Rough Idle & High Fuel Consumption

lsinko · 06-27-2021, 11:15 PM

Hi Everyone,

I have a 2005 BMW E90 330i with the N52 engine. Recently it has started idling rough and almost sounds like a misfire. It also has terrible fuel mileage - It use to doe around 9litres per 100Km now its doing 11.5L/per 100Km and keeps increasing.

I have looked at the forum and have replaced the spark plus, replaced the coils, replaced the Vanos solenoids and checked for any vacuum leaks but none seem to be the cause of the issue.

Any help/suggestions would be greatly appreciated, I am really stuck with this one!

e91Owner · 06-27-2021, 11:45 PM

I know you said you checked vacuum leaks, but did you check the PCV?

Stuiterbal · 07-01-2021, 03:57 AM

Any codes? Perhaps bad fuel injectors?

efrain61601 · 08-20-2021, 10:24 PM

see if it's ur canister purge valve. my 2006 325i n52 had a slight rough idle when cold starting and just ate up my fuel, when my gas tank got low around 30 miles of gas left a check engine light popped up and when i got it scanned my purge valve was stuck open i refilled my tank and the light went away so sometimes it can be hard to diagnose so idk if this is ur problem for curtain. the purge valve cycles fumes and emission back through ur engine so it can burn them to cause less pollution and give ur car more power, and if it's stuck open or closed it can really screw ur engine over time. i hope this helps in any way

06-27-2021, 11:15 PM	#1
lsinko Registered 0 Rep 1 Posts Drives: 2005 BMW E90 330i N52 Join Date: Jun 2021 Location: Queenstown, New Zealand iTrader: (0)	Rough Idle & High Fuel Consumption Hi Everyone, I have a 2005 BMW E90 330i with the N52 engine. Recently it has started idling rough and almost sounds like a misfire. It also has terrible fuel mileage - It use to doe around 9litres per 100Km now its doing 11.5L/per 100Km and keeps increasing. I have looked at the forum and have replaced the spark plus, replaced the coils, replaced the Vanos solenoids and checked for any vacuum leaks but none seem to be the cause of the issue. Any help/suggestions would be greatly appreciated, I am really stuck with this one!
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06-27-2021, 11:45 PM	#2
e91Owner e91Owner 425 Rep 1,129 Posts Drives: 2011 e91 & 2010 e60 Join Date: Mar 2018 Location: Out of the Office iTrader: (0)	I know you said you checked vacuum leaks, but did you check the PCV?
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07-01-2021, 03:57 AM	#3
Stuiterbal New Member 17 Rep 24 Posts Drives: 2008 BMW 335i Join Date: Sep 2018 Location: California iTrader: (0)	Any codes? Perhaps bad fuel injectors?
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08-20-2021, 10:24 PM	#4
efrain61601 Registered 0 Rep 2 Posts Drives: 2006 e90 325i Join Date: Aug 2021 Location: panama city, florida iTrader: (0)	see if it's ur canister purge valve. my 2006 325i n52 had a slight rough idle when cold starting and just ate up my fuel, when my gas tank got low around 30 miles of gas left a check engine light popped up and when i got it scanned my purge valve was stuck open i refilled my tank and the light went away so sometimes it can be hard to diagnose so idk if this is ur problem for curtain. the purge valve cycles fumes and emission back through ur engine so it can burn them to cause less pollution and give ur car more power, and if it's stuck open or closed it can really screw ur engine over time. i hope this helps in any way
	Appreciate 0 Quote