1998 Honda Civic random misfire
Hi,
I have a 1998 Honda Civic EX that has 125,000 miles on it. It started with a random misfire cylinder 1 code. We did a tune up: replaced spark plugs with NGK's, good spark plug wires, and replaced distributor cap and rotor. Car worked better for 2 days, then misfired on cylinder 1 and 2. We bought some Sea Foam and put in gas tank, thinking we had bought some bad gasoline. Worked good for about 2 days, then random misfire on all 4 cylinders and ignition module failure showed up when codes were read at Auto Zone. We replaced ignition module. Again, 2 days later, misfiring started. Went back to Auto Zone and got more Sea Foam. We unplugged the sensor by the throttle body and reattached it. Can has been running better since then. What else should we check? It had a 1399 error code but I don't remember the other codes. We had replaced the fuel filter also.