Strange Boost & Vacuum readings

335ibob · 02-18-2009, 02:42 PM

I'm puzzled & can't figure out whats going on with my car. I have the following mods JB3, AA BOV, AFE Dry intake & boost gauge. Also my car is an automatic if that makes a difference. Weather has been 45-60F during all observations.

The setup I was running: JB3, AA BOV & AFE intake. My boost guage shows the car was running about 14PSI & 18-20 In-Hg at idle. I had to take it in for service so I removed all the mods.

Got the car back and hooked up the boost gauge and was only seeing 6PSI & 10In-Hg at idle.(Car is completely stock minus Boost gauge)

Added the JB3 I was shocked to see I'm getting about 11PSI & 10-12 In-Hg at idle.

Switched out the stock DV and stock intake so I'm back to my configuration before taking my car in for service. running the JB3, AA BOV, AFE intake & boost gauge. I'm still getting 11PSI & 10-12 In-Hg at idle.

Anyone have any clues as to what may be causing this? vacuum line leak? ecu update? charge pipe? I am reusing all the same hardware vacuum T's and lines as I had in the car before. I even put zip ties on the vacuum line meeting the T for the boos gauge and it still seems off.

GGreek5 · 02-18-2009, 02:55 PM

Quote:

Originally Posted by 335ibob

I'm puzzled & can't figure out whats going on with my car. I have the following mods JB3, AA BOV, AFE Dry intake & boost gauge. Also my car is an automatic if that makes a difference. Weather has been 45-60F during all observations.

The setup I was running: JB3, AA BOV & AFE intake. My boost guage shows the car was running about 14PSI & 18-20 In-Hg at idle. I had to take it in for service so I removed all the mods.

Got the car back and hooked up the boost gauge and was only seeing 6PSI & 10In-Hg at idle.(Car is completely stock minus Boost gauge)

Added the JB3 I was shocked to see I'm getting about 11PSI & 10-12 In-Hg at idle.

Switched out the stock DV and stock intake so I'm back to my configuration before taking my car in for service. running the JB3, AA BOV, AFE intake & boost gauge. I'm still getting 11PSI & 10-12 In-Hg at idle.

Anyone have any clues as to what may be causing this? vacuum line leak? ecu update? charge pipe? I am reusing all the same hardware vacuum T's and lines as I had in the car before. I even put zip ties on the vacuum line meeting the T for the boos gauge and it still seems off.

Recalibrate the boost gauge??

scalbert · 02-18-2009, 03:01 PM

Sounds like the line got pulled on one end, is split at the connection or has a hole.

ThorsHammer · 02-18-2009, 03:06 PM

Quote:

Originally Posted by scalbert

Sounds like the line got pulled on one end, is split at the connection or has a hole.

+1

Check those vacuum lines and T fitting on the passenger's side of the engine. I had a split/disconnect there and had the same symptoms.

335ibob · 02-18-2009, 03:32 PM

Quote:

Originally Posted by ThorsHammer

+1

Check those vacuum lines and T fitting on the passenger's side of the engine. I had a split/disconnect there and had the same symptoms.

Can you explain a little more where and what to look for?

scalbert · 02-18-2009, 03:33 PM

Quote:

Originally Posted by 335ibob

Can you explain a little more where and what to look for?

Follow the vacuum line for the boost gauge first.

335ibob · 02-18-2009, 03:39 PM

Are you talking about the vacuum line from the manifold leaking or being split?

scalbert · 02-18-2009, 03:40 PM

Correct, the one from manifold (possibly near the Y at the diverter valves) to the actual gauge. The end on one side could be loose, split or a hole somewhere along.

335ibob · 02-18-2009, 03:53 PM

Quote:

Originally Posted by scalbert

Correct, the one from manifold (possibly near the Y at the diverter valves) to the actual gauge. The end on one side could be loose, split or a hole somewhere along.

Alright I'll re-check the vacuum line and connections. When you had your leak did your boost gauge fluctuate when boosting or pulling vacuum? Cause my numbers are pretty solid for instance when at WOT its a solid 11PSI and when off the gas its usually drops to 10In-Hg and stays there.

scalbert · 02-18-2009, 03:56 PM

Quote:

Originally Posted by 335ibob

Alright I'll re-check the vacuum line and connections. When you had your leak did your boost gauge fluctuate when boosting or pulling vacuum? Cause my numbers are pretty solid for instance when at WOT its a solid 11PSI and when off the gas its usually drops to 10In-Hg and stays there.

It wasn't me that had the leak but I know what a leak would do and it sounds like what you are seeing. That is provided you are watching vacuum only after the engine is fully warm.

335ibob · 02-18-2009, 04:01 PM

yea all these readings are after its warm 230F on the oil temp. thanks for the help i'll check it out when i get home.

1clean335i · 02-18-2009, 07:27 PM

try hooking up another boost gauge

02-18-2009, 02:42 PM	#1
335ibob Enlisted Member 1 Rep 32 Posts Drives: 335i Join Date: Oct 2007 Location: SoCal iTrader: (0)	Strange Boost & Vacuum readings I'm puzzled & can't figure out whats going on with my car. I have the following mods JB3, AA BOV, AFE Dry intake & boost gauge. Also my car is an automatic if that makes a difference. Weather has been 45-60F during all observations. The setup I was running: JB3, AA BOV & AFE intake. My boost guage shows the car was running about 14PSI & 18-20 In-Hg at idle. I had to take it in for service so I removed all the mods. Got the car back and hooked up the boost gauge and was only seeing 6PSI & 10In-Hg at idle.(Car is completely stock minus Boost gauge) Added the JB3 I was shocked to see I'm getting about 11PSI & 10-12 In-Hg at idle. Switched out the stock DV and stock intake so I'm back to my configuration before taking my car in for service. running the JB3, AA BOV, AFE intake & boost gauge. I'm still getting 11PSI & 10-12 In-Hg at idle. Anyone have any clues as to what may be causing this? vacuum line leak? ecu update? charge pipe? I am reusing all the same hardware vacuum T's and lines as I had in the car before. I even put zip ties on the vacuum line meeting the T for the boos gauge and it still seems off.
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02-18-2009, 03:01 PM	#3
scalbert Major General 161 Rep 5,776 Posts Drives: '13 S4, '15 Q7 Join Date: Feb 2007 Location: Woodstock, GA iTrader: (8)	Sounds like the line got pulled on one end, is split at the connection or has a hole.
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02-18-2009, 03:39 PM	#7
335ibob Enlisted Member 1 Rep 32 Posts Drives: 335i Join Date: Oct 2007 Location: SoCal iTrader: (0)	Are you talking about the vacuum line from the manifold leaking or being split?
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02-18-2009, 03:40 PM	#8
scalbert Major General 161 Rep 5,776 Posts Drives: '13 S4, '15 Q7 Join Date: Feb 2007 Location: Woodstock, GA iTrader: (8)	Correct, the one from manifold (possibly near the Y at the diverter valves) to the actual gauge. The end on one side could be loose, split or a hole somewhere along.
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02-18-2009, 04:01 PM	#11
335ibob Enlisted Member 1 Rep 32 Posts Drives: 335i Join Date: Oct 2007 Location: SoCal iTrader: (0)	yea all these readings are after its warm 230F on the oil temp. thanks for the help i'll check it out when i get home.
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02-18-2009, 07:27 PM	#12
1clean335i Perf BMW mag issue 147, 159 435 Rep 6,799 Posts Drives: Project Estoril Join Date: Feb 2007 Location: Miami, FL iTrader: (31) Garage List 2013 335i M-sport [0.00] 2011 X5 xdrive35i M ... [0.00] 2009 335i M-sport [0.00] 07' 335i Sedan [0.00]	try hooking up another boost gauge __________________ '13 Estoril Blue 335i M-sport *Don't PM me!* Message me here- http://www.facebook.com/ProjectEstoril
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