Cam sensor again

[orsum]

About 6 months ago I replaced the cam sensor with a Bosch unit part number 0 232 101 020 and all was well.

Yesterday the car started and then shut off after about 0.5 - 1 second, the rev counter just dropped to zero. I tried to start the car about 5 times the same thing happened.

The last time I tried I put my foot on the accelerator started the engine and took it to about 4000 rpm, when it shut off I turned the ignition off and back on before the engine was stationary the engine kicked back into life and kept running.

Today the car started fine.

Any ideas on what the problem could be this time?

I also took the old sensor out of my spares box and had a good look at it. In the air gap there were some very very very fine iron filings which looked like they could have created a magnetic path which basically could have kept the sensor switched thus a possible reason for not working.

I will be testing the old sensor today.

[UrS4boy]

Can you pull the codes?

Have a look at this:

http://forums.quattroworld.com/s4s6/msgs/323125.phtml

[orsum]

I have been putting off the diag software and cables for the S2 and my S4 B7, I have just placed the order for a HEX-USB+CAN Interface software & cable kit.

Will pull the codes as soon as it arrives.

Checking my old sensor the colours are black, pink and light green any idea of which the supply, ground and signal wire are.

ADVICE ON WIRES NOT NEEDED JUST FOUND WHAT I WAS LOOKING FOR

[orsum]

Just tested the hall sensor I removed six months ago and its working 100%.

It definitely appears that a build up of iron filings/iron dust build up caused the sensor to not switch off.

I wonder how many have been replaced in error because of this. Worth checking before replacing.

Anyway this throws up another issue were did the iron dust/filings come from further investigation on this will be needed.

Is it the same problem now!!

[bazburn]

Just tested the hall sensor I removed six months ago and its working 100%.

It definitely appears that a build up of iron filings/iron dust build up caused the sensor to not switch off.

I wonder how many have been replaced in error because of this. Worth checking before replacing.

Anyway this throws up another issue were did the iron dust/filings come from further investigation on this will be needed.

Is it the same problem now!!

What head have you got? Modded 7A maybe? I had this problem and it was the sensor bracket in the wrong place by a gnats whisker but caused the wheel to slightly rub, hence iron filings...if not is cam wheel perfectly round where it goes through sensor?
HTH

[orsum]

Standard ABY no mods yet, still waiting for all the parts to arrive for the conversion to RS2.

Took great care when the sensor was replaced but will check the gap again when I do the timing belt and cog change.

[UrS4boy]

G40 Cam Sensor Info

G40 Cam Sensor Info:

http://forums.quattroworld.com/s4s6/msgs/22580.phtml

Check that you don't have a bent cam sensor shutter wheel:

[orsum]

Started with no problem on the way home from work.

Can a low charge battery cause this type of start / stop

[UrS4boy]

"Proof" that an intermittent G40 Cam Sensor failure will stop an engine while driving

Started with no problem on the way home from work.
Can a low charge battery cause this type of start / stop

A low battery will cause a non-start because the crank speed is less than 13 RPM and therefore the ECU will not trigger the J17 Fuel Pump relay.

*IF* you took the time to read *ALL* of my G40 info that I linked you to, you would have found this:

"One thing to watch for is an intermittent G40 Short to Ground (VAGcom code 00515). In this case, the G40 is failing and that short to ground will stop the engine from running, despite what we *think* the ECU should do with the G4 Crank Position Sender signal to keep the engine running. Sometimes reality is stronger than theory. Here is a link to a documented case that the 00515 intermittent G40 short to ground code will stop a running engine. "

And the link was this, based on IrishS2's experiences:

"Proof" that an intermittent G40 Cam Sensor failure will stop an engine while driving:

http://forums.quattroworld.com/s4s6/msgs/139944.phtml

Screen shot courtesy of IrishS2

[orsum]

Thanks