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General E46 Forum
This is the place to get answers, opinions and everything you need related to your E46 (sedan, coupe, convertible and wagon) BMW!

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Old 04-26-2016, 03:25 AM   #1
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Join Date: Aug 2015
Location: London
Posts: 67
My Ride: '00 e46 330ci
Random misfires - Works fine after I reset Fault codes

I had for a long time P0171 and P0174 with the car working just fine, so I though it was a small vacuum leak probably and I would find it when the weather would get good.

The last few days it started with some random misfires. Some times it is cylinders 1,2,3. The other time it was only cyl.6 etc. Most of the time it works fine except of a couple times that it gets crazy. Today while I was on the highway it went crazy and it was rattling, shaking, no power... I immediatelly put my BT OBDII scanner on and reset the codes on the way.

At the time I reset the codes it starting driving like a normal car again.

Since it gets ok after resetting the codes, does this mean it is a vacuum leak or something else?
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Old 04-26-2016, 05:33 AM   #2
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Join Date: Jul 2008
Location: USA
Posts: 3,866
My Ride: 2001 330Ci
You have vacuum leaks that are letting an increasing amount of unmetered air into the engine. Fix the leaks.
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Old 04-26-2016, 05:40 AM   #3
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Join Date: Nov 2009
Location: Fairfax, VA USA
Posts: 18,183
My Ride: 330CiC, M5, X5
Your car is broken, you need to fix it. You have a 10+ year old E46 (your car is 16-17 years old), it needs constant care and feeding if you do not choose to perform a major amount of PM. All the plastic and rubber under the hood that holds vacuum needs to be replaced by now. Most of the plastic and rubber parts are due for the 2nd replacement at year 16-17!!

All your answers are listed in this thread - http://forum.e46fanatics.com/showthread.php?p=16727145
Solve your misfires, lean codes, rough idle - http://forum.e46fanatics.com/showthread.php?t=897616

Fuel pump failures - http://forum.e46fanatics.com/showthread.php?t=929501

Temp Info - http://forum.e46fanatics.com/showthread.php?t=964491

Hidden OBC Menu - Check Voltage, Temp, Fuel Level - http://forum.e46fanatics.com/showthread.php?t=239619

E46/E39 GM5 Door Lock Info - www.bmwgm5.com

Lower hose temp switch O-ring - BMW #13621743299

Last edited by jfoj; 04-26-2016 at 05:41 AM.
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Old 04-26-2016, 06:30 PM   #4
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Join Date: Aug 2015
Location: London
Posts: 67
My Ride: '00 e46 330ci
I am trying to narrow down where my vacuum leak comes from. I disconnected my MAF and then shot some WD-40 on the DISA and on the lower intake boot...The rpms did not seem to change.

I think that my problem is the CCV, I'm loosing more oil than I should, I get the lean mixture codes etc and have some smoke from the exhaust some times (smoke like the ones in videos with failed CCVs but not that much).

Should the engine have vacuum from the oil cap during normal operation? If I open my oil cap while the engine is running I don't feel any vacuum at all, is that correct? I saw a video with a guy being happy he had vacuum after installing a catch can.

If it is my CCV I am thinking of installing a catch can rather than replacing the CCV. Does anyone have any photos of how/where to cut and connect the tube that is under the engine plastic cap? I can see in photos and videos clearly then one from the front of the engine, but the other one is not visible anywhere...
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