i compared pcm data readings with the egr plugged up and unplugged since the problem only occurs with the egr working. my timing is about 16 degrees at idle, cruising around 50-55 mph its about 30 degrees timing, this is with the egr off, well when i plug it up. my timing jumps up to about 40-45 degrees at low rpms. when i floor it it drops, 45 degrees of timing sounds like it is firing before the piston is near the top of the stroke, it is firing too soon. anyone have any input? it runs good at 30 degrees of timing adv. i am on the factory tune why would the factory tune be advancing the timing so much
