I have a 94 civic with a d16z6. About 2 weeks ago my car started sputtering while accelerating. I figured I needed a tune-up so I went ahead and changed the oil,spark plugs,and spark plug wires. After the tune up nothing changed, then about a week later the CEL turned on, code 45 (3 slow flashes following 1short flash) which is fuel too lean or rich but the CEL turnes on at any random time and if I turn the key off it goeso away. I started searching and most threads said it was the.O2 sensor so I went ahead and changed it but had no luck. I also cleaned out my injectors but also with no luck the problem is still there. Any ideas as to what else can be wrong or how to fix the problem? Thanks

 

part of the tune up is to replace rotor and cap. use OEM only!

 

How is 3 long flashes and 1 short flash code 45? I'm lost.

What type of O2 sensor did you change? Civic is very picky about those things. Also, like EsotericImage said, replace rotor and cap also. Then check the timing.

 

Think your 3 long 1 short is code 31.

Check for air leaks. A crack in your exhaust manifold can cause things like this. If your getting outside air in there, your o2 sensor will be off, and your ecu will start throwing the wrong amount of fuel.

 

A 94 Civic does not have a code 45. Post a video of the blinking CEL.

The CEL may have blinked 4 long and 1 short, which is code 41. This would be a circuit problem for the heater element of the O2 sensor.

As Esoteric mentioned, also do a full ignition system tune up, a well as replace the fuel filter.