Engine Acceleration reduces with a mild hissing sound from engine bay

[80stech]

There is a lot of room for misunderstanding and misinformation in these threads where there is a third party doing the work, that being said I would really look for a different shop at this point. For example, (and I'm not saying that is for sure the problem but) "visually inspecting the exhaust" is meaningless as well as a picture of the fuel pressure gauge. Not being able to post all the codes and descriptions does not help.

[Draculas]

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[Themoog]

What about the Vanos solenoids? I had one stick and it gave similar symptoms but also no codes.

[andrewwynn]

I've had similar symptoms with vanos solenoid (no code), broken oil fill cap (code but unrelated general performance code, and the most common culprit: cam position sensor.

When cps starts to fail it just leads or lags the actual position which opens/closes the valves at the wrong time which of course gives you bad power performance. Since it's sending a signal the computer just believes it.

I will usually confirm my suspicion of a faulty cps by charting it's angle overlap with the other bank same part. It will be subtle. It helps to have a second car to do a comparison ride.

Out of about a dozen cps failure over replaced only one tripped an error code. Usually just bad mid range torque under moderate load and weird stalling but that's on the six cylinder engines. The eights with redundant bankn will stumble but keep running.

[mellow1122]

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[masco]

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[Salty B.]

Been getting this PFEEWF noise underhood when shutting down, like some kind of air pressure reservoir is being purged. Also been having odd deceleration-like moments when it feel like it's decelerating despite my foot not letting up on the pedal. But it's only for a few seconds, then it's all fine. This happened once with the cruise control active at 70mph. Goosed the gas and it went away. It's not crankcase ventilation; there's no PSSSHHT on pulling the oil cap or dipstick.

2001 M54 manual.

[andrewwynn]

What scan solution?

I would use foxwell to monitor the cam angles when you get this condition.

A few different things can cause them to not be the angle they should be and there are six different cam angle values that can be tracked with at least foxwell and surely others.

Cam position sensors original? OEM?

Vanos solenoids ever cleaned?

Oil weight factory spec?

I forgot if the m54 had the cage in the middle of the oil filter but I had one fail on an n52 gave similar symptoms.

How many miles? Both our M54 had the intake CPS fail at 132,000 ± 4000 miles just for reference.

The vanos never gave us any problems on either up to 190/205

I've had vanos solenoid fail on n52 at 125

I've seen oil weight mess with vanos on various engines.

[Salty B.]

Originally Posted by andrewwynn

What scan solution?

I would use foxwell to monitor the cam angles when you get this condition.

A few different things can cause them to not be the angle they should be and there are six different cam angle values that can be tracked with at least foxwell and surely others.

Cam position sensors original? OEM?

Vanos solenoids ever cleaned?

Oil weight factory spec?

I forgot if the m54 had the cage in the middle of the oil filter but I had one fail on an n52 gave similar symptoms.

How many miles? Both our M54 had the intake CPS fail at 132,000 ± 4000 miles just for reference.

The vanos never gave us any problems on either up to 190/205

I've had vanos solenoid fail on n52 at 125

I've seen oil weight mess with vanos on various engines.

No codes present. (I have an Ancel reader which is supposed to read BMW-specific codes).

Prior owner did a vanos rebuild with a kit from ECS, replaced the accelerator pedal (OEM) and DISA valve (Rein) about 20,000mi ago. His spreadsheet also has a "vanos hose" replaced about 40,000mi ago. It has 198,000 on it. No notation of cam pos sensor replacements.

Oil is 5W40 Liquimoly, Mann filter, recently changed. There is a plastic insert that goes into the filter. Now that you mention it, this started after the oil change and filter replacement... all of the prior owner's oil changes used the same oil, every 3,000mi (I have extended that to 5,000mi because $).

[andrewwynn]

Can you read the cam position realtime and can you graph?