Cam sensor

[your_I.D.]

What is the exact function of the cam semsor? The crank sensor is for ignition and injector timing. Is the cam sensor just a signal to verify to the PCM that the cams are turning?

[pepsi_coke]

A target magnet, attached to the end of the cam shaft, has different poles. As the camshaft rotates, so does the magnet. The cam sensor has identical electrical circuits going to it, just like the crank sensor. As the cam (and magnet) rotate, the voltage fluctuates. Once the ECM has both sensor inputs, it can determine which coil to control and which injector to energize.

-Jay

[your_I.D.]

Well thats not how the 95 cam is set up. It has one raised up steel block on the cam. About 1/4 inch square and 1/4 inch high. No magnet on cam. So being there is only one trigger point. I dont think it has much to do with ign timing and injector timing.

[bszopi]

From a 3100 GM Supplemental Manual...

"The cam sensor is the synchronizing trigger for sequential fuel control. During cranking, the PCM provides three prime pulses at all the injectors based on the 3X signal for startup. It then looks for the falling edge of the cam signal to trigger injector #4. After this, the PCM primarily uses the 3Xsignal from the ignition module to time the sequence firing of the individual injectors."

In other words, the cam sensor tells the PCM when to start firing the injectors for proper sequential fuel injection. After that, it really doesn't do much. But if it wasn't there (or not working properly), the injectors could possibly not fire in the correct sequence.

Oh, and the magnet this is somewhat correct. Except the concept was wrong. The sensor is a hall effect sensor, and the raised portion of the cam triggers the hall effect sensor. Basically, when something (the trigger) passes close to the sensor, the sensor creates a square wave in relation to the amount of time the raised portion is close to the sensor. In 96, GM inverted the cam trigger on the 3x00s. Now, it sensor was seeing an object close to it except for a small portion where there was a notch located, therefore once again creating a square wave.

[your_I.D.]

Guess I should have made clear what engine model was of cam sensor in question. Does this include the 1997 LQ1 OBD II system?

thx for the info

[bszopi]

A 97 LQ1 is still SFI, so the operation of the sensor will be almost identical.

[blackbombshell95]

I just replaced mine. my car threw a code for it. 0017 i think is the code.

Does having a non functioning cam sensor affect acceleration at all?