Whats your rail pressure on cold start?

Recoiletiquette · 06-10-2020, 03:46 PM

I'm having a really rough cold start and my rail pressure on cold start is from 75 to 80 and lpfp reads from 72 to 80. Is that normal to be that low on cold start till it warms up? I guess I should mention it's a 2007 and still has a full bank of index 1 injectors and other bank is 12

WoodE30 · 06-10-2020, 05:13 PM

Those numbers are ok, normal pressures are around 5-6 bar at operation temp. Pull the spark plugs out before a cold start and see if they are fouled from a leaking injector.

Recoiletiquette · 06-10-2020, 06:23 PM

Quote:

Originally Posted by WoodE30

Those numbers are ok, normal pressures are around 5-6 bar at operation temp. Pull the spark plugs out before a cold start and see if they are fouled from a leaking injector.

Ok I'll give that a try I pulled them just now and I found one that had some oil on top of the plug I might have spilt it in there. If it's a leaky injector there will be fuel on the end of the spark plug?

BM3Rrrr · 06-10-2020, 06:28 PM

Quote:

Originally Posted by Recoiletiquette

Ok I'll give that a try I pulled them just now and I found one that had some oil on top of the plug I might have spilt it in there. If it's a leaky injector there will be fuel on the end of the spark plug?

If there is oil on the threads of the spark plug you most likely have a leaking Valve Cover Gasket.
If the plug tip looks wet and smells of fuel then its a leaking injector

Recoiletiquette · 06-10-2020, 07:15 PM

It wasn't on the threads they were dry. It was like literally on the top of the plug what might that be?

Soden82 · 06-10-2020, 07:23 PM

Quote:

Originally Posted by Recoiletiquette

It wasn't on the threads they were dry. It was like literally on the top of the plug what might that be?

That could be from the valve cover leaking into the spark plug tubes and when you pull the plug it gets coated. I had a leaking VC and had oil all over my spark plugs so when I went to test for a leaking injector I couldn't tell if it smelled like fuel or oil due to that

Recoiletiquette · 06-10-2020, 07:36 PM

Quote:

Originally Posted by Soden82

That could be from the valve cover leaking into the spark plug tubes and when you pull the plug it gets coated. I had a leaking VC and had oil all over my spark plugs so when I went to test for a leaking injector I couldn't tell if it smelled like fuel or oil due to that

Ok how did u know it was the valve cover? Just give it time and see if more oil gets in?

BM3Rrrr · 06-10-2020, 11:04 PM

Though the OP said the threads were dry.....In that case if it was leaking it would be on the threads and the tip of the plug.

Did you pull all the plugs? How many were like this?

Recoiletiquette · 06-10-2020, 11:29 PM

Quote:

Originally Posted by BM3Rrrr

Though the OP said the threads were dry.....In that case if it was leaking it would be on the threads and the tip of the plug.

Did you pull all the plugs? How many were like this?

Ya sorry I mean like the threads of the plug are dry I just ment see if more oil leaks into the tube where the coil meets the plug. Cuz as far as i could tell no oil made it past the plug, it was only on the top of the plug and the bottom of the coil pack. And i pulled all of them and it was only one that had oil in it. I know the tip was dry cuz I cleaned the oil out before removing the plug so I could tell if it was also in the cylinder.

Soden82 · 06-11-2020, 11:46 AM

Quote:

Originally Posted by Recoiletiquette

Quote:

Originally Posted by Soden82

That could be from the valve cover leaking into the spark plug tubes and when you pull the plug it gets coated. I had a leaking VC and had oil all over my spark plugs so when I went to test for a leaking injector I couldn't tell if it smelled like fuel or oil due to that

Ok how did u know it was the valve cover? Just give it time and see if more oil gets in?

In my case I examined the valve cover and could visually see the crack. A cracked valve cover will be very obvious as it'll leak a lot of oil in a small amount of time

Recoiletiquette · 06-11-2020, 10:14 PM

Ok well I got the valve cover off today it looks fine and so does the gasket but I got a replacement anyway it was only like $40. And checked my plugs again and they were still dry but there less than a month old and all of them have like really bad black carbon build up on them. That cant be normal right? Is that a rich problem? I do have O2 codes but they are post cat so as far as I know they only test the cat efficiency and dont affect air fuel but also I dont really know.

_N54 · 06-12-2020, 02:01 AM

Well after doing the valve cover, how does the car run now on a cold start?

If it's the same then let it sit overnight and in the morning pull out the spark plugs one ata time again and look at the tips where the electrode is. If the spark plug is wet and it smells like fuel then you have a leaking injector.

Saif2018 · 06-12-2020, 06:28 AM

Quote:

Originally Posted by Recoiletiquette

Ok well I got the valve cover off today it looks fine and so does the gasket but I got a replacement anyway it was only like $40. And checked my plugs again and they were still dry but there less than a month old and all of them have like really bad black carbon build up on them. That cant be normal right? Is that a rich problem? I do have O2 codes but they are post cat so as far as I know they only test the cat efficiency and dont affect air fuel but also I dont really know.

Post cat O2's mistakenly ignored by many owners, they are important.

mweisdorfer · 06-12-2020, 09:44 AM

At idol, 700 something. All index 12.

06-10-2020, 03:46 PM	#1
Recoiletiquette Private 1 Rep 57 Posts Drives: BMW 335I Join Date: May 2020 Location: Utah iTrader: (0)	Whats your rail pressure on cold start? I'm having a really rough cold start and my rail pressure on cold start is from 75 to 80 and lpfp reads from 72 to 80. Is that normal to be that low on cold start till it warms up? I guess I should mention it's a 2007 and still has a full bank of index 1 injectors and other bank is 12 Last edited by Recoiletiquette; 06-10-2020 at 04:12 PM..
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06-10-2020, 05:13 PM	#2
WoodE30 Capt. Maverick 59 Rep 295 Posts Drives: 89 E30 325is, E92 335i N54 Join Date: May 2018 Location: Los Angeles iTrader: (0) Garage List 2013 X5 3.5xdrive [0.00] 1989 325is [0.00] 2008 335I coupe [0.00]	Those numbers are ok, normal pressures are around 5-6 bar at operation temp. Pull the spark plugs out before a cold start and see if they are fouled from a leaking injector.
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06-10-2020, 07:15 PM	#5
Recoiletiquette Private 1 Rep 57 Posts Drives: BMW 335I Join Date: May 2020 Location: Utah iTrader: (0)	It wasn't on the threads they were dry. It was like literally on the top of the plug what might that be?
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06-10-2020, 11:04 PM	#8
BM3Rrrr Davy Jones, Giant Squid 271 Rep 913 Posts Drives: a Pirate Ship Join Date: Jun 2015 Location: The Isle of Tortuga iTrader: (0)	Though the OP said the threads were dry.....In that case if it was leaking it would be on the threads and the tip of the plug. Did you pull all the plugs? How many were like this? __________________ 2010 e90 335i LCI - xHP - Mishimoto - BMS - CPe - Turbosmart - MHD - Eibach - Koni - VMR - LUX
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06-11-2020, 10:14 PM	#11
Recoiletiquette Private 1 Rep 57 Posts Drives: BMW 335I Join Date: May 2020 Location: Utah iTrader: (0)	Ok well I got the valve cover off today it looks fine and so does the gasket but I got a replacement anyway it was only like $40. And checked my plugs again and they were still dry but there less than a month old and all of them have like really bad black carbon build up on them. That cant be normal right? Is that a rich problem? I do have O2 codes but they are post cat so as far as I know they only test the cat efficiency and dont affect air fuel but also I dont really know.
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06-12-2020, 02:01 AM	#12
_N54 Captain 300 Rep 884 Posts Drives: 335d Join Date: Mar 2020 Location: USA iTrader: (0)	Well after doing the valve cover, how does the car run now on a cold start? If it's the same then let it sit overnight and in the morning pull out the spark plugs one ata time again and look at the tips where the electrode is. If the spark plug is wet and it smells like fuel then you have a leaking injector. __________________ 2013 335is - sold 2011 335d
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06-12-2020, 09:44 AM	#14
mweisdorfer Major General 1909 Rep 6,968 Posts Drives: 2007 Black/Black 335i e90 Join Date: Apr 2011 Location: Holly, MI iTrader: (0) Garage List 2007 BMW E90 335i [0.00] 2008 bmw x5 [0.00]	At idol, 700 something. All index 12.
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