I had a shop install a Banks stinger plus system on my 2000 F-350 7.3 PSD. I got the truck back and it was a big difference. No check engine lights or problems. I got it back to the house and noticed they hadn't t-tap grounded the MAP wire like in the instructions. I went ahead and did so like in the instructions and it seemed to react and added tons of power but also triggered a check engine light. What purpose does grounding it serve? How do I get rid of the check engine?