so lads what does the hall sender do ?

[DAVIDP20V]

This morning i moved the car after it was sat for a couple of hours (cool engine) to another space. Came back 20 mins later to move it back again and she wouldnt start !

i tried 5 mins later and it still wouldnt start !

i tried 10 mins later and vrooom of she goes !

Then driving home from work boost was a bit jumpy then suddenly she wont boost more than 5 psi ! (mech boost ??) BTDT !

This happened to me about 6 months ago which i thought was rectified by spark plug change but back then she didnt really have a starting prob.


so tommorow i will check wgfv + dump valve + plugs + boost leaks any other ideas ?

i have also read about the hall senders playing up a bit, but would this cause boost probs ?

cheers in advance dudes !

[spink]

I had similar symptoms on my car(without the lost boost), and it was the hall sender.Dont often fail i have been told.

[DAVIDP20V]

it starts ok now !?! but has not a lot of boost ! Are the faults connected ?

[Keeper of The Kitten]

By hall sender are you saying hall effect switch? That would be a crank speed sensor, yes? If they fail, starting becomes impossible! Not sure how it would relate to boost though?

__MDC__

[Kartis]

My hall sensor fails during load. vag com says "signal shorted to B+" (ABY engine)
has changed hallsensor, campulley, sensors on flywheel without sucess. loosing 6* ignition on the faultcode so i realy need to fix this.
Thinkin that if u use original boostcontrol, relaxes the boost to. (limp home mode)

[caterpillar]

it may be the svitch in the car.they are very bad sometimes.

[DAVIDP20V]

what switch caterpillar ?

[porkkis]

ignition switch

[Kartis]

mm.. what has the ignitionswitch to do with the hallsender?

[Keeper of The Kitten]

Ignition switches get damaged at the end, being plastic or white metal or something nasty, so the end chews up when you turn the key - and given enough time, it won't turn the switch to it's full travel. I've had this on my S2 and on an 80 I used to have. It's a fair point!

__MDC__

[DAVIDP20V]

ignition switch no boost ? ..............i am lost in a strange world

[porkkis]

Ignition switch could be the reason for the starting problems, the boost problem is (or could be) another case.

[Kartis]

Did u pull any faultcodes?

[S2central.net]

Let me interject with some sanity if I may...

The device generally referred to as the 'hall sensor' on the S2 has the task of telling the ECU about the position of #1 cylinder. It needs these, along with TWO other sensors on the crankshaft, to determine the correct ignition point.

On a 3B or RR, the hall sensor resides inside the dissy. On an early AAN engine an otherwise empty dissy houses the hall sensor. On late AANs and all ABY / ADU engines, the hall sensor resides underneath the camshaft sprocket. In all cases the hall sensor is referred to as G40 on the schematics.

Whilst the ECU is intelligent enough to keep the engine running after failure of G40, it will never be able to start the engine with a faulty G40 as the ECU is unable to establish to correct position of the engine.

Failures are NOT uncommon and they are prone to failure at high temperature. A miraculous cure is often found by just letting the car cool down and trying again.

On a totally unrelated note, failure of ignition switches is also well documented for the Audi 80 & Coupe of our genre. This can cause all manner of heinous no-start conditions.

Pull fault codes !


Paul

[SR71]

Exactly as Paul says.

The car would start from cold and run. You'd stop for gas, and it wouldn't start. You'd crank forever and nada.

Let it cool and it'd start again.

Did this sporadically for about two weeks until one day it wouldn't start at all.

£550 later and she'd start fine again (and that was with a 10% discount on labour).