I recently brought a 1994 mondeo 2.0, 16v 136 PS whose head gasket hd gone. I removed the head which I had skimmed and replaced the head gasket. When I attempted to start the engine I had a misfire. I checked the voltage at the inector solenoids, all had 11v except for cylinder 4. which had no voltage. I followed the cable back to the ECU and there was no voltage on the output pin from the ECU. replaced ECU same fault. Please help.