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Discussion Starter · #1 ·
2004 325xi- The car has constant pending lean codes for banks 1 and 2, short term fuel trim on idle is a steady 27%, it vibrates decently at idle while in drive/ reverse, but not in park/ neutral. It has a whine that appears at a certain, fairly low cruising throttle position (both with my foot and cruise control), sounds like it's coming from the front/ center area of the car. It occasionally runs rough on cold mornings, like it's running missing a cylinder or two, and dips rpms and dies if you try to give it gas. When I fill it up with more than a bit of gas, getting the car started can be difficult- giving it gas helps keep it from dying, but it'll just stumble and die. This one will happen in phases though- it'll start happening, and then it'll be really bad, and then it'll be fine again. The car also has a weird issue where at 2200-2300 rpm and 2800-3000 rpm it'll make a kind of knocking vibration- always at these rmp ranges, and more commonly in lower gears when accelerating.

I feel like these issues are all connected- I've tried smoking/ pressure testing the intake, and I've yet to find any leaks. One thing I did notice is that if I put pressure/vacuum into the intake and then loosen the oil fill plug, the pressure will rush in/ out instantly, either to fill the vacuum or to escape the manifold. I'm not sure if this indicates that my ccv is operating normally or abnormally, as I've only seen posts about it being clogged, but as all the crankcase vents/ valves I have experience with involve a one way valve, I'm not sure whether or not this is the correct way for this one to operate.

The issues after fueling the car have also led me down the path of possibly having a faulty emissions control solenoid, but I'm not sure how to test this.
 

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If you've exhausted leak testing and come up blank then something in the fuel system. Testing fuel pressure as Bali said is first thing to do and if low a quality brand filter is the first thing to try as it's the cheapest, then it's the pump. Injectors generally don't have much issues but if it's been left standing for long periods then getting them ultrasonically cleaned should get them working properly again.
 

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Discussion Starter · #5 ·
If you've exhausted leak testing and come up blank then something in the fuel system. Testing fuel pressure as Bali said is first thing to do and if low a quality brand filter is the first thing to try as it's the cheapest, then it's the pump. Injectors generally don't have much issues but if it's been left standing for long periods then getting them ultrasonically cleaned should get them working properly again.
I already threw in a filter/pressure regulator, made no difference. I'll start looking at the different fuel system tests soon. I don't think it'd be the injectors, due to misfire codes popping up on seemingly random cylinders.
I already have an obdi2 scanner app that's not obd fusion, I'll see if it'll let me make a proper recording of everything I need. Pretty sure it will. Not sure if the pump has been replaced on the car before as I've never gone and looked at it, but if it's original to the car it'll have 330k km on it.
 

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Discussion Starter · #7 ·
Please describe how you are doing your smoke test, and in particular what smoke test equipment you are using.
I'm smoke testing my car by removing the maf, and hose clamping a strong rubber glove over it. I then put the hose of my fluid transfer pump into the intake through a glove finger. I suck the air out of the system first, and then I pump it back in, this time with the intake of the fluid transfer pump going through a cheap vape with pure glycol to make smoke.
 

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Could this be a bad secondary air pump/valve?

Mine is currently failed, box of parts on the to-do list. Rough idles on startup, occasionally with misfire. Smooths out when warm. A bad EGR valve allows air to escape backward, into the SAP.

There would be corresponding codes for this P0492, P0491, ie. banks one and two, variously described depending on the scan tool.
 

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Discussion Starter · #9 ·
Could this be a bad secondary air pump/valve?

Mine is currently failed, box of parts on the to-do list. Rough idles on startup, occasionally with misfire. Smooths out when warm. A bad EGR valve allows air to escape backward, into the SAP.

There would be corresponding codes for this P0492, P0491, ie. banks one and two, variously described depending on the scan tool.
I took mine off a while ago and blanked it. I have the euro tune on the car so I don't get codes for it. Vacuum line to the valve is disconnected.
 

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2000 E46 323i, 3.0L, 2.8L and 2.0L Z3's
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Have you done any work on the exhaust headers or pre-cat O2 sensors? An exhaust leak before the pre-cat O2's will cause lean codes and no amount of inlet manifold smoke testing will find them.

You can smoke test the exhaust and find them.
 

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I'm smoke testing my car by removing the maf, and hose clamping a strong rubber glove over it. I then put the hose of my fluid transfer pump into the intake through a glove finger. I suck the air out of the system first, and then I pump it back in, this time with the intake of the fluid transfer pump going through a cheap vape with pure glycol to make smoke.
I Know its a popular youtube way of smoke testing, But I don't believe a fluid transfer pump and a cigar - or a vape with glycol - is going to produce enough smoke and enough pressure to find the hard to find vac leaks...like the DISA and others.

I think it might be worth the $$ to get a pro smoke test. I have a pretty good smoke tester...similar to the paint can DIY model used with a compressor, but professionally made.
On occasion, I'll get a really good professional smoke test done by a local indie...solved my lean issue 6 months ago...
 

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Discussion Starter · #12 ·
Might be a soft failing fuel pump. Check fuel pressure at the rail, should be 50 PSI.
Have a read through this post.
Just checked rail pressure- turning the key to pos. 2 immediately makes 50 psi, and approximately 1.5 seconds after that it drops to about 47 psi, and very slowly loses more pressure. After 10 minutes with the key out it had hit 22 psi. I'm pretty sure that this isn't quite right. I replaced the fuel pressure regulator/ fuel filter only a couple months ago as I thought it might be my issue, but maybe I got a bad unit.
 

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Fuel pressure is about right... With the engine running, it likely stays at 50psi..

Recently I had a problem with a fuel regulator in my E39 and it resulted in fuel pressure too high...which led to rich codes.
 

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2005 330xi Auto, 2006 330ci Vert Auto
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OP, your initial post indicated you are getting consistent lean codes. I would focus on getting a good smoke test as the most common reasons for lean codes revolve around vacuum leaks. Like Eff, I'm not a fan of the fluid transfer pump with a cigar or vap. It's very difficult to get consistent pressure and smoke with that setup. Think about how much your time is worth. You can get a really good smoke tester on Amazon for like $80 or build one yourself for $50 (assuming you have an air compressor). Failing that, take it to a shop and pay the 1/2-1 hour of labor to get a good smoke test. Lastly don't forget (as noted by NZ) that an air leak right before the pre-cat O2 sensor cannot be found with a smoke test via the intake. Similarly a vacuum leak at the brake booster also cannot be found with a smoke test via the intake.

Good luck.
 

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Discussion Starter · #15 ·
OP, your initial post indicated you are getting consistent lean codes. I would focus on getting a good smoke test as the most common reasons for lean codes revolve around vacuum leaks. Like Eff, I'm not a fan of the fluid transfer pump with a cigar or vap. It's very difficult to get consistent pressure and smoke with that setup. Think about how much your time is worth. You can get a really good smoke tester on Amazon for like $80 or build one yourself for $50 (assuming you have an air compressor). Failing that, take it to a shop and pay the 1/2-1 hour of labor to get a good smoke test. Lastly don't forget (as noted by NZ) that an air leak right before the pre-cat O2 sensor cannot be found with a smoke test via the intake. Similarly a vacuum leak at the brake booster also cannot be found with a smoke test via the intake.

Good luck.
Thanks, I guess I'll try to find a shop around here that can actually do one. I called a few the other day, and they all said that "hardly anyone around here has the equipment to do it". Probably cheaper to buy one for $90 on amazon or ebay or something, or just make my own- I'm not sure what they use for the heating element, but the rest of it is just a paint can with some fittings, a tube, a universal fitting to connect to the intake, a 1 psi regulator, and some cut-down jumper cables to connect the oil heater to the battery power.
 

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2005 330xi Auto, 2006 330ci Vert Auto
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Thanks, I guess I'll try to find a shop around here that can actually do one. I called a few the other day, and they all said that "hardly anyone around here has the equipment to do it". Probably cheaper to buy one for $90 on amazon or ebay or something, or just make my own- I'm not sure what they use for the heating element, but the rest of it is just a paint can with some fittings, a tube, a universal fitting to connect to the intake, a 1 psi regulator, and some cut-down jumper cables to connect the oil heater to the battery power.
Resistance wire can be used for the heating element. I chose to build my own, but as you already noted, you can buy one for about $80-$90. I enjoyed building my own stuff so even though for the money I spent I could've bought one, I do not regret building one.

 

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I'll try to find a shop around here that can actually do one. I called a few the other day, and they all said that "hardly anyone around here has the equipment to do it".
Any shop that does not have a smoke tester you should stay away from. It’s a standard required rool (among others) for diagnosis.
 

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2000 E46 323i, 3.0L, 2.8L and 2.0L Z3's
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Sounds like you are stuck. Try installing OBD Fusion. Read the PDF file to set it up and run the 3 standard logs. Post links to the CSV files here and we'll have a look.

The reason we like using OBD Fusion is that it gives us lots of helpful engine data without having to ask you 1,000 questions.
 
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