Diagnose brake problem. Booster? Jet pump?

[GAH111]

Would be nice if it was something as simple as a MAF. Any feed back on the brake booster. Do you suspect it has also gone bad? Since there are no cats shouldn't the 02 sensors read the same?

Thanks,
GH

[sapote]

Would be nice if it was something as simple as a MAF. Any feed back on the brake booster. Do you suspect it has also gone bad? Since there are no cats shouldn't the 02 sensors read the same?

Thanks,
GH

With zero data on O2 sensors, and a bad MAF (or its connection/wiring), I can't confirm the booster is leaking.

[GAH111]

I'll get another MAF but will this solve my brake booster problem.

G.H.

[sapote]

I'll get another MAF but will this solve my brake booster problem.

G.H.

Fixing a bad MAF has no effect on brake booster. If it does then BMW would have many lawsuits.

[GAH111]

So to clarify, replace then MAF then rediagnose the brake problem?

[sapote]

So to clarify, replace then MAF then rediagnose the brake problem?

Yes, with better log file included the suggested parameters.

[GAH111]

I replaced the MAF yesterday and the car is still running extremely rich with a rough idle. the latest datazap log is attached. Please let me know your thoughts as soon as possible, I will need to leave this location later this week

https://datazap.me/u/2004m3/logs/cmnxmyurm000tjj0637qgn70w?channels=6&sizes=100&sc=1-6-7-9-12-13-14

[GAH111]

One last thought. I started to remove the brake booster, I got as far as unbolting the master cylinder before I ran the logs. I then re-attahced it and ran the logs. Is there a way that I caused a vacuum leak when bolting it back to the booster.

[sapote]

One last thought. I started to remove the brake booster, I got as far as unbolting the master cylinder before I ran the logs. I then re-attahced it and ran the logs. Is there a way that I caused a vacuum leak when bolting it back to the booster.

with master removed, a big 1" hole leaking air into the intake via booster, but the MAF is still too high instead of too low.

I don't see the log clearly labeled pre and post master installed. Remember I cant read your mind.

[sapote]

. Is there a way that I caused a vacuum leak when bolting it back to the booster.

If the master base rubber o-ring didn't fall off and in good shape, then doing this should not cause leaking air into the booster. However, the two 13mm stud (for holding the master) can leak and this depends on how the booster to master interface surface flatness (I don't like this design and it's safe to add some RTV around the base of these studs to ensure a tight air seal.
It seems the new MAF makes no difference compared to the old one, that the MAF reading is too high at idle. This issue might be related to the wiring or the DME itself. High MAF reading leads to rich mixture.

[GAH111]

No need to read my mind, just the text. As stated I replaced the master cylinder then ran the logs. It has been suggested that because the 02 sensors are showing .01v I should check the fuses to he heater circuits and ground circuits from the ECU. Concur?

[sapote]

No need to read my mind, just the text. As stated I replaced the master cylinder then ran the logs. It has been suggested that because the 02 sensors are showing .01v I should check the fuses to he heater circuits and ground circuits from the ECU. Concur?

Your text is clear but my mind was foggy
You should delete the last 4 PIDs (parameters) and Vehicle Speed so it looks less cluster. I still don't see the O2 sensors in the log, why didn't you easily add them to the log instead of the suggested to be deleted PIDs?

[GAH111]

The last 2 PID are Coolant temp and air intake temp. The 02 v is there, only bank 2 sensor 1 is within range, the others are all show .0xxx. The fuses to the MAF and 02 heaters are all good, I'm thinking i've got some bad ground wires probably from me trying to get all the stuff into the beauty cover after rebuilding the VANOS

[sapote]

The last 2 PID are Coolant temp and air intake temp. The 02 v is there, only bank 2 sensor 1 is within range, the others are all show .0xxx. The fuses to the MAF and 02 heaters are all good, I'm thinking i've got some bad ground wires probably from me trying to get all the stuff into the beauty cover after rebuilding the VANOS

My bad. For some reasons I didn't see the log that way on that day
I cross out those pid that are not needed.
All O2 sensor signals look wrong. M3 doesn't use wide-band for pre-cat sensors so I expect to see the signals swing from 0.2v to around 0.7v; Your signals look almost like from wide-band sensor with very little voltage swing.

Pre-cat should look like this:


Yours:

[sapote]

You should add Fuel system 1 and system 2 status pid to the log so I can tell DME runs open or closed loop control.