Cam sensor Signal

This section is dedicated to discussion of DTA engine control units such as the DTA E48 EXP, P8 Pro, DTA S40, S60, S80, and S100, as well as all things ECU related.
dloubser
Posts: 4
Joined: Wed Dec 27, 2017 7:24 am
ECU Model: S80 Pro
Firmware Version: 40.01

Cam sensor Signal

Post by dloubser »

Hi,

I have a S80 on a chevy small block V8 twin turbo setup. 60-2 flywheel, MSD 8514 Cam Sensor running on the cam in place of the distributor.
I have attached a scope of the crank and cam signals. Both my scope and the DTA scope with plugs removed.
I have also attached the MAP file. I am using flywheel mode 0

It does sync but I am getting cam sensor errors but no crank sync errors.

What I find strange is the cam sensor actual waveform. It rises and falls very slowly. Also does not seem to reach 0 Volts. The cam position as seen on the diagnostics screen does not only show one value but will jump around showing 355 then -195 and some other values.

Thanks!
Attachments
Crank_CamHall_02012018_1205_2.png
Chevy 383 TT Derek_02012018.map
(43.82 KiB) Downloaded 239 times
Scope_02012018_1402_ScreenCap.jpg
Rob Stevens
Posts: 1247
Joined: Thu Jul 28, 2011 4:10 am
ECU Model: S100 Pro
Distributor: None-Coil On Plug :)

Re: Cam sensor Signal

Post by Rob Stevens »

Indeed, looks like an incompatible cam sensor, looks like some sort of Hall proximity sensor rather than a switch. Has this device ever been known to work with DTA? Is it on the right cam input pin.
stevieturbo
Posts: 3577
Joined: Tue Aug 02, 2011 12:08 pm
ECU Model: No ECU
Location: Norn Iron

Re: Cam sensor Signal

Post by stevieturbo »

Definitely a weird signal and as it is, not one you would trust.

Open it up and see what is inside, as you might be able to adapt something. And is it definitely wired correctly, with correct voltage if hall type and wired to the relevant ecu pin as Rob says ?

In meantime unless it has really huge injectors it will happily run in batch fire mode without the cam sensor.
stevieturbo
Posts: 3577
Joined: Tue Aug 02, 2011 12:08 pm
ECU Model: No ECU
Location: Norn Iron

Re: Cam sensor Signal

Post by stevieturbo »

Or maybe something like this ?

https://www.eficonnection.com/home/prod ... bc-engines

By 1x, they're probably mirroring what the LS does, with a large 1/2 tooth for wont of a better description.
Rather than 1 small tooth, the tooth runs a full 180deg of the camshaft. So it can look a little odd, but it does still have only 1 rising, and 1 falling edge per cycle.
dloubser
Posts: 4
Joined: Wed Dec 27, 2017 7:24 am
ECU Model: S80 Pro
Firmware Version: 40.01

Re: Cam sensor Signal

Post by dloubser »

Thanks for responding so quickly guys. It is a very old unit discontinued by MSD. I will see if I can get some more info from them. The wiring was done as per a post I found about this unit.
It is linked up to the correct DTA Cam Hall pin yes.
Its not been confirmed to work with DTA.
The main issue is the slow rising falling edges.
I will need to see if this unit can be removed with the engine in the car as we have very limited space at the back, if not maybe build a simple conditioning circuit to at least get fast rising/falling edges? If these edges occur at a constant point it should be ok I guess.
Rob Stevens
Posts: 1247
Joined: Thu Jul 28, 2011 4:10 am
ECU Model: S100 Pro
Distributor: None-Coil On Plug :)

Re: Cam sensor Signal

Post by Rob Stevens »

Just do without for now, particularly if you not looking for extra MPG, crank trigger looks fine.
stevieturbo
Posts: 3577
Joined: Tue Aug 02, 2011 12:08 pm
ECU Model: No ECU
Location: Norn Iron

Re: Cam sensor Signal

Post by stevieturbo »

I guess a lot depends on where DTA actually sees the trigger as happening.

Whether rising, falling and at what voltage threshold.

A lot of ecu's the user can configure this, so you might be able to get away with it. But DTA it is not user configurable.
If you could make up a small circuit to have it switch a transistor that would give a good clean square wave then that would be an option. Cam sensor accuracy isnt so critical, but it needs to be half sensible.

If there is a modern setup that gives you a good clean single tooth with no messing about though....I know which route I'd be taking.

If your injectors are under around 800cc or so the engine will easily be quite happy batch fire though without the cam sensor. Larger than that and it will be dependent on a few other factors.
katana
Posts: 455
Joined: Sun Jan 27, 2013 6:08 pm
ECU Model: S60 Pro
Firmware Version: 29

Re: Cam sensor Signal

Post by katana »

Just thinking out loud........ if it is a Hall Effect signal shape should be squarewave - no rise and fall. This might imply the output is faulty but they usually fail either on or off not partially! Seems a simple device - surely easier to rig up a simple rotor and new Hall sensor...... if access can be achieved?
dloubser
Posts: 4
Joined: Wed Dec 27, 2017 7:24 am
ECU Model: S80 Pro
Firmware Version: 40.01

Re: Cam sensor Signal

Post by dloubser »

Sensor has strange behavior. As you can see on ScopeCamSensorStationaryVoltage_03012018.jpg before the starter engages the sensor
gives a output just below full voltage as it stopped on the ramp part. Confirming stevieturbo's notion that it acts like a proximity sensor that can measure distance.

Anyway I build a simple switching circuit with hysteresis and now have a square wave. Just need to shield the wires and increase the hysteresis up to 2V. If this failes I will rather replace the sensor all together.

Thanks.
Attachments
Crank_CamHall_WithCircuit_03012018_1522.png
ScopeCamSensorStationaryVoltage_03012018.jpg
Rob Stevens
Posts: 1247
Joined: Thu Jul 28, 2011 4:10 am
ECU Model: S100 Pro
Distributor: None-Coil On Plug :)

Re: Cam sensor Signal

Post by Rob Stevens »

'Anyway I build a simple switching circuit with hysteresis and now have a square wave' fair play that man :)
Looks sorted
There are some clever people out there,
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