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Originally Posted by GMMerlin
Not true, the PCM uses an Angle based timing strategy for determining crankshaft position, The A and B inputs are housed in 1 sensor and the angle that is created is how the timing strategy is determined.
If the sensor loses its A or B input, an intermittant loss of spark will occur, usually this will lead to a momentary misfire condition, but depending on engine conditions the engine could stall.
When the timing stategy is loss the PCM bases its timing on the crank sensor signal it saw..
The reason why your engine only acted up at a certain temp was because electronic componants are temp sensative and faults involving electronic componants can occur when the temp of a componant changes
What else do you want to know about the Premium V ignition system  |
I agree that misfire detection is important in that the primary purpose is to protect the CAT convertor.
All electronics components are heat sensitive and automotive is no exception. Until the engine warms up the PCM operates in open loop mode. It will switch to closed loop mode around 145 degrees referencing to the ECT temperature sensor and other pertinent sensor input parameters.
Also, when you replace a PCM module a case learn is recommended. I put in a re-programmed DHP PCM in my Grand Prix GTP over 2 years ago and did not have a case learn performed. It hasn't missed a beat nor have I encountered any misfire odb-ii DTC error codes.
BTW - The crank and camshaft position sensors are Hall-Effects sensors. The best way to check the outputs and timing is with an oscilloscope.