Would appreciate some help - rough idle and vanos codes

[8900120d]

Hi guys,sorry about the long post!

ive been trying to determine what the problem is with my car, i originally thought it was the HPFP, but now im not 100% sure, would appreciate some opinions.

The story:

(a few months ago i got a 2a98 & 2a9a code, this was fixed by cleaning the vanos sensors)

335i n54 6at 2007:
BMS JB4
BMS DCI
BMS OCC
Big tom intercooler
Upgraded oil cooler
HKS Exhaust system
Pure stage 2 turbos
Brand new turbo oil and coolant pipes
RB turbo oil drain pipes
RB pcv valve
RB pcv valve cover
New vac lines all round
VTT inlets
OEM spark plugs with <2k miles
VRSF Downpipes

BMS pump flash (MHD)
BMS Map 2

Background info:

ive been driving the car with the above mods for 1k miles now, running at default jb4 map 2 PSI. the car drove fine, the only thing i noticed was that on start up, at idle, the car would do the following:
. run at ~800rpm for a few seconds
. drop down to <500rpm for 2-5seconds (at this stage the car shakes violently)
. jump up to ~1500rpm
. settle down to ~650rpm (the whole process takes around 20-30seconds, once the car is at 650rpm, its ready to drive and drives fine)

i didnt think this was something to be concerned about as i thought it was tuning related and i was planning to get a custom tune anyway.

the car has always started on first crank.

got the turbos and other parts fitted to the car, and the car drove perfect and smooth for the several weeks 1k miles!

until....



Car broke down:

While cruising at around 50mph, my engine suddenly dropped Rpm and then stalled!
i immediately started it back up, the rpm's were bouncing around for a few seconds then it stalled again!
i tried starting it up several times after that, and each time the crank got longer and longer, until eventually the battery died (battery was crap anyway)

i thought it was a HPFP issue....



Is it the HPFP??:

1 week later, i bought a brand new battery and plugged it in. The car started up on the first crank!

• It stays running (RPM drops pretty low like its going to stall, but it doesnt stall)
• when i give some throttle, the revs build up great (not very smooth though)
• if i hold the pedal at 2k rpm, it holds great for a second or two, then the revs will either drop or jump itself.
• always starts on first crank

why is it that when the car broke down, the cranks were very long. 1 week later + a new battery, it starts on first crank. intermittent HPFP fault?

if the HPFP is faulty would i be able to give some throttle and rev the engine?



Vanos?:

ive got the vanos codes again:
2A98-Crankshaft inlet, correlation
2A9A-intake camshaft sensor

however i dont know how recently those codes appeared, as i dont scan my car very regularly (i know i should)

(previously these codes were fixed by cleaning the vanos sensors)

could a damaged vanos sensor cause the car to stall at a 50mph cruise?

could the vanos fault codes be thrown due to the engine cut off when my car broke down?

o2 sensors??:

5 months ago, after fitting my downpipes, i got the following code:
2c24 - Lambda proben in front catalytic converter, muddled

i triple checked all of the o2 sensor wires and connectors they are 100% plugged into the correct positions. i didnt notice any issues at all, so i ignored this fault code and drove like that for the past 5 months with no issues at all.

i thought this code may be thrown due to the downpipes being catless.

could this be a reason for the stall and rough idle? it was fine for the past 5 months!

Vacuum leak??:

another possibility is a vacuum leak, as i have the following code:
3100-Boost pressure control 2

i also noticed the vac canisters didnt 'hiss' when i removed the top vacuum pipe.

could a vacuum leak really cause the engine to cut off during a 50mph cruise??


BMS Pump Flash?

just to rule out the possibility of this being a tuning related issue or a timing issue, i have flashed the car back to stock using MHD. i get the exact same issue. so its definitely not a tuning issue.

Videos:



Below is a video i found on youtube, which shows the exact issue i had when my car broke down!




Below is my video of my car when i start it up (please note, i didnt touch the gas padal at all during the video) (stock BEF & JB4 map 0)




please help