Hey all, I have an 87 GMC Jimmy fullsize. I put a pace performance crate motor in it and it is running fine except for one thing. When I towing my boat or getting on it a bit the valve train will rattle a little and the check engine light comes on. Well that is the it rattles a little and then it seems like the knock senor reads it then retards the timing and the rattle stops. About 2 seconds later the check enging light comes on. After shutting the motor off and restarting the light is out and it seems fine. When I installed the motor I put a new knock sensor in and disconnect the brown timing wire before I timed the motor. Anyone have any ideas on this? The ECM code is 43 which is knock sencor. I check the wire and it is still pluged in. Thanks!