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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > Mechanical Maintenance: Break-in / Oil & Fluids / Servicing / Warranty > Diagnosing rough idle



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      05-13-2019, 12:56 PM   #1
unk045
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Diagnosing rough idle

Gentlemen,

In using Carly to run diagnostics, I received codes 002A7C, 0029D2, 0029D0 and 0029CC which are VANOS intake cold start, misfires on cylinders 6, 4 and 'several cylinders' respectively.

I cleared all the codes and I removed both solenoids and cleaned them with MAF airflow sensor cleaner, blew into them after to dry and let them also sit for over an hour to dry and swapped the intake and exhaust solenoids.

The car runs a tad rough on start up, in that you feel the car vibrating a little while in the driver seat. She's good on power and acceleration and smooth while driving. When you're on the throttle for maybe a couple minutes or so while standing and then let the car get to idle after being on the throttle, the idle is slightly rough and you feel the vibration again. When you do a warm restart, you feel the vibration and the rough idle then too. To be fair, I don't know if all this was really happening before or if the cleaning exacerbated the issue slightly or even caused all this.

Long story short, since the cleaning of the solenoids my FRM fried (not saying they're related at all), but it has been replaced by BMW and in re-scanning with Carly, I now got codes 002F83 and 002F81, both of which show as Motorabstellzeit, time counter combi - time counter DME, comparison. The reason I mentioned my FRM failure is I thought these codes may have been related to the failing of my FRM....but then again I should've walked away with BMW resetting all my codes.

Some people have also commented that 002F83 and 002F81 could be related to a weak battery, but I've checked my battery using a multimeter after almost a couple days of no use and it's showing at 12.4V. Some people have also said solenoids can trigger those 2 codes, but they've already been cleaned...not to say the solenoids still can't be bad.

After the FRM replacement, I've tested my coils and in unplugging all 6 the engine would run rough so the coils seem ok and the coils and plugs were changed slightly over 20k miles ago now.

The good news is the coils seem ok since Carly didn't give me a code again for misfires or the vanos solenoids for that matter. The bad news is I'm still left with this rough idle issue. However, I would like to caveat that since the FRM replacement when all the codes should've been cleared by BMW, I only drove about 20 miles before I ran my second Carly diagnostics to give 002F83 and 002F81 so it may not have been enough time/mileage to trigger the solenoid or misfire codes.

Could it be that I just need to replace my solenoids or is there something else going on?

I know this was a long one so thank you for bearing with me.
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      06-26-2019, 02:07 PM   #2
unk045
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I thought I'd follow up on my post should there be someone out there struggling with this issue. It seemed to have been an issue with my MAF. I removed the MAF and while it didn't seem dirty to the naked eye, it did clean it with MAF cleaner and installed back. Didn't notice any idling differences upon installation, but in starting the car a few days later and idling while driving does seem smoother now.

Still reminiscences of the issue, but it is better.
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      06-27-2019, 12:36 PM   #3
mastarron
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I think its been proven that cleaning the VANOS solenoids buys some temporary time for some people, but if you got solenoid codes being thrown, then you need to get those swapped. Theyre an easy DIY, so id start there.

You said your battery is reading 12.4v. Im assuming this is when the car is off? What is the reading when the car is on?

Do you have a video of the rough idle?

Personally my rough idle was taken care of by replacing spark plugs and coils. I then had a "weird" idle for a LONG time, and I was finally able to get it down to the alternator pulley. The annoying idle and idle noise went completely away. But the rough idle of my coils being bad vs the bad alternator pulley, are night and day difference. The pulley was more of an annoyance, while the coils made me worry about the car because of how much it would shake (it felt like my motor mounts were gone).
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