Cam sensor troubleshooting

Give input on tuning as well as any tips and tricks you may have. Also feel free to share base mapping files for various engine types.
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FrankCorrado
Posts: 120
Joined: Tue Jul 26, 2011 7:45 am
ECU Model: S80 Pro
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Cam sensor troubleshooting

Post by FrankCorrado »

Well, I would like to list what to check for when we have cam sensor errors.

We need to make sure the mechanical parts are working and that the magnet (if the sensor is magnetic) does trigger a voltage pulse. Can we check what voltage it triggers? Do we know what it should be?
We need to make sure the wiring to ECU box is correct.
We need to make sure the signal is not affected by other radio frequencies around, so shielded cables are important and sometimes other tricks. (I use a round magnet designed to reduce radio frequencies, around the cable, can't remember the name of that, it's the same thing monitor cables for computers have, close to the connector)
We need to check in the Diag Panel that we don't see errors cumulating.
We need to setup the configuration in the Sequential Injection panel for the right tooth, which we can see in the Diag Panel, bottom right section. That is where the ECU detects the sensor.

But what else? Cuz there certainly is something else. In my situation, I ran the whole summer without cam errors, not enough at least to cause issues. Then I left the car aside for 2 weeks cuz I was on something else and could not use it. I did not do any mechanical adjustment to the car since maybe May, I did not modify the DTA settings other than CL, target map, startup map and playing around in June with the injector angle (which I froze at a fixed number in July). After the 2 weeks, this was about 1.5 weeks ago, I started the engine and I got cam sensor errors adding up at every turn. Car was stalling within seconds. There was nothing to do, I had to switch to batch fired. After 30mins drive I stop the engine, started up 1h later and cam sensor was perfect! Car rest for 1.5 weeks or so, started up this w-e, ran fine wit no errors. Stop, started about 6h later, at 38C water, after 2mins drive the car was heavily bucking and as soon as I lift off gas, rpm was dropping and engine stalled. I restarted and got bunch of errors accumulating at every turn. Switched to batch again and it was ok (ok my fuel map is all wrong then, but it was not stalling due to cam errors).

Sometimes the errors pile up as soon as I start the engine, sometimes the engine runs fine but within 5mins driving stalls at a stop or light, sometimes within 5mins driving it bucks and stalls. Sometimes it runs all fine for the whole time. Why the hell do I always get complex intermittent issues?

So what else could I check other than above?
I use the MASK WINDOW in the Sequential settings, so that the ECU only looks inside a specific window for the signal to pulse, reducing errors of radio frequencies outside the tooth window the signal should pulse at. Maybe I can try to narrow the window or widen the window, that's another thing to look for.

Is there anything else?

tnx
Frank
VW Corrado VR6 Turbo GT3582R getting into a super light kit car
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VR6Turbo
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Re: Cam sensor troubleshooting

Post by VR6Turbo »

I think that thing they clamp around cables is called an RF Choke. You shouldn't really need anything like that to be honest.

Have you tried a new cam sensor? If you're getting intermittant signal issues, it could just be a failing sensor.

The factory ECU switches to a batch map automatically in the event of a cam sensor issue, which is just as complex, if not more so, but you're just not aware of it. It's only because you are now exposed to a fully open ECU things seem more difficult. It just means the ECU isn't holding your hand Frank. You have to get your hands dirty and figure out the problem unfortunately.

Nothing's changed you say. So by process of elimation, try a new sensor first and if the symptoms persist, you will need to check your wiring!
FrankCorrado
Posts: 120
Joined: Tue Jul 26, 2011 7:45 am
ECU Model: S80 Pro
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Location: Montreal, Canada

Re: Cam sensor troubleshooting

Post by FrankCorrado »

That's true, the sensor itself, I didn't think about it.

It's new since last year, but who knows, it may be faulty or maybe we broke it somehow when we forced it in the first time when I had the wrong side plate, remember. Forced it with a rubber hammer. But I thought those things were either working or not working at all.

I'll try to find another one.
Please, not the stupid wiring, I'm sick of playing with wiring. loll
Frank
VW Corrado VR6 Turbo GT3582R getting into a super light kit car
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VR6Turbo
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Re: Cam sensor troubleshooting

Post by VR6Turbo »

I keep a spare cam sensor and allen key in the glove box! 2 mins to change.

Crank sensor is game over though. Can't get to that on the road side!
FrankCorrado
Posts: 120
Joined: Tue Jul 26, 2011 7:45 am
ECU Model: S80 Pro
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Location: Montreal, Canada

Re: Cam sensor troubleshooting

Post by FrankCorrado »

No? I thought you (Kev) could even replace a piston ring and change the crank on the road side... bare hands no tools... using a spare engine somewhere in your trunk... at night... when ran out of fuel... and forgot your money and credit cards... lolll :D
Frank
VW Corrado VR6 Turbo GT3582R getting into a super light kit car
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FrankCorrado
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Re: Cam sensor troubleshooting

Post by FrankCorrado »

Ok some more ideas on troubleshooting cam sensor issues. But also I need more! loll

In the settings (Sequential) you can remove the cam noise mask and see what it does. You can also widen the window if you use noise mask or reduce it to the bare minimum. Of course you need to know from the diag panel or oscilloscope test at which tooth the cam sensor is detected by the ECU.

But, if you want to go deeper into the troubleshooting, which I need to, do an oscilloscope test. If it does NOT find the cam sensor (like me!!!), there is something wrong either in the wiring, ECU or mechanical.

If you checked your 12v power and it's fine, if you checked resistance on your signal wire to the ECU and it's fine, if you checked your ground (PIN21 if I recall) and it's fine, if you did the oscilloscope and it does NOT find the cam sensor, then you need to test the installation offline.

Does anyone know or can think of how?
I mean if I remove my sensor but leave it plugged, can I use a magnet and pass it over the sensor? Then how can I see the ECU detecting the signal??

I am out of idea on that test but I need to do it, cuz everything else when online (engine cranking and running) has been checked and the wiring has been checked, but not manually triggering the signal.

tnx
Frank
VW Corrado VR6 Turbo GT3582R getting into a super light kit car
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VR6Turbo
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Re: Cam sensor troubleshooting

Post by VR6Turbo »

So just to confirm:

1) You get no pink cam trigger line in the cranking scope.

2) You are using flywheel mode 0 in General Engine settings.

3) The cam sensor is wired as follows:-

Pin 1 - Switched 12V
Pin 2 - Signal (to Pin 23 at ECU sensor plug)
Pin 3 - Ground (to Pin 33 at ECU sensor plug)

4) Sequential is enabled.

If all of the above is true, then I still say you have a wiring fault or a duff sensor!

When cranking, there should be a dirty great voltage spike coming out of Pin 2 every 2 crank turns, which your should be able to see with a voltmeter. Have you confirmed there is a voltage coming down this wire at the ECU end?

If you're seeing a voltage end to end and everything is correctly wired and setup in software, then it does sound like there is an internal fault with the unit.
FrankCorrado
Posts: 120
Joined: Tue Jul 26, 2011 7:45 am
ECU Model: S80 Pro
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Re: Cam sensor troubleshooting

Post by FrankCorrado »

VR6Turbo wrote:1) You get no pink cam trigger line in the cranking scope.
Correct. Not anymore!
VR6Turbo wrote:2) You are using flywheel mode 0 in General Engine settings.
Correct, can't change that otherwise it doesn't start.
VR6Turbo wrote:3) The cam sensor is wired as follows:-

Pin 1 - Switched 12V
Pin 2 - Signal (to Pin 23 at ECU sensor plug)
Pin 3 - Ground (to Pin 33 at ECU sensor plug)
Not quite.
Pin 1 is 12v yes.
Pin 2 is Signal, yes, but going to PIN22, not PIN23. PIN23 is the hall sensor effect, it's not hall it's magnetic, like yours. :)
Pin 3 USED to be to PIN33, stopped working. This w-e I changed it to PIN21 like on the diagram. Still not working.
VR6Turbo wrote:4) Sequential is enabled.
Yes, but now switched off cuz it doesn't work. lol But I do switch it on when I test the cam sensor (I use a map that I load and it's ON and I see bunch of consecutive cam errors after engine starts and it dies).
VR6Turbo wrote:If all of the above is true, then I still say you have a wiring fault or a duff sensor!
2 sensors and same result.
Wiring fault, how can I check that? The signal wire from both ends has no resistance. So to me the wire is not faulty.
The pin is inserted as far as all the other pins in the ECU's plug, so to me it looks like the pin can connect like it should inside the plug.
I measured 12v no problem on the sensor's plug.
The above tests have been made a couple of times to ensure consistency.
I do not know what else to check as far as wires go.
VR6Turbo wrote:When cranking, there should be a dirty great voltage spike coming out of Pin 2 every 2 crank turns, which your should be able to see with a voltmeter. Have you confirmed there is a voltage coming down this wire at the ECU end?
The RPM pin?
How can I checked that if the plug is plugged to the ECU?
VR6Turbo wrote:If you're seeing a voltage end to end and everything is correctly wired and setup in software, then it does sound like there is an internal fault with the unit.
If I end up there, I'll have to ship it to DTA for testing.

But, you know what? Allan says there is no 12v on magnetic, it is only for Hall effect! That contradicts the diagram and means I cannot use VW OEM's sensor configuration, which you did use 100% perfectly for years and thousands of miles. Interesting, isn't it? :)

His suggestion:

You cannot have a 12V magnetic cam sensor. It either needs 12V in which case it is hall effect or it is magnetic without a 12V supply.

Run the engine by:-

Turn OFF sequential Injection
Turn OFF one coil per plug
Turn ON twin spark in general engine settings.

Put a real oscilloscope on the output of the sensor with the engine running and look at the signal.
Frank
VW Corrado VR6 Turbo GT3582R getting into a super light kit car
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VR6Turbo
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Re: Cam sensor troubleshooting

Post by VR6Turbo »

Erm, the VR6 cam sensor *IS* a hall sensor Frank :lol:

Allan is right, you don't have powered magnetic sensors!

I hope you haven't wrecked the ECU because Pin 22 is expecting < 2V, not 12!!

To test the end to end wiring, do as you suggested. Take the sensor out of the head but leave it connected. Wave a peice of steel in front of it and you should see a voltage at the ECU pin. If not, there's your answer :D

Pin 21 and 33 are the same thing internally, so that shouldn't make a difference.
FrankCorrado
Posts: 120
Joined: Tue Jul 26, 2011 7:45 am
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Re: Cam sensor troubleshooting

Post by FrankCorrado »

VR6Turbo wrote:Erm, the VR6 cam sensor *IS* a hall sensor Frank :lol:

Allan is right, you don't have powered magnetic sensors!

I hope you haven't wrecked the ECU because Pin 22 is expecting < 2V, not 12!!
Mother freaking darn crap of my ass!!!!!!!!!!!!!!!!!!!!!!!!!

Well, it better be that the problem, that would fix it! :)
That would explain why I had issues at first with that sensor and why it started to run bad gradually until not working at all.
I will ask Allan what can happen to the ECU if I send 12v instead of 2.
VR6Turbo wrote:To test the end to end wiring, do as you suggested. Take the sensor out of the head but leave it connected. Wave a peice of steel in front of it and you should see a voltage at the ECU pin. If not, there's your answer :D
Exactly. I'll do that and then switch it to PIN23. I'll post results hopefully within a week.

BTW, Allan says hall effect sensors can be either 5v or 12v and he said we could use 12v on the PIN23, which is exactly what you mention here. So the diagram says 5v on PIN23, but that is not 100% accurate, it could be 12v as well. Since VW uses 12v and I saw 5v on the diagram, I then thought I could not connect it to PIN22. I would be so happy if that is the problem!
Frank
VW Corrado VR6 Turbo GT3582R getting into a super light kit car
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