I recently swapped an OBD1 B18C into my 98 Civic EX. I'm using my EX engine harness. I had a problem with the speed sensor that was on the B18C. The speedo read on zero at any speed. So I swapped it with the EK's speed sensor. Well it worked just fine. The speedo read just fine after that. Now it is messed up again. The speedo reads either on 20 mph or 30 mph at highway speeds. When I slow down to come to a stop...it bounces up and down like crazy. I unplugged the sensor to see if the speedo would go back to zero...but it didn't. So please someone help me with this problem. Is it the speed sensor or the speedo?