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2001 325ci MT 250k
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Discussion Starter · #1 ·
Vehicle: 2001 BMW 325ci Manual 250k miles
After having a rough idle and getting lean bank codes to be exact: Fuel Trim bank 1 Control limit, Fuel Trim bank 2 Control limit, Misfire on all cylinders and Fuel Trim Bank 1 & 2, Permissible range exceeded. I replaced my CCV, Intake boot (Lower and Upper) SAP vacuum line, and the non-return valve vacuum lines following the 50's kid video. Once I removed the Intake Manifold (IM), I found out the previous owner removed the vacuum canister and plugged the hole in the IM. Not knowing what to do I continued to replace everything double checking everything was plugged in. After I finished installing everything, the car would start then very rough idle and die within 2-3 secs. The codes I pulled are: System too lean Bank 1 & 2, All Cylinders Misfire with fuel cut off, and Multiple Misfires detected. I'm sure my vacuum lines are in the correct location and plugged in, could this be something like me accidently moving the throttle body flap? I'm worried I messed up. Also the air duct from the front of the engine to the airbox is missing don't know if that would be affecting my prior bad idle.
 

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2002 330ci auto
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I found out the previous owner removed the vacuum canister and plugged the hole in the IM.
The 325 didn't come with the exhaust flap as far as I know so that's missing from factory. Even so, I've done the same and it's perfectly fine. the missing air duct shouldn't be causing any major issues.

I'd go through the no start guide as above. Did you try running with the MAF unplugged?
 

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2001 325ci MT 250k
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Discussion Starter · #7 ·
The 325 didn't come with the exhaust flap as far as I know so that's missing from factory. Even so, I've done the same and it's perfectly fine. the missing air duct shouldn't be causing any major issues.

I'd go through the no start guide as above. Did you try running with the MAF unplugged?
Thanks for the info, I tried with MAF unplugged and it starts and idles around 900rpm but makes popping noises from the engine. What does this mean?
 

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2001 325ci MT 250k
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Discussion Starter · #8 ·
Check your actual CCV, there is a little nipple that is used on M52TU engines (I believe). Sometimes replacement CCVs don't come with this blanked off (mine didn't anyway...) and will cause a big vacuum leak. I used a little rubber blanking cap and it fired right up after that.

EDIT: RealOEM.com - Online BMW Parts Catalog
I'm referring to #6 on this diagram.
I specifically remember transferring the plug from the old CCV to the new one. The 50’s kid also does it in his video which I was following.
 

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2000 E46 323i, 3.0L, 2.8L and 2.0L Z3's
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Will the engine run if you gas it a bit once started?
  • It will not run. Check fuel pressure at the schrader valve on the fuel rail. It should be 50 PSI. You can watch the fuel pressure as you start the engine. If it will not hold 50 PSI then you have a failing fuel pump.
  • It will run. This is indicative of a vacuum leak. Keep searching for it.

Thanks for the info, I tried with MAF unplugged and it starts and idles around 900rpm but makes popping noises from the engine. What does this mean?
With the MAF unplugged, the mixture is very rich. This has allowed the engine to run. Again this is indicative of a vacuum leak as the rich mixture will compensate/mask a vacuum leak. The popping noises will be misfires due to an incorrect mixture.
 

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2001 325ci MT 250k
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Discussion Starter · #10 · (Edited)
Will the engine run if you gas it a bit once started?
  • It will not run. Check fuel pressure at the schrader valve on the fuel rail. It should be 50 PSI. You can watch the fuel pressure as you start the engine. If it will not hold 50 PSI then you have a failing fuel pump.
  • It will run. This is indicative of a vacuum leak. Keep searching for it.


With the MAF unplugged, the mixture is very rich. This has allowed the engine to run. Again this is indicative of a vacuum leak as the rich mixture will compensate/mask a vacuum leak. The popping noises will be misfires due to an incorrect mixture.
Thanks for the information. While the MAF was still connected, the engine would start, rev to 1.5k RPM then shoot down and die. In my attempts to hold the pedal down the car still dies within 2 secs. What equipment would I need to test the fuel pressure? Thanks again!
 

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2005 330xi Auto, 2006 330ci Vert Auto
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Thanks for the information. While the MAF was still connected, the engine would start, rev to 1.5k RPM then shoot down and die. In my attempts to hold the pedal down the car still dies within 2 secs. What equipment would I need to test the fuel pressure? Thanks again!
Lots of options for a fuel pressure test kit. Amazon, for example, has a ton. You can also rent it from places like Autozone for free (you pay for the kit, do your work, then return it for a full refund - see their website). Whatever you end up doing, you need to ensure you have the proper connector/adapter to the BMW schrader valve.

Just one example from Amazon, there are many.

 

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2001 325ci MT 250k
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Discussion Starter · #12 ·
Lots of options for a fuel pressure test kit. Amazon, for example, has a ton. You can also rent it from places like Autozone for free (you pay for the kit, do your work, then return it for a full refund - see their website). Whatever you end up doing, you need to ensure you have the proper connector/adapter to the BMW schrader valve.

Just one example from Amazon, there are many.

Thank You! Gratefully, Amazon will ship that kit tomorrow morning. I also plan on doing a smoke test to find any major leaks. I'll update once I've completed both tests. Thanks!
 

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2001 325ci MT 250k
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Discussion Starter · #13 · (Edited)
Thank You! Gratefully, Amazon will ship that kit tomorrow morning. I also plan on doing a smoke test to find any major leaks. I'll update once I've completed both tests. Thanks!
Fuel Pressure reading about 47 psi with MAF in, with the MAF unplugged it’s about 49 psi.
I recorded the readings:
MAF Unplugged: MAF Unplugged
MAF plugged In: MAF Plugged In fuel pressure
I was sick this entire week couldn’t get the tests done. Darn flu! Waiting on some materials to do a smoke test tomorrow.
 

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2005 330xi Auto, 2006 330ci Vert Auto
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Fuel Pressure reading about 47 psi with MAF in, with the MAF unplugged it’s about 49 psi.
I recorded the readings:
MAF Unplugged: MAF Unplugged
MAF plugged In: MAF Plugged In fuel pressure
I was sick this entire week couldn’t get the tests done. Darn flu! Waiting on some materials to do a smoke test tomorrow.
MAF should have no influence on fuel pressure
 

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2005 330xi Auto, 2006 330ci Vert Auto
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With the MAF plugged in the car dies immediately, so wouldn’t the fuel pressure not have the proper couple of seconds to reach 50 psi? I have no clue just guessing.
MAF is a mass airflow sensor. It’s designed to measure the air mass passing through it and sending a signal to the engine computer (DME) with the measured air mass.
 

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Once I removed the Intake Manifold (IM), I found out the previous owner removed the vacuum canister and plugged the hole in the IM.
What vac canister? Muffler? I don't think 325ci has one.
After I finished installing everything, the car would start then very rough idle and die within 2-3 secs. The codes I pulled are: System too lean Bank 1 & 2, All Cylinders Misfire with fuel cut off, and Multiple Misfires detected. I'm sure my vacuum lines are in the correct location and plugged in, could this be something like me accidently moving the throttle body flap? I'm worried I messed up. Also the air duct from the front of the engine to the airbox is missing don't know if that would be affecting my prior bad idle.
Car died bc mixture was too lean, not because leaking air, but not enough fuel. (Remember the thread about the guy that had the intake manifold exploded but he got the engine running and drove down the mountain -- this tells me engine will run even with a big intake vac leak.)
Could be the injectors are clogged up.
Try to keep it running with starter fluid spray into the air duct with MAF unplugged and air filter removed.
 
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