Rough Idle: A/C compressor?

[meangreen94z]

IDK where you got 185k from...but I only have 105k.
When I take care of my Tranny mounts, Flex disk, Center mount and Subframe bushings this Thanksgiving, I'll give the mounts the business as well
Just to clarify, this is only a vibration issue which doesn't affect the driveablity or engine components, correct?

Sorry, I thought it said 185k in your video. If the vibration is only felt at idle and the car is otherwise running fine(no SES light) then yes this is your likely cause. It shouldnt adversely affect anything if theyre just worn/sinking, although in one situation the stud was ripped out of mount. Nothing had happened in that situation either though(but could have)

[Hornung418]

Okay so I can put this to rest for now! Thanks for your help Meangreen! And welcome to bf.c! Glad to have another BMW Tech with us

[28firefighter]

I've been having this issue at well - idles roughly when the driveline is engaged (automatic transmission). Also, after stopping for about 30 seconds after driving, the RPM's dip and the car shakes a bit more than it goes back to just the ordinary slightly rough idle.

I'm planning on having the engine mounts done later in the fall, but what is this transmission software update you speak of? Is there something I can point the dealer to? Also, is there risk to having them do this since my car is out of warranty?

[telijah]

What are the RPMs at when it's idling rough? Sometimes when it's dipping too low for just a few moments and then corrects itself, you may just need some regular maintenance things such as new plugs.

[28firefighter]

Alright a little update here based on some toying around I did.

If I keep the A/C off, this issue more or less disappears entirely. With the A/C, at a stop light, the idle is much rougher and occasionally it sounds like the A/C is kicking on or off and puts a load on the car, causing it to dip or violently shake.

I can also, interestingly enough, mimick the shake/RPM dip if I turn on my xenon headlights.

Thoughts?

[28firefighter]

Bump.

Also when I'm at a stop with the a/c on, it seems as though it kicks on and off a lot causing the dip shake regularly. What would be making the a/c do this everytime I come to a stop?

I don't know if its related but if I turn the snowflake off, the dip disappears entirely but at that point I can feel an almost tick or click from the engine through the brake pedal, but nothing audible.

Again no codes ing thrown. HELP. I'm going to have the mounts and vanos checked by the mechanic on Friday. If I call the dealer regarding the software, is there a bulletin I can point them towards?

[newtoe46]

There was a DME reprogram bulletin that was to help eliminate fluctuating idle, especially with high load (ie. seat heaters on, ac on, power steering under load.) Do you have a rough idle or a fluctuating idle?

Did this also affect the m54b30? Mine does this as well and when I move the steering wheel back and forth. Any more details on the software update like firmware version? bulletin or date ranges?

Edit: After seeing this over at besiansystems.com

"Overall loss of torque and power, particularly in the lower RPM range, < 3k. Bogging then surging at 3k RPM. Uneven power distribution and RPM transition. Engine hesitations in the lower RPM range, < 3k. Louder idle and intermittent idle RPM hiccups. Difficult takeoffs. Loss of power and bogging when AC on. Increased fuel consumption. Vanos fault codes.
Double vanos cars with the M52TU engine (98/99-00) experience cold weather cold start idle jolts and possible stall."

I will buy them before I spend 100 bucks on a ecu reprogram at the dealership. That's exactly what I am experiencing. just purchased the besian seals and will report back once it has been done.

Bump.

Also when I'm at a stop with the a/c on, it seems as though it kicks on and off a lot causing the dip shake regularly. What would be making the a/c do this everytime I come to a stop?

I don't know if its related but if I turn the snowflake off, the dip disappears entirely but at that point I can feel an almost tick or click from the engine through the brake pedal, but nothing audible.

Again no codes ing thrown. HELP. I'm going to have the mounts and vanos checked by the mechanic on Friday. If I call the dealer regarding the software, is there a bulletin I can point them towards?

This is normal. It is just equalizing the system.

[28firefighter]

This is normal. It is just equalizing the system.

Is it normal for it to be shaking the car so violently when it does it?

Here is a list of my symptoms based on things I've done to try and diagnose.

With Climate Control ON, Snowflake ON:
- Rough base idle at stop light when in gear
- RPM dips that shake the car violently every 45-90 seconds
- Barely audible ticking sound, but felt through brake pedal from the engine compartment.
- Marble sounding rattle from the engine compartment on acceleration

With Climate Control ON, Snowflake OFF:
- Rough base idle at stop light when in gear, but less intense relative to above.
- Barely audible ticking sound, felt through brake pedal from the engine compartment.
- Marble sounding rattle from the engine compartment on acceleration

With Climate Control OFF ENTIRELY
- Idle issues are almost gone, but somewhat present (could be engine mounts?)
- Very clear rattling from the engine compartment that sounds like marbles rolling around on acceleration

Hopefully this helps explain the issue a bit more.

[newtoe46]

Is it normal for it to be shaking the car so violently when it does it?

Here is a list of my symptoms based on things I've done to try and diagnose.

With Climate Control ON, Snowflake ON:
- Rough base idle at stop light when in gear
- RPM dips that shake the car violently every 45-90 seconds
- Barely audible ticking sound, but felt through brake pedal from the engine compartment.
- Marble sounding rattle from the engine compartment on acceleration

With Climate Control ON, Snowflake OFF:
- Rough base idle at stop light when in gear, but less intense relative to above.
- Barely audible ticking sound, felt through brake pedal from the engine compartment.
- Marble sounding rattle from the engine compartment on acceleration

With Climate Control OFF ENTIRELY
- Idle issues are almost gone, but somewhat present (could be engine mounts?)
- Very clear rattling from the engine compartment that sounds like marbles rolling around on acceleration

Hopefully this helps explain the issue a bit more.

No it's not normal for that to happen. The snowflake button turns the a/c compressor on and off. thats why it doesnt happen when you turn it off. If you haven't done VANOS seals I suggest you do so. before going any further you will benefit regardless

[28firefighter]

I took it to the mechanic, and he seems to think that the fluctuation is normal for the compressor kicking on and off, but I'm just feeling it more because the engine/transmission mounts are shot. That is where he wants to start, so we'll see what happens after that.

What could cause the A/C Compressor to cycle every 45-90 seconds? Unless thats normal and what he is saying is correct.

Also, I saw above someone asked about RPM's....it'll idle around 650-700rpm for a base idle, and when the compressor kicks on/off it'll drop to around 600-625 for half a second and recover to 650-700 as before.

[newtoe46]

I took it to the mechanic, and he seems to think that the fluctuation is normal for the compressor kicking on and off, but I'm just feeling it more because the engine/transmission mounts are shot. That is where he wants to start, so we'll see what happens after that.

What could cause the A/C Compressor to cycle every 45-90 seconds? Unless thats normal and what he is saying is correct.

Also, I saw above someone asked about RPM's....it'll idle around 650-700rpm for a base idle, and when the compressor kicks on/off it'll drop to around 600-625 for half a second and recover to 650-700 as before.

While searching for a 330ci one of them did not fluctuate when i turned the a/c on and off. I noticed it had a new Alternator, and the vanos seals were probably not shot.

[newtoe46]

UPDATE: Welp, after 20 miles on besian seals there is no more Dip on turning on the A/C and there is a much smoother idle down transition along with power and torque delivery then before! Should get even better once I go past 200 miles on them. Thanks besian systems!

[28firefighter]

This is promising to hear. Just wish I could do them myself - Never worked on a car before, and live in an apartment so not sure I can take this on.

[danewilson77]

very nicely played Newtoe...............Great to hear. VANOS is the key for a lot of stuff.

[newtoe46]

very nicely played Newtoe...............Great to hear. VANOS is the key for a lot of stuff.

thanks, The old seals were way beyond shot. I could wiggle the piston inside the bore a good .5 to 1mm... Therefore, the oil was just shooting past the seals like water down a waterfall.The besian seals went in nice and tight and I could even hear vacuum when I moved the pistons by hand,

This is promising to hear. Just wish I could do them myself - Never worked on a car before, and live in an apartment so not sure I can take this on.

Sure you can, all you need is a basic socket set a, 19mm wrench, a good torque wrench and a set of metric torx and allen bit socket sets. Also a scalpel like razor blade or just a regular razor blade along with carb cleaner. and tons of shop rags.

[28firefighter]

Sure you can, all you need is a basic socket set a, 19mm wrench, a good torque wrench and a set of metric torx and allen bit socket sets. Also a scalpel like razor blade or just a regular razor blade along with carb cleaner. and tons of shop rags.

Thanks for the vote of confidence. Problem is I park on the street and have not so much as changed my oil before. I'm not really sure this is something I want to undertake myself, either. Flip side is, so far every mechanic I've spoken to refuses to touch it. May be one of those things I need to just live with for now.

[newtoe46]

Thanks for the vote of confidence. Problem is I park on the street and have not so much as changed my oil before. I'm not really sure this is something I want to undertake myself, either. Flip side is, so far every mechanic I've spoken to refuses to touch it. May be one of those things I need to just live with for now.

I see, It may not be viable for you to do it on your own then. Now, If you're ok with traveling to Sterling, VA we could meet up at http://www.ditymechanics.com/ and I could do it for you on the cheap side. Much cheaper then any mechanic.

[humured]

hi, did you ever get your problem fixed. Having the same issue with my M43 exactly the same symptoms. Any clues!!!

IDK where you got 185k from...but I only have 105k.
When I take care of my Tranny mounts, Flex disk, Center mount and Subframe bushings this Thanksgiving, I'll give the mounts the business as well
Just to clarify, this is only a vibration issue which doesn't affect the driveablity or engine components, correct?

[CityHunt3R]

How did you update the software?