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N52 random rpm surge at idle.
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10-10-2019, 03:08 AM | #1 |
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N52 random rpm surge at idle.
Hi all, I've got an issue than I've been putting up with but am now ready to fix it as I'm taking the car on a long 8hr trip this Friday!
When stopped, the rpm will drop about 150-200 rpm then spike back up, this causes something to rattle. Not sure if the rattle is related to the rpm or if its something loose and just rattling when the rpm drops. The rpm drop is very annoying. the rpm jump is not huge. with idle at about 700, it'll drop 200 then go right back up to 700 No issues while driving and no SES light. I'm going to change the plugs tomorrow and clean the vanos solenoid. Anything else I should look at? I haven't found a thread describing my exact issue. Thanks.
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E70 X5 35i M Sport-Stage1 Tune. Alpine over Black E91 328 M Sport-Alpine over Black-Alpine over Saddle brown. E93 335i-DINAN tuned. Alpine over Saddle brown Last edited by Serf27; 10-10-2019 at 03:15 AM.. |
10-10-2019, 09:34 AM | #2 |
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Is it the AC turning on maybe? Some level of drop is normal when that happens. However that seems like too much. I would indeed start by looking at the VANOS. Also check the oil filter cap for missing parts (causing low oil pressure, there are multiple threads explaining this issue).
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10-10-2019, 12:04 PM | #3 |
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I’ll look into the oil cap. I had never heard of this! Thank you.
I know the ac drop you’re referring too and this isn’t the case. The rpm drop will happen the whole time I’m at idle waiting, not just once. It will go down-up-down-up maybe stay still for a second then back down and up. |
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10-11-2019, 03:16 AM | #5 |
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Thanks for that.
However I don’t have time to do the PCV right now before the trip. Today it hardly did the surging, it was colder though than the last few days. I saw another thread that describes similar issues that lead to a coil being just bad enough to lightly stumble but not throw a code. I will embark on my trip with a few spare coils and hope for the best!
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E90 335i-408WHP. Alpine over Terra brown
E70 X5 35i M Sport-Stage1 Tune. Alpine over Black E91 328 M Sport-Alpine over Black-Alpine over Saddle brown. E93 335i-DINAN tuned. Alpine over Saddle brown |
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10-11-2019, 07:29 AM | #6 |
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Did you look at the codes ? I would start by plugging in INPA or ISTA to get some readings from the shadow errors and looks at the 'smoothness' test before throwing parts at the problem randomly.
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10-11-2019, 09:08 AM | #7 |
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I hooked up bimmer geeks ProTool which is near the same as inpa for reading shadow codes isn’t it?
No codes popped up at all. Besides transmission fluid quality. |
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10-11-2019, 11:54 AM | #9 |
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I had this same issue and solved it by removing and cleaning the vanos solenoids. It's a really common problem since oil builds up in and around the solenoids. They are very easy to remove and clean and shouldn't take longer than 30min
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10-11-2019, 11:55 AM | #10 |
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Drives: 2011 E90 328i//1995 E34 530i
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04-02-2024, 10:59 PM | #11 |
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Hey any luck with a fix for this issue? My 2010 528i xdrive E60 model is doing the same thing I can’t figure out what it could be, any help is appreciated
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04-03-2024, 09:23 AM | #12 |
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Doing this on my N52 130i resolved my hot idle issues.
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