RPM dip with A/C running - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

BunnyRZed · 06-11-2013, 04:06 PM

Update: TSB Fix Available

Here's the TSB download link for this issue:

Click Here

Anyone notice that when you have the A/C running and come to a stop the RPM would dip and then go back up? Dealer checked said was this was normal and all the new Subaru does it. Any thoughts?

zoomzoomers · 06-11-2013, 04:08 PM

It's not normal if it's severe and this is a documented issue with the twins. I've had the idle dip from about day 1. Bought mine in July '12. It usually goes away once the motor is warmed up, but it's embrassing to have someone in the passenger seat when the car is cold. They always ask if there's something wrong with the car.

BunnyRZed · 06-11-2013, 04:17 PM

It seems to happen only when the A/C is running and I'm coming to a stop.

NYNOMAD · 06-11-2013, 05:04 PM

With the A/C on it's normal.

Norkoastal · 06-11-2013, 05:18 PM

Not a fan of this car with AC on over 90 degree heat.. Too much of a drag to run the AC system.. Probably the main reason i'm going to add more low RPM focused mods to the car to battle this...

spyingwind · 06-11-2013, 05:23 PM

The A/C will toggle off if you floor it. Casual driving you shouldn't see or feel the A/C turn off.

If you turn on the A/C and the rear defroster at the same time it dips pretty hard, but then again you shouldn't be doing that. :P

Add an exhaust and most people won't notice a thing.

zc06_kisstherain · 06-11-2013, 06:39 PM

normal to me. most vehicles i driven, including family minivan had little RPM dip.

fistpoint · 06-11-2013, 07:29 PM

Same here, coasting to a stop sign/light in gear...when I get to around 8mph or less I put it in neutral and the dip happens.

Only with A/C on, the idle is totally stable without A/C. I do NOT think I am a candidate for the idle issue as that issue happens A/C on or off.

BunnyRZed · 06-11-2013, 08:59 PM

Sounds like everyone is saying this is normal when A/C is on, thanks.

Dalers08 · 06-11-2013, 09:32 PM

What happens (in every car) is the A/C pulls a decent amount of electricity to run, so when the engine is turning at idle it is asking the alternator to pull harder to make more power to use the A/C. In older cars or cars with weaker electrical systems (my 90 240 for example) at idle if you roll the windows down the rpm's take a dive.

whtchocla7e · 06-11-2013, 09:42 PM

What other devices run off the alternator in this car? Even though I seem to have everything turned off on the dash/console I still feel like the alternator kicks in constantly. I'd like to turn everything completely off and see if it makes a difference to my idle.

SloS14 · 06-11-2013, 09:55 PM

Quote:

Originally Posted by Dalers08

What happens (in every car) is the A/C pulls a decent amount of electricity to run, so when the engine is turning at idle it is asking the alternator to pull harder to make more power to use the A/C. In older cars or cars with weaker electrical systems (my 90 240 for example) at idle if you roll the windows down the rpm's take a dive.

I think the load on the engine itself to run the compressor is much more of the problem than the load on the electrical system.

Mikem53 · 06-11-2013, 09:58 PM

Quote:

Originally Posted by BunnyRZed

It seems to happen only when the A/C is running and I'm coming to a stop.

It happens to me too and its not the idle dip issue mentioned above.
only occurs during rpm drop to idle and the AC compressor kicks in
and drops the rpms too low, then it quickly recovers after stumbling
and then is stable..
Only when the engine is not engaged to the trans when coming to a stop.
Not every time.. but happened a few times to me under those conditions..
IMO.. Its a software glitch..
otherwise i find the idle with compressor cycling to be very smooth and
transparent in operation.
mid 90's tomorrow forecasted.. Raven in the hot sun =

Mikem53 · 06-11-2013, 10:11 PM

Quote:

Originally Posted by whtchocla7e

What other devices run off the alternator in this car? Even though I seem to have everything turned off on the dash/console I still feel like the alternator kicks in constantly. I'd like to turn everything completely off and see if it makes a difference to my idle.

The electric power steering system is quite power consuming at times..

06-11-2013, 04:06 PM	#1
BunnyRZed Senior Member Join Date: Dec 2012 Drives: BRZ Limited [37J] Location: Sacramento, CA Posts: 328 Thanks: 60 Thanked 135 Times in 87 Posts Mentioned: 27 Post(s) Tagged: 0 Thread(s)	RPM dip with A/C running Update: TSB Fix Available Here's the TSB download link for this issue: Click Here Anyone notice that when you have the A/C running and come to a stop the RPM would dip and then go back up? Dealer checked said was this was normal and all the new Subaru does it. Any thoughts? Last edited by BunnyRZed; 03-28-2014 at 12:04 PM. Reason: Add TSB Download

06-11-2013, 04:08 PM	#2
zoomzoomers Senior Member Join Date: Nov 2011 Drives: 2013 Subaru SWP BRZ Limited 6AT Location: Darkside Posts: 1,862 Thanks: 526 Thanked 305 Times in 207 Posts Mentioned: 9 Post(s) Tagged: 0 Thread(s)	It's not normal if it's severe and this is a documented issue with the twins. I've had the idle dip from about day 1. Bought mine in July '12. It usually goes away once the motor is warmed up, but it's embrassing to have someone in the passenger seat when the car is cold. They always ask if there's something wrong with the car. __________________ Man Law#17:A man in the company of a hot, seductively dressed, woman MUST remain sober enough to fight! MODS: AVO tubes + filter, Cusco (F) strut brace w/ MC brace, Perrin CBE, Subaru OEM trunk tray, Grimmspeed front license re-locator & hood struts and Beatsonic rear cam.

06-11-2013, 09:42 PM	#11
whtchocla7e Senior Member Join Date: May 2012 Drives: 2013 FR-S Hot Lava Location: CT Posts: 424 Thanks: 30 Thanked 222 Times in 81 Posts Mentioned: 0 Post(s) Tagged: 0 Thread(s)	What other devices run off the alternator in this car? Even though I seem to have everything turned off on the dash/console I still feel like the alternator kicks in constantly. I'd like to turn everything completely off and see if it makes a difference to my idle. __________________ Live to drive another day

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06-11-2013, 04:17 PM	#3
BunnyRZed Senior Member Join Date: Dec 2012 Drives: BRZ Limited [37J] Location: Sacramento, CA Posts: 328 Thanks: 60 Thanked 135 Times in 87 Posts Mentioned: 27 Post(s) Tagged: 0 Thread(s)	It seems to happen only when the A/C is running and I'm coming to a stop.

06-11-2013, 05:04 PM	#4
NYNOMAD Senior Member Join Date: Jun 2012 Drives: BRZ WRB LTD MAN Location: NY Posts: 108 Thanks: 4 Thanked 25 Times in 22 Posts Mentioned: 0 Post(s) Tagged: 0 Thread(s)	With the A/C on it's normal.

06-11-2013, 07:29 PM	#8
fistpoint Senior Member Join Date: Dec 2011 Drives: Supercharged Golf Cart Location: Estados Unitos Posts: 1,196 Thanks: 75 Thanked 364 Times in 206 Posts Mentioned: 3 Post(s) Tagged: 0 Thread(s)	Same here, coasting to a stop sign/light in gear...when I get to around 8mph or less I put it in neutral and the dip happens. Only with A/C on, the idle is totally stable without A/C. I do NOT think I am a candidate for the idle issue as that issue happens A/C on or off.

06-11-2013, 08:59 PM	#9
BunnyRZed Senior Member Join Date: Dec 2012 Drives: BRZ Limited [37J] Location: Sacramento, CA Posts: 328 Thanks: 60 Thanked 135 Times in 87 Posts Mentioned: 27 Post(s) Tagged: 0 Thread(s)	Sounds like everyone is saying this is normal when A/C is on, thanks.

06-11-2013, 09:32 PM	#10
Dalers08 Member Join Date: Jun 2013 Drives: 2001 Audi A4 Location: Farmingdale, NY Posts: 18 Thanks: 2 Thanked 11 Times in 5 Posts Mentioned: 0 Post(s) Tagged: 0 Thread(s)	What happens (in every car) is the A/C pulls a decent amount of electricity to run, so when the engine is turning at idle it is asking the alternator to pull harder to make more power to use the A/C. In older cars or cars with weaker electrical systems (my 90 240 for example) at idle if you roll the windows down the rpm's take a dive.

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