c32used

Ok.............AMG Jerry was checking the diagnostics in the car and he clicked on the ECU and it had a code 16 on it now its not a warning. He said based of reading the other numbers that the ECU was modified possibly in jan,feb or march 2006 but I bought car in ending on June or July. I know theses cars are not posi but I notice that when I do a break torque that both wheels spin leaving a patch. AMG Jerry told me to try to do a donut but I said I will wait til snow to see. By trying the donut the car should not pass about 90 degrees in a turn without posi. I have the service work from MB and no modification shown here for ECU or poossible LSD. Is there a way for me to check 2 see who modified the ECU? I also spoke with a mechanic and he states that 16 is not used by MB for ECU. I am confused. I am thinking that previous owner modded the car some what how can I find info on previous owner? The car had K&N filters on it and AMG Jerry said the pulleys appear stock but he could of taken them off and sold them.