Cam positioning sensor gone maybe?

[Nik0las]

what symptoms are if the cam sensor starts to die?

1. troble with warm start?
2. chanse of boost cut when you floor it?

[prj]

If it's Motronic, then you will always have a fault logged if it cuts boost.
Also, it won't be a "chance", if it's gone, it will be in limp mode until restarted.

[Nik0las]

it's not motronic but LINK - still uses the sensor for sequential ignition. I have to check the error log but hard worm start and boost cutting from time to time I would say that probly is time for new sensor. How good are those which EFIexpress is selling?

[prj]

No idea how the ECU is executed, but the hall sensor is only needed for starting the engine.
After that it is no longer needed - engine phase can not change.

Either way, you better contact LINK technical support, because I am pretty sure no one on the forum here can help you with this.

[UrS4boy]

No idea how the ECU is executed, but the hall sensor is only needed for starting the engine. After that it is no longer needed - engine phase can not change.

That *might* be true for Motronic but you stated that you don't know what LINK needs so you can't be sure what the situation is.

Motronic G40 Cam Position Hall Sender info

[UrS4boy]

How good are those which EFIexpress is selling?

Perfectly fine. And for $10 plus shipping they are excellent. Same senders that were part of the Group Buy a few years ago with BB Automacao. BB Automacao now doesn't sell in lots less than 100 pieces so Marc S. stepped up and took on retailing them to us.

[prj]

That *might* be true for Motronic but you stated that you don't know what LINK needs so you can't be sure what the situation is.

Try to gain some understanding what each sensor is used for in electronical engine control, and you will see that your statement is a bit ... let's say uneducated.

There are three trigger signals that are needed in modern 4 stroke engine control:

1. TDC signal from crankshaft.
2. Rapid signal for engine speed.
3. Zero signal from camshaft.

1. and 2. can either be handled via a pin and tooth configuration as done in the old Audi trigger, or you can use a timing wheel with a missing tooth, such as the 60-2 system. The missing tooth is used to signal TDC. This requires a bit more processing power though on the ECU side. Completely negligible by modern standards, but 30 years ago it was a little bit of a different story.

In a four stroke engine, because the crankshaft rotates at twice the speed of the camshaft, to know engine *phase*, needed for proper sequential injection and to run one spark per combustion event, you need a sensor on the camshaft.

Due to the flex in belts and chains, the camshaft signal is not good for pretty much anything else other than determining which phase the engine is in at startup. More than that, determining any kind of timing injection and so on from the camshaft zero point is silly as due to the previously mentioned flex it will be very inaccurate.

So this is why the camshaft position sensor is ONLY used on engine startup in any engine management system, which has been programmed by someone who knows what they are doing. Once the engine management knows the engine phase, it is aware of the phase until it is reset (meaning engine restart), and the sensor is not used anymore.

Thank you very much.

[UrS4boy]

Try to gain some understanding what each sensor is used for in electronical engine control, and you will see that your statement is a bit ... let's say uneducated.

Yes. I know nothing. You ARE A GOD who knows everything and no mere mortal can dare challenge anything you say.

[prj]

Yes. I know nothing. You ARE A GOD who knows everything and no mere mortal can dare challenge anything you say.

Instead of trolling, read my post, which explains everything.

[UrS4boy]

Intermittent G40 will stop a running AAN, ABY or ADU.

*IF* you are so infallibly smart Dmitri, AND you claim that the G40 is not used after the engine starts, how do you explain IrishS2's story?:

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

[quattro84]

Unless running wasted spark, which TS isn't since he states it is running in sequential mode, the hall sensor only has to work briefly during start.
I bet you can start it giving Motronic (or Link/ VEMS / ...) the pulse by hand if in the right timing window.

Like PRJ stated, the engine makes double the revolutions the camshaft makes (oh really?) so based on engine speed & zero point/TDC/reference point/... based on engine rev only it does not know if it is firing in compression or exhaust stroke and will not start (i hope...)

To reply on TS; check all trigger signals for plausibility, could be anything from dodgy sensor input (log would show) or software/controller issue (that would show as well) Use a double channel scope to log both trigger signals to find irregularities.

Tooth synch:


I would suggest to make an error log during such an issue, and contact your supplier. Dumping it here can be useful but based on previous comments i would not expect much...

[prj]

*IF* you are so infallibly smart Dmitri, AND you claim that the G40 is not used after the engine starts, how do you explain IrishS2's story?:

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

I don't care much for your stories or your snarky remarks.
All I know is that I have started a car which had the dizzy gear snapped off the camshaft by unplugging the hall sensor by touching the wires in rapid succession while the engine was cranking. Of course I did not accomplish this on the first try, and the neighbors did not take kindly to trying to start the engine in the wrong phase at 23:00 in the evening (hint: boom).

After this, the car drove 400km back to russia including a border check.
If you want to confirm this story, feel free to PM "Melber" on here.

As for that "Irish" guy's car - it clearly says 65535, meaning the controller memory was damaged, so during normal driving the ECU can reset itself sometimes every now and then, and while during normal driving you will just have a slight miss (because it will pick up again), if your hall sensor is dead it won't re-initialize.

I have disassembled the routines in Motronic and I know exactly how it works. If you look at the last signal on the diagram - this is what Motronic does internally and what it uses for absolutely everything after the engine is started.
And quattro84 here is a person who deals with engine calibration professionally as well.

You can throw your insults around all you want, you can bring anecdotal evidence, but the fact of the matter is, you are wrong. And you really don't like being wrong, do you?

[irishs2]

Just heard my name being mentioned all the way over here

My S2 has been fine since I changed G40 over a year ago, 65535 has not showed up since and my ECU didnt go pop. It was the short to ground causing issue. This could have been a wiring issue, but in my case it was G40 itself that was shorting to ground.

http://www.s2forum.com/forum/showthread.php?t=53468

Regards,

An "irish" guy.

[prj]

Just heard my name being mentioned all the way over here

My S2 has been fine since I changed G40 over a year ago, 65535 has not showed up since and my ECU didnt go pop. It was the short to ground causing issue. This could have been a wiring issue, but in my case it was G40 itself that was shorting to ground.

http://www.s2forum.com/forum/showthread.php?t=53468

Regards,

An "irish" guy.

Well, if there was short to ground on hall sensor, it is possible that it drained enough current from the ECU to cause all sorts of issues.

This is because the ECU sends the 5V reference output that it uses for absolutely everything (MAP sensor, boost/knock processor, fuel/ign processor, sequential injection processor I/O extender, 27C512 and 87C256 memory chips containing data and so on) to the hall sensor.
So if that is actually literally short to ground without any resistance, eventually the ECU will shut down it's 5V reference (and everything else) to prevent damage, thus the engine will die, and without a hall sensor signal it will not start up again.

Source: M2.3.2 factory electronic schematic from Bosch

[UrS4boy]

So a malfunctioning G40 *will* cause a running engine to stop running (which was my point) even though the ECU might not otherwise need it to run the engine.

Thanks for speculative explanation. Sounds reasonable.