BMW 1 Series Coupe Forum / 1 Series Convertible Forum (1M / tii / 135i / 128i / Coupe / Cabrio / Hatchback) (BMW E82 E88 128i 130i 135i)


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      12-30-2018, 09:45 PM   #1
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Drives: 2011 128i
Join Date: Sep 2012
Location: South Carolina

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Need help diagnosing n52 issue. Engine shudders, seems to run rich.

Car: 2011 128i, n52 engine with 90,000 miles on it. No mods at all.

Issue: When I start the car there is a type of shudder/rumble coming from the engine. It's definitely not a misfire, it's not that jarring, but still quite noticeable. Feels like the engine is missing a beat every other second. Also, there's an extremely strong smell of gasoline. I've had the car for 7 years, and the gas smell is definitely new and far stronger than normal. Car drives normally and shudder is lessened after driving for a while.

Some backstory: Engine was leaking oil from valve cover gasket, so 4 months ago I replaced it (the gasket) along with the eccentric shaft sensor seal and eccentric shaft actuator seal. Repair went well, and car has driven fine for months since. Also worth knowing, this issue appeared about 1 day after I washed the engine bay. Certainly feels like that can't be a coincidence.

What I've tried: First checked for error codes, there are none. Then I checked for any new leaks from valve cover, everything seems fine, no sign of oil anywhere. Then I pulled a spark plug to check its condition. The plug was terribly dirty. I pulled all 6 and all were terrible, carbon was so built up it was bridging the gap. BMW claims to have replaced all 6 plugs (and coils) 30,000 miles ago (under warranty and I have the work order/receipt), but the plugs I pulled were not BMW branded (they were Denso) nor were the coils (Delphi). Apparently the dealership messed up royally or just screwed me. So I replaced all 6 plugs. Engine noise and strong gasoline smell persisted.

Questions: Should I replace the coils? Could this be a MAF or O2 sensor-type issue? Or maybe related to the valve cover gasket replacement/engine wash?

Many thanks in advance.

*Edit: After more research I'm thinking it's a fuel injector issue.

Last edited by leagues58; 12-31-2018 at 10:18 AM.
Appreciate 0
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