[ES_TRADER]

So this is after driving for about an hr in 100 degree heat with the A/C on. I came to a stop light and noticed the car shaking or feeling rough at idle.

I know the car was warmed up and also noticed that the engine temp was 2 notches to the left of the center notch. usually its sitting at one notch to the left but not two.

Pulled the car into the garage and didnt shut of the car. AC was on but i was turning it on and off as i taped the video. The rpms were bouncing between 600-1000. Definitely felt vibration in the seat. car is 2011 335i.

Most of the abnormal idles came when AC was on but i would get a surge in rpms to 1000 when i shut the AC OFF. weird.

Any ideas before i hit up the dealer next week?

No cel

sorry long video but u have to watch it carefully to see it..happens every 20-30 secs or so.

[apache335]

A little rpm changes at idle seems normal, but if the car is shaking, bring it in for service. Could be ignition coils, fuel pump etc.
Had my share of these issues with my 2007 335i. Now have 2012 335is and trouble free for 13ks.

[ES_TRADER]

im afraid dealer going to waste my time and tell me cannot duplicate. any other thoughts? i drove the car again yesterday but this rpm bouncing did not occur

[kkakonn]

Same problem with my n55 as well. A few times it rev'd up to 2k and scared the crap out of me.

[N55]

Before my Traded in my N55 it did the same exact thing.

[Juiced46]

Completely normal. When you turn the A/C on its going to bump the idle up a tad. The slight fluctuation and the feeling you are getting is because the A/C compressor clutch is turning on and off. There is nothing wrong with your car.

[Yeoman]

Originally Posted by Juiced46

Completely normal. When you turn the A/C on its going to bump the idle up a tad. The slight fluctuation and the feeling you are getting is because the A/C compressor clutch is turning on and off. There is nothing wrong with your car.

^^This

[ES_TRADER]

Originally Posted by Juiced46

Completely normal. When you turn the A/C on its going to bump the idle up a tad. The slight fluctuation and the feeling you are getting is because the A/C compressor clutch is turning on and off. There is nothing wrong with your car.

Is it wierd that it only did this odd fluctuation one day? And also the engine temperature gauge wasn't in the middle after driving all day long?

I know the AC on will increase idle a bit but mine was jumping up and down a lot that day. By several hundred Rpms.

Normal when AC on I see rpm bump up by 50 rpm

[Juiced46]

Originally Posted by ES_TRADER

Is it wierd that it only did this odd fluctuation one day? And also the engine temperature gauge wasn't in the middle after driving all day long?

I know the AC on will increase idle a bit but mine was jumping up and down a lot that day. By several hundred Rpms.

Normal when AC on I see rpm bump up by 50 rpm

The engine temp doesn't always have to be in the middle. All depends on ambient conditions, obviously driving will keep it cooler and stop and go or beating on the car will make it run hotter.

Not really odd that it only happened one day. Your video shows nothing abnormal going on. Was it ever worse then this? Looks like it was really hot your dash is showing 104*, the A/C may just have been working harder that day that is all.

Does it ever happen with the A/C off?

[ES_TRADER]

Originally Posted by Juiced46

The engine temp doesn't always have to be in the middle. All depends on ambient conditions, obviously driving will keep it cooler and stop and go or beating on the car will make it run hotter.

Not really odd that it only happened one day. Your video shows nothing abnormal going on. Was it ever worse then this? Looks like it was really hot your dash is showing 104*, the A/C may just have been working harder that day that is all.

Does it ever happen with the A/C off?

It was 104 and normally when it's that hot my temp gauge will be one marker to the left of midpoint. Always that way. That day I noticed the rpm bounces I also noticed that my temp was way to the left to be normal.

I've seen it one marker to the left even on 60 degree mornings.

After driving 20 mins its always one hair to the left of center.

That day I drove for about 2 hrs straight in hot heat and the temperature was 2-3 markers to the left of center so it was signaling it was cooler on a hotter day. Odd

Also I got the rpm bounces a few times during cold starts. Bounces up and down a bit before settling down.

Normally when I turn the AC on it rpm usually doesn't move. If it does Incan barely feel it. That day it was surging and would surge when I turned the AC OFF. Not on.

[dr335is]

Originally Posted by Juiced46

Completely normal. When you turn the A/C on its going to bump the idle up a tad. The slight fluctuation and the feeling you are getting is because the A/C compressor clutch is turning on and off. There is nothing wrong with your car.

I disagree...
The compressor does not turn on/off every 15 sec, and at the constant rate.
These are not "small" fluctuations.
And, as the OP pointed out, the other day the phenomena was gone...

I have never seen anything like that, my AC is on 100% of time and in the summer, we've had 100+ degreed every day...

[Juiced46]

Originally Posted by dr335is

I disagree...
The compressor does not turn on/off every 15 sec, and at the constant rate.
These are not "small" fluctuations.
And, as the OP pointed out, the other day the phenomena was gone...

I have never seen anything like that, my AC is on 100% of time and in the summer, we've had 100+ degreed every day...

You are correct it doesnt cycle every 15 secs. However the OP stated he was manually turning it on and off which will cause it to kick on.

[ry335]

I have the exact same problem on mine. This happens all of the time, and I live in a very hot climate. The AC has nothing to do with it. That was my first though, so I tried driving around for a while with it off and it did not make a difference.

I saw a thread in the N55 section and somebody reported there is a pending software update to solve the issue.

[ES_TRADER]

Originally Posted by ry335

I have the exact same problem on mine. This happens all of the time, and I live in a very hot climate. The AC has nothing to do with it. That was my first though, so I tried driving around for a while with it off and it did not make a difference.

I saw a thread in the N55 section and somebody reported there is a pending software update to solve the issue.

Do you think it has something to do with the thermostat?

So odd that I got this issue when the needle was dead center after the car was fully warmed up.

All my other cars are just fine. This one is the only one that acts funny

[ES_TRADER]

I got the rpm surge up to 900 when I shut the AC OFF. The rpm increase should come when AC is turned ON. But not by a few hundred rpm. The dealer told me its supposed to be 50rpm increase, at least on my 328 at the time a while back

[chrisk03]

Get the same thing sometimes on my N55. Noticed mostly with the AC on when it happens and not sure if ever happened without it on. I believe one time I shut the AC off and it stopped "bouncing". It actually just happened today, but once I start moving, it seems to be fine and the RPMs settle into "normal".

I just had my car in for service and forgot to mention, as it honestly is pretty rare and really didn't bother me, so would love to know if there actually is a SIB out there for this issue and a software update.

[dr335is]

Originally Posted by ES_TRADER

So this is after driving for about an hr in 100 degree heat with the A/C on. I came to a stop light and noticed the car shaking or feeling rough at idle.

I know the car was warmed up and also noticed that the engine temp was 2 notches to the left of the center notch. usually its sitting at one notch to the left but not two.

Pulled the car into the garage and didnt shut of the car. AC was on but i was turning it on and off as i taped the video. The rpms were bouncing between 600-1000. Definitely felt vibration in the seat. car is 2011 335i.

Most of the abnormal idles came when AC was on but i would get a surge in rpms to 1000 when i shut the AC OFF. weird.

Any ideas before i hit up the dealer next week?

No cel

sorry long video but u have to watch it carefully to see it..happens every 20-30 secs or so.

So, was this occuring as you were turning the AC on and off (every 20 sec) or, you're implying that you had the AC on or off and the same thing was happening?

[Thp4]

My N55 does this sometimes too. On one occasion a couple of weeks ago, it stuttered like it was going to cut off and then the RPMs shot up to 1000 before settling back down. I scanned codes and 31E9 showed up. I cleared it and reset adaptations and issue has not reoccurred.

[ES_TRADER]

Originally Posted by dr335is

So, was this occuring as you were turning the AC on and off (every 20 sec) or, you're implying that you had the AC on or off and the same thing was happening?

I was turning the AC on and off every 30 sec or so in the video. The bouncing came when the AC was on but the surge to 1000 came when AC was pushed off. Then returned to normal.

But prior to me actuating the AC button, I would feel The car shuttering at the stop light while AC was ON. And I saw the bouncing of Rpms.

It was when I got in my garage that I decided to test the button on and off while shooting video

[Bleep]

If it only happens when you turn the AC on or off that's totally normal since you're putting more load on the engine and it takes the car a moment to acclimate itself. As to why you only recently realized this you probably simply didn't pay enough attention. It happens to just about every car when you turn on/off the AC.

[ES_TRADER]

Originally Posted by Bleep

If it only happens when you turn the AC on or off that's totally normal since you're putting more load on the engine and it takes the car a moment to acclimate itself. As to why you only recently realized this you probably simply didn't pay enough attention. It happens to just about every car when you turn on/off the AC.

I understand that this happens when I turn on the AC but in my case it started jumping around. None of my other n55s do this.

In the video u can see its abrupt here and there. Also today I went for a drive and turned the AC on. There was no change in rpm whatsoever. Did it many times and no change in rpm.

That day I shot the video rpm bounced and I felt the car shake

[benzo23]

Sometimes when im low on gas too i get a little rpm shake...