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BMW 330i E46 2003 - Misfire on #3 cylinder, code P0303 - Fixed #

Posted by Paul Eady on September 14, 2012, 8:53 am

Year of Manufacture *: 2003
Engine Size and Code *: 2979cc 24V M54B30
( Optional ) Scanner Used: Verus
( Optional) Fault Codes: Bmw 240 p0303

Code P0303 stored, new coil fitted to cylinder 3 ( not by us )
We rescanned it & code 240 is present again.
The strange thing is that the engine is clearly missing but only from the days first start,if you then turn the engine off & back on again the missfire is gone & after clearing no codes recorded untill next morning.
I have started the engine from cold & run to normal temp, missfire still present, until turned off & back on, or run the engine from cold for 30 secs, off & back on & all is fine.

Re: BMW 330i E46 Missfire number 3

Posted by aidan birley <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2879' width='330' height='300' border=0 style='border:none;'> on September 14, 2012, 1:19 pm, in reply to "BMW 330i E46 Missfire number 3"
Aidan Birley

Hi

>>>>The strange thing is that the engine is clearly missing but only from the days first start,if you then turn the engine off & back on again the missfire is gone & after clearing no codes recorded untill next morning. <<<<

Is it shutting down the injector due to the misfire detected ?

Possible mechanical issue e.g head gasket ( coolant in cylinder ) or valve / lifter fault

cheers Aidan

Re: BMW 330i E46 Missfire number 3

Posted by Paul Eady <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1815' width='330' height='300' border=0 style='border:none;'> on September 14, 2012, 2:03 pm, in reply to "Re: BMW 330i E46 Missfire number 3"

Thanks for the reply.
from that i think i will try swopping an injector first.
I don't realy think its a head gasket at this stage because it clears on a restart weather its 30 secs or 10 mins running.
Will also check & swop a coil just in case its a flea bay special.

Re: BMW 330i E46 Missfire number 3

Posted by Mark Carter <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1428' width='330' height='300' border=0 style='border:none;'> on September 14, 2012, 6:59 pm, in reply to "Re: BMW 330i E46 Missfire number 3"
Mark Carter

On the face of it I'm more with valves/lifters.

If an injector or a coil is playing up a reset will make no difference, but it will clear a misfire code as Aidan has said.

Mark

Modern cars, Its all wizardry and witchcraft

Re: BMW 330i E46 Missfire number 3

Posted by Bryan Smith <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5330' width='330' height='300' border=0 style='border:none;'> on September 14, 2012, 7:47 pm, in reply to "Re: BMW 330i E46 Missfire number 3"
Bryan Smith

I'm opting for head gasket. Coolant leaking overnight and then clearing in the first few seconds after start up????? But then again, even money on lifters????

Regards,
Bryan.

Re: BMW 330i E46 Missfire number 3

Posted by Mark Carter <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1428' width='330' height='300' border=0 style='border:none;'> on September 14, 2012, 10:25 pm, in reply to "Re: BMW 330i E46 Missfire number 3"
Mark Carter

Question: Who is going to hold the pot?

Modern cars, Its all wizardry and witchcraft

Re: BMW 330i E46 Missfire number 3

Posted by Tony Attwood <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=ukat3025' width='330' height='300' border=0 style='border:none;'> on September 14, 2012, 10:57 pm, in reply to "Re: BMW 330i E46 Missfire number 3"
Tony Attwood

Hi,
Any coolant loss at all Paul, or discolouration of coolant?

A sniff test followed by compression test and cylinder leakage test, before and after engine running, may help to prove / disprove all above theories. Albeit time consuming!!

Tony

Re: BMW 330i E46 Missfire number 3

Posted by Paul Eady <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1815' width='330' height='300' border=0 style='border:none;'> on September 15, 2012, 10:29 am, in reply to "Re: BMW 330i E46 Missfire number 3"
Paul Eady

No coolant loss at all & no pressure remaining overnight.
Will sleep on it over the weekend & perhaps it will fix its self,with any luck.If not who wants it??

Re: BMW 330i E46 Missfire number 3

Posted by Sean Murphy <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1788' width='330' height='300' border=0 style='border:none;'> on September 26, 2012, 8:53 pm, in reply to "Re: BMW 330i E46 Missfire number 3"

I've had this exact symptom - turned out to be a sticky hydraulic valve lifter. Sticks first thing in the morning but after 15 seconds, after the pressure overcame the sticking, all was well for the rest of the day untill the next morning when it returned. Renewed all the lifters on that cylinder (#4 in my case)and problem cured.

Fixed #

Posted by Paul Eady on January 26, 2013, 2:52 pm, in reply to "BMW 330i E46 2003 - Misfire on #3 cylinder, code P0303 #"
Message modified by board administrator January 27, 2013, 1:18 pm

FIXED

Turned out to be the E.C.U, poor internal pin connection

Thanks

Paul

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