06-04-2020, 07:32 PM | #1 |
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M240i B58 Rough Idle ONLY with A/c engaged
I get stutter and shake with Air Conditioning on. Idle without A/C on is totally stable/flawless.
Dealer claims it's normal. I don't think that's accurate. Anyone else with a B58 experience shitty idle/vibration with A/C on. Just ordered new spark plugs to see if that helps, but I only have 17k on them (original plugs, car is almost brand new. I am tuned but the car idled like shit even on the stock tune before and power gains. The stutter isn't AWFUL, but, it's noticeable and quite honestly unacceptable on a vehicle of this price. |
06-04-2020, 07:59 PM | #2 | |
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06-04-2020, 08:10 PM | #3 | |
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06-04-2020, 08:16 PM | #4 |
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Reach out to the field rep in your area , try BMW geniuses and if no resolution send a letter to BMW corporate. The car is under warranty. Ask the dealer to try turning A/C on in a few other 240s with you in the car. Even better, just show up and ask a salesperson for a new unit test drive. Then get the service manager to sit in both cars and have that person come up with an explanation. The other way to go is trying a different dealer service department (unless you are in Tucson as there's only one there).
Last edited by raddoc; 06-04-2020 at 08:18 PM.. Reason: add a sentence |
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06-04-2020, 09:07 PM | #5 |
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M235i here and my car does the same thing. AC on, feels like a cammed V8 at idle. AC off, might as well be electric. Don't know if it's normal or not but it seems like it may be common at least.
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06-04-2020, 09:28 PM | #6 |
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Heavy torque converter spinning and pumps in the automatic running and the car in Drive, heat soaked motor, cooling fans running, A/C compresser running, mechanical water pump running, and air/water intercooler electric pump running. That's a ton of load on a motor at idle. Plus the M sport cars run stiffen engine mounts.
My guess is it's a factor of the two pumps running intermittently. I rent a crap ton of cars for work and most I've rented, both mid grade and lower end luxury makes can have fairly noticeable vibration on a really hot day and the a/c and fans running while the car is in Drive. Does it vibrate when the car is in neutral? |
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06-04-2020, 11:11 PM | #7 | |
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Same issue in neutral. I sit in park and get a butt massage sometimes. It's hit or miss. Usually, it's bad. On rare occasions, it's not an issue and is smooth as butter. Something isn't right. I have multiple owners reporting similar issues on Reddit. I can understand a small difference with AC on, it puts a load on the engine, but, it shouldn't be making the car pulsate like a 20 year old vehicle. Unacceptable in my opinion. I'm a BMW fan, and this makes me never want to buy one again. I hope the dealer steps in and fixes my car or exchanges it. |
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06-04-2020, 11:13 PM | #8 | |
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Thanks for your input. Multiple people have given me the same feedback, that it runs like crap with AC on. Others have reported to me that there's no difference in operation between AC on and off. Something has to be up with my car. If every single B58 ran like this it would be a flaw within the motor, but, it's not. It's a common issue apparently but not widespread enough to have a recall or "program" in place. I will be following up with BMW corporate if Chapman BMW in AZ cannot fix it, and keeps claiming that they cannot feel any vibration/pulsating. Hell, I'll leave my car there for a week if it means they can detect it. Separate issue, their "master tech" claimed he couldn't hear ANY rattles in the car when my steering column was rattling like a snake. I have it on video/audio recording. On our test drive together, he claimed he heard virtually nothing, while I heard it rattling crazy the whole drive! Amazes me. I can live with plastic rattling here and there, but, my steering column rattles EVERY time I'm on the freeway. Master tech claimed he can't hear a clearly audible noise, and they need the guy above their master tech to have a listen. Fortunately, he isn't in until this COVID thing settles down. Wasn't aware they need multiple people to hear a blatantly obvious rattle, let alone fix it. Sorry to make this a paragraph, but, I saw XutvJet mention all the systems put a load on the motor, especially with high heat. This happens in 60 degree weather, and 110 degree weather. Last edited by brandonfrancom2; 06-04-2020 at 11:22 PM.. |
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06-05-2020, 12:54 AM | #9 |
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Hmmmm ...I just went out for a drive in my M235 6mt. 78 degrees and very humid out. Got the car really hot and turned on the AC and sat at idle. There's definitely vibration coming through the body with AC compressor and condenser fan running. I can feel the vibration in my seat, floor board, arm rest, and especially the shifter. Seems normal to me. I can't say I've ever owned a car where I can't feel the AC running at idle, especially an automatic.
When I turn the AC, the vibration goes away. I've this car since new for 4.5 years. Do you have any tuning or exhaust mods? |
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06-05-2020, 10:55 AM | #11 |
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06-05-2020, 11:39 AM | #12 | |
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Will check into the coolant. Car is brand new practically 17k miles, so I would hope it's not that already, but, it could be. If I cannot find an issue with it I will tell the dealer to look into that. Thank you! Any others experiencing my issue please drop an experience below, the more the better my case of getting the dealer to take me seriously. I already got TONS of replies on a few Reddit threads, which will help immensely. |
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06-05-2020, 04:48 PM | #13 | |
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ONCE it demonstrated the symptoms you described. On a particularly hot day of driving around, with AC on max setting, the car sat parked for brief period, on startup, with the AC on full blast, the idle felt "noticeably irregular", not sure what to say but it has never happened again since. However, we havent had many hot days yet to try to replicate the situation and test it out. |
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06-05-2020, 07:20 PM | #14 |
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It could be the compressor itself.
This car has variable displacement compressor and it can run shitty at time. (swash plate in the compressor may not work properly while it tries to adjust the displacement) |
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07-01-2020, 07:19 PM | #15 |
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2017 m240i manual and have the same issue with the stutter but not so much the shake. I’m in GA so it’s been pretty hot lately. I assume the inconsistency was due to engine load coupled with the heat. 17k miles.
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07-02-2020, 12:38 AM | #16 |
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My 2006 330i (N52) does the same, as does our 235i (N55) occasionally. Despite these engines being exceptionally smooth, once they're all loaded down with the accessory systems going, there's little that can be done to smooth them out, apart from increasing the idle.
As you add more and more load to an idling engine, at some point it requires more and more "idle torque" and since we're talking idle speeds, each combustion event is spaced out pretty far (time wise), and each needs to be pretty strong to keep the engine running under high load... this of course translates into vibration. Just the radiator fan pulls enough power to put a load on the engine via the alternator, now imagine all of the car's systems going. It's offputting yes, but the engine mounts are somewhat squishy as it is, imagine how soggy everything would be if they made the mounts even softer to reduce NVH- then you'd have customers complaining about how soggy the drivetrain is on their $50,000 performance-oriented BMW. Everything is a tradeoff, including raising idle speed. And about raising idle speed- I am not familiar with the modern BMW DME's, but just adding 50-100 rpm to your hot idle should help quite a bit, if that is possible, and if you're even willing to start modifying the DME of a car under warranty. |
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