Idaho. I never know the AC is running, except for the cool air coming out the vents.

RPB81

[QUOTE=synergize;25472517]I just wanted to confirm for the OP. The answer to their question is set in stone.

stwus

Mine is actually the first I noticed that the car shifts differently with AC running. Maybe it’s because it’s too hot outside? My previous car didn’t do that...

RPB81

Every car acts differently under these circumstances. The true colors are revealed when the system is off

stwus

Yes, I only use AC when it is very hot. Otherwise, I usually only have the fan on. When the AC is on, the engine revs right below 1k rpm, without AC, it is around 600-800 rpm. So it sounds like the it's in dynamic mode the whole time with AC on. I tried to switch the drive select between Dynamic and individual (set for engine sound dynamic), and I almost could not hear the difference if the exhaust valves are all open when the AC is on or not, because the hinge is at a higher rpm, its hard to hear the difference. Also, today I noticed that after I turned the car off after about 25 miles of non-stop driving, the radiator was still running for about 15-20 seconds after I looked the door.