on my 88 190e the oil level sensor is just above the oil drain plug on the pan. But looking through my performanceproducts mag, I dont see one listed for an 84 engine. so maybe the wire was never plugged in, if there is no where for it to go. The odometer may be jammed, as this is the case on my car. I havent gotten around to getting mine fixed or finding a replacement. And as for the temperature sensor, maybe the wiring differences between the harness from the 87 and the sensors on the 84 are not matched correctly, again this goes back to the oil level sensor issue. Hope this helps a little.