98 Civic Ex misfire mania - any suggestions?
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98 Civic Ex misfire mania - any suggestions?
I have a 98 Civic EX with over 240000 miles on it.
It has an cylinder 3 misfire for over a year now. About two months ago we changed plugs, wires, distributor cap and rotor, fuel injector #3, new fuel pump, and ignition coil (timing belt was put on about 3 years ago) My buddy did a "ghetto" timing belt test and did a "ghetto" cylinder test. I'm not a car whiz. He had me try to crank the car with the spark plugs out. That is what I mean by "ghetto test" I don't remember how he checked the timing belt without removing any parts, but he said he did. We put on a new fuel filter about four years ago. Not throwing my buddy under the bus. He went to automotive school for what it's worth and has done fantastic (super affordable) work on my car for nearly a decade. This is the first time he has not been able to solve a problem.
The misfire comes and goes all day. Sometimes the check engine light goes out for a couple of days. The car runs smoothly for maybe 30 minutes, then it starts misfiring. Then it's smooth again. It goes back and forth all day, runs pretty smooth on the highway 70% of the time but almost always misfires going up hills on the highway. And then the check engine light comes on again with the cylinder 3 misfire code. A few days later the light goes back off. All of this happens over and over.
I know my catalytic converter is pretty much toast. I used to get a catalyst deficiency code and O2 sensor code that started years ago, but since we stopped testing emissions here, I did not get a new cat. The codes for the cat hardly ever come up anymore for some reason.
The one thing I have not changed is the distributor itself. (I think) Seems like we have changed everything, but I guess only the cap and rotor were changed. The rotor looked pretty bad if I recall.
I don't know if it's relevant but all of this started after we had a very bad freeze here in the south winter of 2023. It almost never gets that cold where I am at. Everything was frozen. After that the car was never the same. Before the freeze it ran perfectly. A couple of days after the freeze it wouldn't start at all. My buddy finally got it going and it was instantly misfiring and has never stopped since that day. He did the plugs, wires, cap and rotor back then also. At one point a week later it misfired so horribly I could barely get it home. It has never misfired that bad again but we can't get it to stop.
We tried someone's recommendation about checking some fuses, but my diagram didn't seem to match up with what a guy on here said about the same model car. My buddy didn't find anything wrong looking with the fuses that he did check.
I wouldn't think that a bad cat would make the same 3 cylinder misfire and no other ones. Seems like the problem would be widespread.
It has an cylinder 3 misfire for over a year now. About two months ago we changed plugs, wires, distributor cap and rotor, fuel injector #3, new fuel pump, and ignition coil (timing belt was put on about 3 years ago) My buddy did a "ghetto" timing belt test and did a "ghetto" cylinder test. I'm not a car whiz. He had me try to crank the car with the spark plugs out. That is what I mean by "ghetto test" I don't remember how he checked the timing belt without removing any parts, but he said he did. We put on a new fuel filter about four years ago. Not throwing my buddy under the bus. He went to automotive school for what it's worth and has done fantastic (super affordable) work on my car for nearly a decade. This is the first time he has not been able to solve a problem.
The misfire comes and goes all day. Sometimes the check engine light goes out for a couple of days. The car runs smoothly for maybe 30 minutes, then it starts misfiring. Then it's smooth again. It goes back and forth all day, runs pretty smooth on the highway 70% of the time but almost always misfires going up hills on the highway. And then the check engine light comes on again with the cylinder 3 misfire code. A few days later the light goes back off. All of this happens over and over.
I know my catalytic converter is pretty much toast. I used to get a catalyst deficiency code and O2 sensor code that started years ago, but since we stopped testing emissions here, I did not get a new cat. The codes for the cat hardly ever come up anymore for some reason.
The one thing I have not changed is the distributor itself. (I think) Seems like we have changed everything, but I guess only the cap and rotor were changed. The rotor looked pretty bad if I recall.
I don't know if it's relevant but all of this started after we had a very bad freeze here in the south winter of 2023. It almost never gets that cold where I am at. Everything was frozen. After that the car was never the same. Before the freeze it ran perfectly. A couple of days after the freeze it wouldn't start at all. My buddy finally got it going and it was instantly misfiring and has never stopped since that day. He did the plugs, wires, cap and rotor back then also. At one point a week later it misfired so horribly I could barely get it home. It has never misfired that bad again but we can't get it to stop.
We tried someone's recommendation about checking some fuses, but my diagram didn't seem to match up with what a guy on here said about the same model car. My buddy didn't find anything wrong looking with the fuses that he did check.
I wouldn't think that a bad cat would make the same 3 cylinder misfire and no other ones. Seems like the problem would be widespread.
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