cam sensor/hall sensor

[HMS-S6]

Hello,

Sorry if i'm touching on an old question but i have searched and not found an answer!

The one remaining sensor on my problematic S6 is the cam position sensor, which is a cheap aftermarket item which was fitted when we had the car as a non runner four years ago - and since i didn't drive it before for all i know this is when my problem could have started!

So my qeustion is;

What function does this sensor have when the car is running?
I have read that it only is used on start up but, if disconnected boost is set at 0.4 bar so i find this difficult to believe
Does it controll fueling timing?

[johne]

What you have read is true, it is only used at start-up but if the ECU detects it is faulty then boost is said to be reduced.
It's only function relating to timing is at start up. When the ECU first detects the "TDC" pin on the flywheel (which isn't physically located at TDC) the ECU doesn't know which piston is on it's firing stroke so it uses the output from the cam position sensor to tell it. From then on the ECU "knows" where it is & doesn't need the cam position sensor again - until you stop & try to restart.
It has no function with fueling AFAIK.

John

[S2central.net]

Cmp sensor is mandatory for startup as said above. The crank reference pulse should arrive within the window of the cmp sensor. If cmp fails during running the ecu can continue with some safety limitations.

I am going to be scoping out these signals again very soon as part of esim project so I will post what healthy signals look like.

[HMS-S6]

Cmp sensor is mandatory for startup as said above. The crank reference pulse should arrive within the window of the cmp sensor. If cmp fails during running the ecu can continue with some safety limitations.

I am going to be scoping out these signals again very soon as part of esim project so I will post what healthy signals look like.

That would be very helpfull as i'm sick of blindly changing sensors as my vagcom will not work!!

[spions]

http://cgi.ebay.co.uk/AUDI-VW-CRANKS...item3ef936d431
Cut and put on old place.

[V6quattro]

There is a possibility to drive without the sensor. With a fake signal oid? Would be nice for a 7A head on ABY

[HMS-S6]

There is a possibility to drive without the sensor. With a fake signal oid? Would be nice for a 7A head on ABY

Yeh i was thinking of a poor/wrong signal but i'm probably clutching at straws as to why my cars still running **** after changing EVERY sensor!! and hose!!!

[S2central.net]

VAGCOM is rubbish for diagnosing many sensor faults... An oscilloscope is the weapon of choice here folks.

[S2central.net]

Enjoy - http://www.s2forum.com/forum/showthr...d=1#post498878

[HMS-S6]

Enjoy - http://www.s2forum.com/forum/showthr...d=1#post498878

Thanks for that! All i need now is the 'machine' for making those shapes!

[S2central.net]

Any decent diagnostics place will have an oscilloscope... Needs to be dual channel at least to verify things here.

[HMS-S6]

Any decent diagnostics place will have an oscilloscope... Needs to be dual channel at least to verify things here.

If anyone on here has one i'd be more than happy to pay for their time! Whenever i go somewhere i usually get the feeling i'm being 'rushed through' and would like someone woth an oscilloscope who is willing to take the time out to run the car under different conditions, reading EVERY engine sensor as i am convinced mt problem is electrical!

Any takers???

[S2central.net]

You can rent them from specialist firms but your next challenge is accessing the right ecu pins. I have the breakout box which is fantastic but others would need to open the connector hood and carefully hook up some probes.

Budget single channel scopes are 100 ish and you could probably pay similar money on eBay for a twin channel one.