(DIY or Garage?) Rough idle, white smoke, smell of petrol

den.sni92 · 08-18-2023, 02:32 PM

Hi all,

Without any warning my 35i all of a sudden lost the power whilst driving and started sounding VERY unhealthy.

I have parked the car for a day and then tried cold start to read the codes which resulted in clouds of white smoke, stink of petrol and lumpy idle.

Was hoping for somewhat straightforward DYI fix on the driveway now that weather is still warm.

Having scanned the codes I am now confused as to whether this is above my mechanical skills and the car will need to be towed to the garage.

The codes are

0029D0 - Combustion misfire, cylinder 4
0029F1 - Fuel pressure, plausibility
002A87 - Exhaust VANOS, mechanism
003100 - Boost-pressure control, deactivation
002C3E - Oxygen sensor 2 before catalytic convertor: Line fault
002CAB - Oxygen sensor 2 before catalytic convertor: Temperature

Car is on 79k miles.

If you were to attempt home fix, where would you start?

- Replace O2 sensor, clear codes and see if the car runs any better
- Replace injector
- Replace HPFP

Would a faulty Vanos solenoid cause all sorts of behaviour described and maybe that's the culprit?

Any help is appreciated.

Hejnfelt · 08-18-2023, 04:20 PM

Many options. Home repair most often requires trial and error in the absense of specialist tools. Swap cyl 4 plug to cyl 3 and coil to cyl 5, restart and see if problem moves to 3 or 5 or stays in 4.

3=plug
4=injector(maybe)
5=coil

Problem is you might hurt something or you may end up with completely different data and now you donno what to do.

Taking it to the right shop they'll probably diagnose the problem fast and have you running right.

B21 · 08-18-2023, 04:22 PM

Looks like two issues..oxygen sensor failure..could be burnt insulation…and a VANOS fault..

Cyl 4 injector could just be a victim..

3100 code is the DME throwing the towel in to save engine damage

Data logging will tell you if it’s HPFP

Could try the O2 sensor first

den.sni92 · 08-19-2023, 08:36 AM

Posting an update.

Swapped coil cylinder 4 with cylinder 1 and hey presto, all gone...
Reset the codes and then went for a drive.

Doesn't help with triaging what the root cause was until yet another code will come up.

In the meantime, I figure replacing all plugs and coils wouldn't hurt as those have not been done in a while.

08-18-2023, 02:32 PM	#1
den.sni92 Registered 0 Rep 3 Posts Drives: Z4 35i Join Date: Aug 2023 Location: UK iTrader: (0)	(DIY or Garage?) Rough idle, white smoke, smell of petrol Hi all, Without any warning my 35i all of a sudden lost the power whilst driving and started sounding VERY unhealthy. I have parked the car for a day and then tried cold start to read the codes which resulted in clouds of white smoke, stink of petrol and lumpy idle. Was hoping for somewhat straightforward DYI fix on the driveway now that weather is still warm. Having scanned the codes I am now confused as to whether this is above my mechanical skills and the car will need to be towed to the garage. The codes are 0029D0 - Combustion misfire, cylinder 4 0029F1 - Fuel pressure, plausibility 002A87 - Exhaust VANOS, mechanism 003100 - Boost-pressure control, deactivation 002C3E - Oxygen sensor 2 before catalytic convertor: Line fault 002CAB - Oxygen sensor 2 before catalytic convertor: Temperature Car is on 79k miles. If you were to attempt home fix, where would you start? - Replace O2 sensor, clear codes and see if the car runs any better - Replace injector - Replace HPFP Would a faulty Vanos solenoid cause all sorts of behaviour described and maybe that's the culprit? Any help is appreciated.
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08-18-2023, 04:20 PM	#2
Hejnfelt Private 11 Rep 59 Posts Drives: ‘13 BMW Z4 sDrive 35is Join Date: May 2023 Location: Tallinn iTrader: (0)	Many options. Home repair most often requires trial and error in the absense of specialist tools. Swap cyl 4 plug to cyl 3 and coil to cyl 5, restart and see if problem moves to 3 or 5 or stays in 4. 3=plug 4=injector(maybe) 5=coil Problem is you might hurt something or you may end up with completely different data and now you donno what to do. Taking it to the right shop they'll probably diagnose the problem fast and have you running right.
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08-18-2023, 04:22 PM	#3
B21 Captain 153 Rep 611 Posts Drives: E89 Atacama Yellow 35is Join Date: May 2022 Location: Scotland..God’s own country iTrader: (0)	Looks like two issues..oxygen sensor failure..could be burnt insulation…and a VANOS fault.. Cyl 4 injector could just be a victim.. 3100 code is the DME throwing the towel in to save engine damage Data logging will tell you if it’s HPFP Could try the O2 sensor first __________________ Much modified 2011 Atacama Yellow 35is…previously a much modified 2012 Atacama Yellow 20i MSport Change history here… https://www.dropbox.com/s/8h1vabklgz...0List.pdf?dl=0 Build thread here… https://z4-forum.com/forum/viewtopic.php?t=131886
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08-19-2023, 08:36 AM	#4
den.sni92 Registered 0 Rep 3 Posts Drives: Z4 35i Join Date: Aug 2023 Location: UK iTrader: (0)	Posting an update. Swapped coil cylinder 4 with cylinder 1 and hey presto, all gone... Reset the codes and then went for a drive. Doesn't help with triaging what the root cause was until yet another code will come up. In the meantime, I figure replacing all plugs and coils wouldn't hurt as those have not been done in a while.
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