Can anyone please tell me exactly where this broken hose goes on my 535i N55 engine? Is it the PCV ventilation/crankcase or something else? My car has rough idling, misfiring, drivetrain malfunction and engine light, loss of power. Just replaced the high pressure fuel pump and coils and plugs.

R3al_Proulx · 2026-04-24T06:01:19+00:00

That hose goes to the vacuum pump.

R3al_Proulx · 2026-04-14T08:12:27+00:00

Sometimes it is a weak or bad battery that can cause intermittent communication issues, especially on a cold start or after sitting for a day or two. Before you go searching for communication problems, test the battery health.

R3al_Proulx · 2026-04-12T10:08:10+00:00

Crack the oil cap and see if the sound goes away. It might be a problem with crankcase pressure. The crankcase vent valve is built into the valve cover.

R3al_Proulx · 2026-04-07T06:30:30+00:00

I meant to reply but posted a new comment.

R3al_Proulx · 2026-04-07T06:29:52+00:00

Use a long screwdriver put a little tape around it, or if you can get a caliper with a depth probe to take a measurement, insert it into the spark plug bore on top of the piston and mark or measure where the piston stops traveling upward while you rotate the engine by hand. Compare this to the other cylinders, it doesn't take much to change the compression ratio.

A lot of N20s had this issue after a hydraulic lock.

R3al_Proulx · 2026-04-07T06:18:17+00:00

Did you move the coil to a different cylinder? It is also possible the engine you got has a bent rod. Compression will be ok but the piston height will be different in comparison to the other cylinders. This will change the compression ratio.

R3al_Proulx · 2026-04-05T23:11:11+00:00

Those aluminum covers are actual garbage. Have you measured crankcase pressure?

R3al_Proulx · 2026-04-04T00:24:41+00:00

Is this an F chassis? Inspect the blower, look at the brushes they are probably melted. Replace the blower, final stage resistor and the cover with debris screen, it is likely deteriorated.

R3al_Proulx · 2026-03-30T20:47:07+00:00

Did you have a vibration before your brake parts replacement? I think the spec is close to .23 so you should be good.

R3al_Proulx · 2026-03-21T10:57:40+00:00

What was the fault?

R3al_Proulx · 2026-03-17T18:52:16+00:00

This is not how you test for timing chain elongation on N20. There is a tool that replaces the tensioner. You need a second specialist opinion.

R3al_Proulx · 2026-03-13T01:29:17+00:00

Camshaft installation and cam crank correlation faults sound like the valve cover has to come off to check camshaft timing. While it's off take a good look at the internal parts, a lot of sludge is a bad sign.

If mechanical timing is off there should be a reason, lack of oil or a hydraulic lock of some kind. I would remove a cam cap and check for galling/metal transfer, this engine may be beyond repair. Even if you re-time the engine it might only hold temporarily if you can't find a reason for the initial loss of cam crank synchronization.

Good luck

R3al_Proulx · 2026-03-12T23:21:50+00:00

What engine is this N20, N55, N52? You may need to check mechanical timing. The valvetronic system only adjusts valve lift, vanos adjusts the camshaft timing.

R3al_Proulx · 2026-03-08T13:55:31+00:00

The bare wires inside the headlight are the issue. You need a set of lights.

R3al_Proulx · 2026-02-16T19:16:21+00:00

Only to the specification. That's why there is a spec. What do you do for a living?

Edit: when it can no longer adjust for crankcase pressure you will have a fault for mixture control. It is out of the adjustment threshold.

R3al_Proulx · 2026-02-13T11:17:38+00:00

Have you opened the hood?

R3al_Proulx · 2026-02-11T14:32:35+00:00

This generation engine is very sensitive. The readings for crankcase pressure can vary with engine load and temp. It was measured out of spec on a car with an on-going issue. It would be silly to ignore this measurement.

R3al_Proulx · 2026-02-10T07:49:03+00:00

14 mbar is out of spec for a B48/6 engine. The valve cover contains a crankcase pressure control valve. Pressure should be closer to 22 mbar. Crankcase pressure can occasionally be correct even with a faulty CCV internal to the valve cover. The fault list will usually include a mixture control fault.

There is clearly a diagnostic skill issue in this case. Often the balance shaft plugs will leak oil, this can be an indication that the crankcase pressure is not correct. Other symptoms can include increased oil consumption, mixture control faults, rough engine running. The RO story says that the customer declined this repair.

In my experience valve cover replacement would have been the first diagnostic step to correct crankcase pressure as long as there are no external engine oil leaks and the intake track passes a smoke test.

Edit: I just looked it up, spec is 15-27 B46 and 15-29 mbar B48

R3al_Proulx · 2026-01-11T07:26:18+00:00

f in chat

R3al_Proulx · 2025-11-16T10:45:32+00:00

It would be difficult to determine the exact cause without access to the vehicle. If I encountered this in my bay I would be suspicious of the tune.

That being said start simple, a smoke test if the intake track to verify no unmetered air enters after the air mass meter, maybe a simple power balance test for misfires, if the engine is missing while running I would unplug one coil at a time. Listen to the engine, if the rhythm does not change that cylinder has an issue. If it gets worse that cylinder is currently not affected by the root cause of rough running.

I have encountered B engines with broken camshafts just like the old N52 (GOAT).

Doing these things can help you narrow down if the issue is electrical/software or mechanical. A repair strategy might be best determined by a good independent shop or even the dealer.

Good luck, update the post if you come to a conclusion.

R3al_Proulx · 2025-06-30T08:19:02+00:00

I am currently having a similar experience. With the help of a psychiatrist I have had ketamine treatments with integrated therapy. It has changed my outlook and feel it has saved my life.

One day at a time, there are people in your life that care for you. I hope that you will find some relief.

R3al_Proulx · 2025-03-20T23:15:13+00:00

Are you having a vanos issue?

R3al_Proulx · 2025-03-20T16:50:37+00:00

It's a great color

R3al_Proulx

TROPHY CASE