Cam sensor

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Vodka0tter

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Kinda confused on what the cam sensor really does.

I installed a Blueprint Engines 383 in my '97 C1500. I actually missed the connection to the cam sensor and ran the truck for several weeks until I went to get the cam retard offset dialed in at the dealer. I was shocked to hear I did not connect the wire to the distributor but the truck seemed to run fine.

I read on the interweb the cam sensor "really" just helps identify the cylinder if a misfire occures but dont know if thats true? I do know the truck ran fine with the sensor not connected at all.

I live in a "visual" emissions only area and my inspection guy is kinda blind so I can get away with a lot.

If I really dont need the sensor I may opt to dump this POS vortec intake and move on to something else. I already have evap, EGR, pretty much everything on the intake deleted. Also I am guessing I could/should use a light for timing...

Any one know exactly what the sensor does?
 

delta_p

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My manual says the cam sensor and the crank shaft sensor are used to detect if a misfire has occurred. If a deceleration of the crankshaft occurs that is not part of normal engine speed reduction, the VCM will compare the declaration with engine speed and load info. If it decides a misfire occurred it has a routine it goes through to use the crank shaft sensor and the camshaft sensor to determine which cylinder or random misfire to set DTC. VCM also uses information from the ABS to determine rough road condition which may have caused engine deceleration. etc..........
 
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As per GM service information-

Camshaft Position (CMP) Sensor




The camshaft position (CMP) sensor is located within the distributor. The operation of the CMP sensor is very similar to the crankshaft position (CKP) sensor. The CMP sensor will provide one pulse per camshaft revolution (1X signal). The loss of this signal may not affect the driveability of the vehicle, but will affect the type of control the VCM has on the fuel injection system. If this signal is lost, the VCM will pulse the injectors bank to bank instead of each individual injector at a time. The VCM also utilizes this signal in conjunction with the crankshaft position in order to determine which cylinders are misfiring.
 

Vodka0tter

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Thanks Philip, good info. So fuel efficiency is the big impact of the entire bank being pulsed as opposed to the individual cylinder?
 
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Maybe slightly improved economy, but sequential injection mostly improves emissions and smoother operation at idle speeds from what I have read. Also keep in mind most sequential port injection systems switch to bank to bank once rpms reach a certain point.
 

Vodka0tter

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Okay. Yeah, as mentioned I ran for a while without being plugged in and didn't notice any difference. Mild lope at idle made the issue hard to detect I suppose.

Good info - thanks man!
 
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Also thought I would mention that turning the distributor does not effect timing, you will increase rotor to cap terminal gap to the point it will start to crossfire to other cylinders, but this really won't change your timing much, which is based off of crankshaft position. You can run the vortec distributor with other types of intakes and retain your camshaft position sensor, biggest challenges doing this is rewiring for normal injectors, plumbing the fuel system and making sure your intake is compatible with the a/c compressor/mount.
 
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