Cm 870 cry for help

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(08-03-2019 )Mr Hagg Wrote:  I will say this if you had cpl 8519 and current 8520 and using ECM from old engine your biggest problem your facing is camshaft timing. 8519 is 4 degrees on injector cam and 8520 is 6 degrees so if you used a file for the 8519 i could see a real issue.

What kind of damage would that do too much fuel or not enough? If that's the case then it has been that way for about 40k miles... I for sure need to get that correct before anything else... I know the parts inside are the same I wonder what other timing and things like that are different