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Subaru cam sensor stays triggered


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I have a EJ25 motor, with the factory cam position sensor on it. I am running on a monsoon ECU

The crank position sensor is hooked to trigger 1, and it seems to behave as I would expect.

The cam position sensor (hooked to trigger 2) seems to get triggered, and stays triggered for 5 seconds or so. (See attached log)

I tried other replacement sensors, and they seems to behave the same way.

Am I not understanding what this sensor is doing here? I would expect to see a around 5 triggers per rotation of the cam.

Thank you!

cam-sensor-stays-triggered.llgx Fedi - Subaru WRX V3-4 G4X Xtreme Plugin.pclx

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If you are talking about the "trig 2 signal" runtime, that would be normal, this parameter is just telling you an acceptable voltage has been received on the trig 2 pin.  

If you have a trigger issue, please do a trigger scope while cranking and attach that here. 

I notice in your map you are using "Subaru V1-6" trigger mode, I would expect you should be using the EJ25 mode unless you have fitted EJ20 triggers to it.

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Connect to ecu.  Go to >ecu controls>trigger scope.  Crank the engine, click the capture button in the triggerscope screen while the engine is cranking.  Save the trigger scope file, attach here. 

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Okay, that helped me. That scope function is really nice.

It appears that my camp position signal is good as I have the cams as seen here: https://www.ultimatesubaru.org/forum/topic/170824-36-2-2-2-trigger-wheel-image/

That is, the pattern is this 1-3-1-2 pattern.

So, the triggers look good, but the ecu is not firing the injectors, or the ignition coils now.

I can run tests on both, and they work.

I am not quite sure what I have configured wrong. It looks like the ecu should be firing the injectors and spark plugs.

TriggerScopeLog - sensors look good.llgx ferdi - Subaru WRX V3-4 G4X Xtreme Plugin.pclx PC Datalog - 2023-01-13 3;52;17 pm.llgx

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The cam sensor is wired incorrect polarity.  You need to swap the +/- wires at the cam sensor plug.  

Your trigger voltage is quite low also, so I would lower the arming thresholds a little to this example:


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Alright. That seemed to have changed the behavior. I get one fire, then nothing.

The cam and crank sensors were wired inverted of eachother.

I switched one, and now they both match, so, I either have both of them correct, or, both are backward.

Could you tell me how you knew that the cam sensor was wired wrong? Something about the shape of the waveform?


PC Datalog - 2023-01-14 4;40;42 pm onefire.llgx

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It looks like the ecu is happy with the trigger now, although cranking RPM is a bit slower than expected.  Can you give a bit of detail about the engine - what size injectors etc.  


1 hour ago, felare said:

Could you tell me how you knew that the cam sensor was wired wrong? Something about the shape of the waveform?

Have a look t the help file page >Wiring Information > Input Signal Wiring > Trigger Inputs > Reluctor/Magnetic Sensors.  The waveform should first rise as the tooth approaches the sensor, then sharply fall through zero (zero crossing is the exact center of the tooth), then negative voltage as the tooth moves away from the sensor.   If you look at the single tooth on your cam it will be most obvious that yours goes negative first, then rises across zero.

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I have stock injectors that came with the head. They should be the injectors off of a 2001 subaru forester 2.5l naturally aspirated head.

I am unable to find much data on these though, so, I do not know what flow rates these are or anything.

I am happy to get new ones if that would help.

I am attempting to run in a naturally aspirated configuration with this car for now.

As for the cranking RPM. Maybe that is due to a small battery in this car? It does seem like the 12 volt battery is getting weak.

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OMG! That was it!

I had to turn the injector master fuel up to 40 before it would idle, but now it runs!!!

Thank you so much for the help!

Now to package things up and spend some time with a pro tuner, and I just ordered larger injectors.

To recap for others on this thread:

1. My base understanding of what the trigger 1 and 2 states are was wrong. They go high when receiving a valid signal.

2. I had one of my cam sensors wired backwards,

3. The original cams from the original subaru forester motor were correct, needing to use the "subaru V1-6" configuration

4. My stock injectors are rather small compared to what the shipped tune wants, meaning that I needed to crank the master fuel value up.


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