My teenage son's 1999 E320 wagon blew the driver side diverter valve off its mount due to a missing mounting screw and the subsequent damage of exhaust gasses has melted the wiring harness carrier and burnt back some insulation on the #4 cyclinder fuel injector elect. connector. I made a steel plate and gasket to cover the missing diverter valve, but now the entire bank of cylinders 4, 5, and 6, are throwing OBD misfire codes and shut the engine down when throttling up to 2000 rpm or greater.

The car appears to run fine at idle without misfire until I throttle up. I did get a misfire when shaking the wiring harness. I have plugged the vacuum line where it would have joined the diverter diaphram. The vacuum hoses are probably in need of replacing. The car ran fine before the diverter broke and the heat damage.

Where do I begin? I just found the replacement part on PartsGeek for $165, but I want to be sure that this will solve the problem before throwing money at the car.