Rep Power: 0

Hey guys, hopping for some advice. I have 2001 Civic LX Manual (145k KM) that has gotten some misfire codes.

A month ago driving on the highway at cruise the car flashed the CEL a few times. No hesitation, no stuttering car was driving like normal. I check the code after the drive and had a P0302(Cyl 2 misfire) I cleared the code and put some injector cleaner and everything was great.

Fast forward to today and I was driving on the highway again at cruise and the CEL flashed again. Once again no stuttering no hesitation car drove normal. Check the codes again. This time had P0300(Random/Multiple Misfire) P0302 (Cyl 2 misfire) and P0304(Cyl 4 misfire).

The CEL never stays on and the codes are always stored as pending.

I replaced the spark plugs May of last year. I was thinking of swapping coils 1 and 2 plus swapping coils 3 and 4 to see if the missfires follow the coils.

Any suggestions would be great.

 
Rep Power: 209

You can try swapping coils but most likely not the issue. Try resetting the ECU by disconnecting the negative terminal from battery and turn the headlights on to discharge any residual voltage. After five minutes (headlights off) then reconnect negative terminal to battery. Start engine with all electronics (stereo, some light, etc..) off and let idle for 15 minutes. Hopefully, the code will not return.

You can check coils as shown in link: https://www.autopartswarehouse.com/b...t-a-coil-pack/

 
Rep Power: 228

For all 4 cylinders to fail at one time, I wouldn't be looking at single cylinder items (plugs, coils). I'd focus on what links to all four at once.

its probably not full related as far as delivery (lines, rail, pump, injectors)

I'd guess its signal related
-injector signal pulse interruption
-spark interruption

Could be a dying sensor
-MAP
-TDC
-Crank

But at this point you might want to wait for total failure, to locate the item, since only sensors from Honda are guaranteed to work.

 
Rep Power: 0

Thanks for the tips. I'll try to reset the ECU to see if it helps. If the CEL didn't flash I would have had no idea anything was going on. The car was at cruise under basically no load so not a common place to get knock.

If not I'll have to wait it out to see if any other codes come up.

 
Rep Power: 228

You can still scan for codes if the light isnt on.

There are pending codes, which dont keep the cel on.