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This is my first car so I'm still learning a lot and how to do things so I could use all the help I can get.
I have a 2003 Honda Civic EX 1.7L standard with about 140k miles. Fantastic car no problems until recently. Several hours into a move I got the check engine light and it said it was misfiring on all 4 cylinders (P0300-P0304). No other indications of a problem before hand.
Tried a few easy fixes with no luck. I then changed the fuel pump and when I went to start it, it didn't start. I changed the spark plugs and it started and the light cleared immediately.
Long story short I think the fuel filter might have been clogged from a gallon I had drained from a motorcycle.
I made it to where I was going, drove it quite a lot while there and had no problems for 2 months. Got an inspection from a mechanic shop and they said it was in great shape.
Two months later I'm in the same situation, car loaded for a move several hours into a drive and the check engine light came back on. Same codes (P0300-P0304).
I'm still suspicious of the fuel pump/filter because it's after market. I'm thinking I'm going to try a fuel pump test kit to see if it's at the right pressure and possibly try cleaning the fuel tank.
Beyond that I'm short ideas of what to do. I have only a few days before I have to be back on the road for several days so if I can't get this sorted I'm worried I'll have to finish the drive with it misfiring and possibly breakdown fully or have to replace the car mid way through this drive.
Any suggestions or advice would be greatly appreciated! Thanks for reading!
Clogged EGR runners in the intake manifold can cause misfires on all cylinders. It's also fairly common. Does your engine have EGR? I have to ask because some do and some do not. The thing circled in red below is the EGR valve.
Clogged EGR runners in the intake manifold can cause misfires on all cylinders. It's also fairly common. Does your engine have EGR? I have to ask because some do and some do not. The thing circled in red below is the EGR valve.
I checked the fuel pump pressure, compression ratios of the 4 cylinders, cleaned the EGR valve and the fuel injectors. I made it another several days and about 500 miles and the light came back on.
I don't really understand what could cause the code to throw hours into drives but not on shorter drives?
05-08-2023
