Pontiac Problems? Ask a Mechanic for Answers ASAP
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2078 will not cause a no start issue, but the 0315 can. The crank position has to be learned via a scan tool. The PCM uses this signal to know when to pulse the ignition system. Since your back firing that means the plugs are firing at the wrong time or valves are stuck open from possible timing issues.
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Yes many upper level scan tools can do a crank relearn.
Since you have disconnected the computer and or battery and or swapped the engine, the computer has lost the memory of the crank position. Swapping the computer now will not resolve this.
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