engine knocks

Z22Z · 12-03-2009, 03:02 AM

my engine knocks sometimes while warm and the rpm at idle will drop from around 750 to 500 and then bounce up and down a few times. it isn't noticeable by passengers but kind of annoying. any ideas on what it could be?

enrita · 12-03-2009, 03:37 AM

how do you know is actually knocking ? Sounds like High pressure fuel pump failure. take it to the dealer.

cstmx_ryder · 12-03-2009, 03:48 AM

ya, I thought knock can only be detected or seen through datalogging?

enrita · 12-03-2009, 03:56 AM

Quote:

Originally Posted by cstmx_ryder

ya, I thought knock can only be detected or seen through datalogging?

superman ears maybe

ianthegreat · 12-03-2009, 09:09 AM

Quote:

Originally Posted by enrita

how do you know is actually knocking ? Sounds like High pressure fuel pump failure. take it to the dealer.

+1

The engine will bog way down and it "sounds" like knock, but it's probably just the engine itself rattling from almost stalling.

possible335i2008 · 12-03-2009, 09:27 AM

best term for that are "cold starts" to actually determine knock requires datalogging.

BavarianBullet · 12-03-2009, 09:29 AM

Quote:

Originally Posted by ianthegreat

+1

The engine will bog way down and it "sounds" like knock, but it's probably just the engine itself rattling from almost stalling.

+1.

cn555ic · 12-03-2009, 10:45 AM

Quote:

Originally Posted by possible335i2008

best term for that are "cold starts" to actually determine knock requires datalogging.

Yeah but sometimes datalogging for knock is also flawed!!

cstmx_ryder · 12-03-2009, 03:43 PM

Quote:

Originally Posted by cn555ic

Yeah but sometimes datalogging for knock is also flawed!!

So what's the best way to determine if you're knocking or not? I thought datalogging would come the closest to being accurate........IDK.

enrita · 12-03-2009, 03:45 PM

When you are about to knock you feel it since the car is pulling timings. so Datalogging will show a good picture in what is going on .

cstmx_ryder · 12-03-2009, 04:03 PM

How would the car feel? Kind of choking or slight stuttering....or??

TIA

Easternedge · 12-03-2009, 04:41 PM

May be the lifters knocking...

enrita · 12-03-2009, 04:42 PM

basically a big hesitation in revving up, sudden loss of power.

Z22Z · 12-03-2009, 08:14 PM

my bad on the terminology. it feels like the car shudders and it only happens when the car is at normal operating temps. i also dont have the long cranks that come with the HPFP.

12-03-2009, 03:02 AM	#1
Z22Z Lieutenant 35 Rep 536 Posts Drives: WRX Join Date: Dec 2008 Location: Glendale, CA iTrader: (0)	engine knocks my engine knocks sometimes while warm and the rpm at idle will drop from around 750 to 500 and then bounce up and down a few times. it isn't noticeable by passengers but kind of annoying. any ideas on what it could be?
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12-03-2009, 03:37 AM	#2
enrita Major General 163 Rep 7,377 Posts Drives: 335i - Big turbos Join Date: Sep 2008 Location: Italian in Sweden iTrader: (0)	how do you know is actually knocking ? Sounds like High pressure fuel pump failure. take it to the dealer. __________________ 07 335i AT - MOTIV 750 - MHD E85 BMS flash - BMS PI - JB4G5 - Okada Coils - NGK 5992 Plugs - Helix IC - Snow Stg. 3 - Stett CP - Custom midpipes with 100 HJS Cats - Bastuck Quad - PSS10 - QUAIFE LSD - BMS OCC - Forge DVs - AR OC - ALCON BBK - M3 Chassi - Dinan CP - Velocity M rear Toe arms - Advan RZ-DF - LUX H8 - Level 10 AT upgrade
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12-03-2009, 03:48 AM	#3
cstmx_ryder Colonel 178 Rep 2,875 Posts Drives: A metal box with a roundel Join Date: Jul 2007 Location: Portland, OR iTrader: (2)	ya, I thought knock can only be detected or seen through datalogging? __________________ '08 AW E90 335i PROcede V5 \| BMS DCI \| RR DPs \| ETS FMIC \| FORGE DVs \| Stett CP \| Vanguard \| PSS10
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12-03-2009, 09:27 AM	#6
possible335i2008 Major 186 Rep 1,222 Posts Drives: 335i Join Date: Mar 2008 Location: united states iTrader: (10)	best term for that are "cold starts" to actually determine knock requires datalogging.
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12-03-2009, 03:45 PM	#10
enrita Major General 163 Rep 7,377 Posts Drives: 335i - Big turbos Join Date: Sep 2008 Location: Italian in Sweden iTrader: (0)	When you are about to knock you feel it since the car is pulling timings. so Datalogging will show a good picture in what is going on . __________________ 07 335i AT - MOTIV 750 - MHD E85 BMS flash - BMS PI - JB4G5 - Okada Coils - NGK 5992 Plugs - Helix IC - Snow Stg. 3 - Stett CP - Custom midpipes with 100 HJS Cats - Bastuck Quad - PSS10 - QUAIFE LSD - BMS OCC - Forge DVs - AR OC - ALCON BBK - M3 Chassi - Dinan CP - Velocity M rear Toe arms - Advan RZ-DF - LUX H8 - Level 10 AT upgrade
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12-03-2009, 04:03 PM	#11
cstmx_ryder Colonel 178 Rep 2,875 Posts Drives: A metal box with a roundel Join Date: Jul 2007 Location: Portland, OR iTrader: (2)	How would the car feel? Kind of choking or slight stuttering....or?? TIA __________________ '08 AW E90 335i PROcede V5 \| BMS DCI \| RR DPs \| ETS FMIC \| FORGE DVs \| Stett CP \| Vanguard \| PSS10
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12-03-2009, 04:41 PM	#12
Easternedge Major 132 Rep 1,243 Posts Drives: 2012 Mini Coupe S JCW Join Date: Oct 2008 Location: Aventura, FL iTrader: (4) Garage List 2011 BMW 335is [0.00]	May be the lifters knocking... __________________ Back again after 10 yrs! Daily: 2012 Mini coupe S JCW Baby: 2007 BMW M6 Vert Wifey's: 2006 BMW 650I Family: 2007 Chevy Suburban LTZ
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12-03-2009, 04:42 PM	#13
enrita Major General 163 Rep 7,377 Posts Drives: 335i - Big turbos Join Date: Sep 2008 Location: Italian in Sweden iTrader: (0)	basically a big hesitation in revving up, sudden loss of power. __________________ 07 335i AT - MOTIV 750 - MHD E85 BMS flash - BMS PI - JB4G5 - Okada Coils - NGK 5992 Plugs - Helix IC - Snow Stg. 3 - Stett CP - Custom midpipes with 100 HJS Cats - Bastuck Quad - PSS10 - QUAIFE LSD - BMS OCC - Forge DVs - AR OC - ALCON BBK - M3 Chassi - Dinan CP - Velocity M rear Toe arms - Advan RZ-DF - LUX H8 - Level 10 AT upgrade
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12-03-2009, 08:14 PM	#14
Z22Z Lieutenant 35 Rep 536 Posts Drives: WRX Join Date: Dec 2008 Location: Glendale, CA iTrader: (0)	my bad on the terminology. it feels like the car shudders and it only happens when the car is at normal operating temps. i also dont have the long cranks that come with the HPFP.
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