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Was driving and heard a pop noise and now hearing a whistling noise when accelerating

Tiny
SNIPER7799_9977
  • MEMBER
  • 2007 BMW 335
  • 3.0L
  • 6 CYL
  • TURBO
  • 2WD
  • AUTOMATIC
  • 150,000 MILES
Just had brand new hybrid turbos installed less than 100 miles ago.
Loose inlet pipe or bad turbos?

https://www.youtube.com/watch?v=7gQZ0t02R2Q

Thanks
Sunday, April 4th, 2021 AT 6:26 PM

13 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 POSTS
Hi,

I hear the turbos spooling and see the RPM's jump. Is there a different noise you are referring to? The way the RPM's are jumping seems like the transmission is slipping.

Let me know.

Joe
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Monday, April 5th, 2021 AT 6:48 PM
Tiny
SNIPER7799_9977
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Are they supposed to sound that loud if a inlet pipe came loose? Also have no power/boost.

As for the transmission I just had stage 3 remap installed so it wants to stay in higher gear so I was down shifting a lot in the video so you can hear the noise more.

Thanks
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Monday, April 5th, 2021 AT 11:12 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Hi,

If you have no boost, check the charge air tube, It runs up to the air box. I attached the best pic I have below. They are known to break (crack) which affects the turbo. Also, I don't know what modifications were done, but is the check engine light staying on while the engine is running?

Let me know.

Joe
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Tuesday, April 6th, 2021 AT 5:55 PM
Tiny
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The codes for the check engine light are:

P0171 - System to lean, Bank 1
P0174 - System to lean, Bank 2

I’ve had all those parts installed/replaced when I got the turbos installed:

High pressure fuel pump
O2 sensors
RB PCV valve
Radiator
Upgraded intercooler
Upgraded charge pipe
Upgraded inlet pipes
Boost solenoids
Diverter valves
Thermostat
Vanos solenoids

Could a bad alternator cause the engine to run lean? I’ve noticed if I turn the ignition on the battery drains within few minutes. Battery is brand new.

Thanks
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Tuesday, April 6th, 2021 AT 8:12 PM
Tiny
JACOBANDNICKOLAS
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Hi,

It isn't an electrical issue. If it is running lean, either you have a weak pump, an engine vacuum leak, or even an exhaust leak before the catalytic converters.

Did you check the charge air tube? Also, I need you to check for vacuum leaks. Here is a link that shows how. Something is allowing too much air to get into the engine.

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Start with that. Also, let me know if the fuel pressure has been checked. I noted you replaced the pump, but anything is possible.

Again, the idea you have no or little boost leads me to believe the problem may be related to the charge air tube. That would create a vacuum leak as well.

Take care and let me know what you find,

Joe
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Wednesday, April 7th, 2021 AT 7:02 PM
Tiny
SNIPER7799_9977
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All vacuum lines seem to be fine and the charge air tube is secure with no cracks, I’ve also noticed if I press down the accelerator and keep the RPMs at around 1,500 it isn’t stable it drops down to around 1,000 RPMs then back up and continues to do that.

I was getting misfire on cylinder 5 and pulled the injector and found this, I’ve since replaced that injector but still running lean, maybe all the injectors need replaced?

I forgot to mention I’ve downpipes installed and have had the rear catalytic converters removed.

Thanks
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Wednesday, April 7th, 2021 AT 7:56 PM
Tiny
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Hi,

The idea that you removed the converters may have something to do with the lean mixture. What was done with the downstream oxygen sensors?

Joe
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Thursday, April 8th, 2021 AT 6:17 PM
Tiny
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They are unplugged and coded out, I've been running it without them for the last year with no problems or codes.
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Thursday, April 8th, 2021 AT 6:33 PM
Tiny
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Okay. If you have no vacuum leaks, have you checked the fuel pressure? Also, and I may have already asked this, but do you know the short-term fuel trims?

Joe
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Thursday, April 8th, 2021 AT 7:07 PM
Tiny
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The fuel pressure seems to drop under 600 when driving and hits around 2700 PSI under load.
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Thursday, April 8th, 2021 AT 7:11 PM
Tiny
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Normal stft should between +10% and --10%. If I'm reading your scanner correctly, bank 2 is running near 35% and then to --35%. Something is causing the computer to add a ton of fuel to that bank. Are you certain there isn't an vacuum leak? Do you still have the upstream o2 sensors? If you do, is there any chance of an exhaust leak before the sensor?

Joe
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Thursday, April 8th, 2021 AT 7:24 PM
Tiny
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Yes, the upstream o2 sensors are still in. I will jack the car up tomorrow and check over the exhaust for any leaks.

If the rear inlet pipe came loose from the turbo (like in the photo) would that cause all the issues i'm having with no boost and the loud turbo noise?

Thanks
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Thursday, April 8th, 2021 AT 7:33 PM
Tiny
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Hi,

Yes, that will cause an issue. As far as the exhaust leak, check around the exhaust manifold. If there is a leak pre-cat, unmetered air can get into the system and the upstream sensor can think it's a lean mixture. As a result, the computer tries to compensate by adding fuel. Hence the high STFT readings.

Let me know.

Joe
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Thursday, April 8th, 2021 AT 8:58 PM

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