[AttaboyK]

Hi All,

I'm new here and really hope someone knowledgeable can help. I will keep this as brief and concise as possible.

Car: 2011 BMW 535ix

Problem: Rough Idle @ low rpm; Engine misfire codes; roughness disappears after foot on gas but reappears once slowed down to lower engine speeds (approx. 1000rpm or less); Very very rarely I get drivetrain malfunction warning but that always goes away once I restart car and doesn't return until say next 2-3 months.

Troubleshooting so far: Changed all spark plugs and ignition coil. Changed air filter. Intake valves blasted in case any carbon build-up, close to none but cleaned anyway. Fuel injector cleaner. (all of which was done by experienced & professional mechanic).

Still getting misfire codes and rough idle persists (sometimes more aggressive than other times). Noteworthy that she drives perfect once I gas down - shakiness only reappears when I come to a full stop or drive really slow (i.e. coast without my foot on gas).

There is no sign of oil or coolant leaking. Oil and coolant levels do not deplete abnormally. Exhaust emission appears normal (i.e. no excessive smokiness).

I got an experienced mechanic to do smoke test. No leaks detected. Mechanic says I should change valve cover assembly. He thinks this is where air is leaking from as he is convinced this is all due to a vacuum leak. I don’t see any visible cracks on valve cover and this part + labor is quite expensive. Before i change any more parts, I just want to at least ensure it'll get rid of this problem.

What do you think could be causing this rough idle @ low rpm & misfires? Do you think he’s right about valve cover? Do you think the O2 sensor could have anything to do with this? Or even worse, the Injector (despite having used injector cleaner)? Are there other tests that can help identify culprit before any more $ is spent?

[gervais]

I'm having the exact same issue. Have done the same general BMW maintenance things. I've connected to ISTA+ and can see the misfires happening. They are sporadic and are not linked to any cylinder. I've gotten the "Drivetrain Malfunction" error on iDrive twice. The 2 times I've gotten the "Drivetrain Malfunction" indication, it was immediately following start up nd the car ran ESPECIALLY rough. Shut it down, immediately restart - much smoother, no "Drivetrain Malfunction" and back to a miss here and there. No "shadow codes" when connected to ISTA+, no check engine light - even with "Drivetrain Malfucntion" light illuminated in iDrive.

I'm a bit stumped. Currently, I am leaning toward a PCV issue (or just an air leak in general) as yesterday when I was entering traffic with the car cool (oil gauge basically on cold - coolant around 120 degrees I heard a high pitch whine from the engine bay. On start up it sounds whiney as well - but not sure if that is just normal for these (haven't had the car long).

Finally, it may be worth noting that my car was CPO and I have all dealer service records up to ~70k. Currently has ~100k.

Recent Maint:
Plugs (OE, Bosch) less than 500 miles
Walnut blast
coolant flush
Intake gaskets
reset adaptations

TIA

[tcabill]

PCV is integrated into the valve cover. There are plenty of vids out there on how to test if the diaphragm has ripped. There are repair kits available on Ebay but they are a little sketchy.

[equ]

For me (at 50k), it was a spark plug, even though they had been replaced at 40k.

[gervais]

Originally Posted by gervais

I'm having the exact same issue. Have done the same general BMW maintenance things. I've connected to ISTA+ and can see the misfires happening. They are sporadic and are not linked to any cylinder. I've gotten the "Drivetrain Malfunction" error on iDrive twice. The 2 times I've gotten the "Drivetrain Malfunction" indication, it was immediately following start up nd the car ran ESPECIALLY rough. Shut it down, immediately restart - much smoother, no "Drivetrain Malfunction" and back to a miss here and there. No "shadow codes" when connected to ISTA+, no check engine light - even with "Drivetrain Malfucntion" light illuminated in iDrive.

I'm a bit stumped. Currently, I am leaning toward a PCV issue (or just an air leak in general) as yesterday when I was entering traffic with the car cool (oil gauge basically on cold - coolant around 120 degrees I heard a high pitch whine from the engine bay. On start up it sounds whiney as well - but not sure if that is just normal for these (haven't had the car long).

Finally, it may be worth noting that my car was CPO and I have all dealer service records up to ~70k. Currently has ~100k.

Recent Maint:
Plugs (OE, Bosch) less than 500 miles
Walnut blast
coolant flush
Intake gaskets
reset adaptations

TIA

UPDATE: I replaced valve cover over the weekend. It is noticeably smoother. Engine doesn't miss on start up and transmission even shifts smoother.
HOWEVER - it is still not smooth. It has very slight roughness still.

Generally speaking, this car is a little disappointing - the build quality of this BMW is pretty shitty. From creaks, and rattles to the slam/clunk when you hit MN potholes....The Mercedes I just came from was 10,000% better (same-ish miles, AMG, on 35 series rubber) I had an e39 m-sport iT a few cars back and that was a far better car (even though it had higher miles).

I'm definitely hyper sensitive to car related issues, but thats why I'm driving BMWs, Audis and Mercedes. I expect better from BMW. Anyone else seeing this slight roughness at idle?

P.S: I've logged on JB4 and watched sensors using ISTA+. JB4 is pretty useless for logging anything but pulls (no issues with the car when you pour the coals to it - other than hanging at the top of 3rd if you pull and let off at shift point). ISTA recorded very few misfires, even before replacing valve cover. Cylinder roughness correction values all over the board, though. I removed the JB4 for now.

[ezaircon4jc]

I don't see coils on your list...

If you're so dissatisfied just sell the car.

[bake]

Originally Posted by tcabill

PCV is integrated into the valve cover. There are plenty of vids out there on how to test if the diaphragm has ripped. There are repair kits available on Ebay but they are a little sketchy.

Can you post links to some of these tests?

[Kyngofpop]

Originally Posted by ezaircon4jc

I don't see coils on your list...

If you're so dissatisfied just sell the car.

Duly noted

[David_Vasha]

My best advice that I can offer is that if you scan the car and it lists multiple misfires, it's almost never the coils fault. Cheap insurance is to change the plugs if you haven't done so before. For myself the code for a low pressure fuel sensor was showing when I scanned the DME. It seemed like these can go bad on n54 and n55 engines sometimes. It's a relatively easy DIY. The code I got was 119201. Hope this helps.

[naCAnItihS]

Check you fuel rail pressure. I was having issues with a crappy idle that would stumble occasionally. Really aggravating. Turned out my LPFP was acting up (fluctuating pressure) causing fuel starvation at the HPFP and the pressure would dip causing it to hiccup. Replaced my LPFP and I have a nice smooth idle so far.

[OnlyGerman]

Strange. I had a slight stumble on start. Due to high mileage, it was due for plugs and coils. Replaced with all Bosch and normal now.

[David_Vasha]

Don't mean to bump up this thread OP but did you have any update on what happened? Did you get it fixed? Currently dealing with the same problem.

[AttaboyK]

Originally Posted by David_Vasha

Don't mean to bump up this thread OP but did you have any update on what happened? Did you get it fixed? Currently dealing with the same problem.

Currently in same boat as gervais . After a few recent fixes noted below, she runs noticeably smoother. HOWEVER - it is still not smooth. It has very slight roughness still. I won't go as far as calling it a "rough idle" but it's almost like she has a cough (or covid lol). But on a more serious note, RPM is steady - however there's a "pulsing" shudder/roughness every 10 seconds or so. I have also found that holding the steering/holding my foot on the brakes allows me feel it more than say if I just sat there with not contact to wheels/brakes. I actually just returned from a new mechanic today (highly rated and closer to home) who ran diagnostics and could not feel this roughness. I have a follow up scheduled and will keep you guys posted.

RECENT FIXES: Summer 2020, I noticed a very small leak (oil) thus replaced Oil pan gasket + valve cover & gasket (you probably already know this but BOTH VC and VC gasket are recommended to replace at same time because of how hard it is to get to said part(s)/ labour cost vs parts cost which is just a fraction).

Today, the attached images detail what was most recently done. I will likely try BMW TSBs (software update) soon. Updates to follow but do let me know if there's anything else you think I can help with in the interim.

Relevant Links to other issues described herein: [

] [

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[AttaboyK]

Originally Posted by naCAnItihS

Check you fuel rail pressure. I was having issues with a crappy idle that would stumble occasionally. Really aggravating. Turned out my LPFP was acting up (fluctuating pressure) causing fuel starvation at the HPFP and the pressure would dip causing it to hiccup. Replaced my LPFP and I have a nice smooth idle so far.

Thanks tons for sharing this. I did read posts whereby this was the culprit but I likely won't get to it until/if it gets significantly more prominent (i'm currently at a stage whereby mechanics don't seem to feel said intermittent roughness)

[David_Vasha]

Good luck man I hope you get it figured out. I'm on that same path right now too and it's driving me nuts. Just hit 120k miles but I've been babying her. Installed new spark plugs and coils in December hoping that it would fix the issue. It didn't. I don't really want to say it's fuel injectors since my start ups have never missed and that this car is mostly highway driven. I'm really starting to believe it's a software fluke given that it's a 2011. I guess we'll find out when I take her to the shop this summer.