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View Full Version : M52 cam sensor anomaly, adjusts headlights and makes something *puff*



Uku
05-23-2024, 03:37 PM
So been trying to get M52 run well and one big issue seems to be camshaft sensor.

3 connector wires(without sensor plugged in):
Yellow - 0-0.3v? Goes to 0v fast when connecting probe (probably signal wire)
Black - 2,4v (I quess positive)
Brown - 0v (ground)
https://imgur.com/a/dma3qso

When i connect sensor, yellow and black stay 0v, tested volts also with cranking but will stay 0v.

So the total anomaly: Example, when i put needle with bare hands in yellow wire pin, headlights start to adjust and something starts working and making a bit louder pop sound(sounds like releasing pressure)

I read about US cam sensor recall but since im in EU, i think its totally original wiring.

Cam sensor is about 2 months old, HELLA sensor, driven maybe 1 mile or less in total, mostly idle tests done.

Somehow INPA still sees it changing angles(20-26°), but once engine is warm, it gives camshaft sensor error and angle will stay at 83 degrees, if engine cools down, it will show angles again until warm. So i guess there is short somewhere and that gives DME signal until it stops working.
Anyone got any idea if yellow wire goes straight to DME or is goes to some junction ? Then i know where to open up wiring.
At the moment it barely runs on maybe 2 cylinders and really rough(I guess it is because of cam sensor or i fried something with trying to get it working.)
Today had alot of new issues, gave crank position sensor, Fuel pump relay errors, CPS went away with clearing, but fuel pump relay stayed until it randomly started working again.
Tried giving it 12v from Vanos plug also, but that just basically stops all electronics, so didnt try that again.
Ordered new cheap cam sensor just in case.
E39 sedan 1996 March release.
WBADD31040BU09321
Maybe half a year ago i refunded 2 Delphi cam sensors because both didnt work, but now im thinking maybe i fried them without knowing there was an issue in my system lol.

ross1
05-26-2024, 09:17 AM
yellow ref wire should be 5v+

Uku
05-26-2024, 04:54 PM
Ye im not getting any volts. I guess it is to do something with it being early model.
Well all cylinders work with new cam sensor but it wants to stall easily and is rough idle, misfires. To get up in rpm, i have to keep moving throttle. If i hold pedal steadily at certain rpm, it will go down and get back up if i play with throttle.
Over 3k rpm engine seems run well.
I have gas system also installed and it runs more steadily on that, but i guess there are some differences from petrol to gas fuel.
Atm INPA shows only Vanos solenoid fault, but i dont think all this is because of that ?
Also i smoke tested intake and alot smoke comes out of CCV valve part, maybe that is the culprit ?
Should oxygen sensors take some time to get working ? Well when i look in INPA, they slowly climb down from 4v by 0.3 increments per second. Even if engine is warm, heaters take quite a while to jump from 25% to 80%(they jump not climb steadily)
TP works well.
And thank you for trying to help, any suggestion helps.

Uku
05-27-2024, 01:32 PM
Update: Got M52 running quite well again, problem was CCV vent seal was totally broken. For now i deleted that and now it runs quite well.
Main problem now is O2 sensors and need helping info with that.
The O2 sensors that are currently installed are new, but when they came and i plugged them in, wires in socket were in wrong order kept giving O2 sensor error. When i swapped wires to right order they show working.
But they adjust really slowly and takes a while to start working.
The O2's : https://www.ebay.co.uk/itm/325581076779
When they eventually get to around ~0.5v and if i give some throttle, they go up by 0.02 per second and i release throttle they go down by 0.02 per second until ~0.5v, which i dont think is normal.
They seems to be "Regulating probe" which im not sure if is the right ones for my engine.
So can anyone help me with which O2 sensors should i get ?