Misfire Cylinder #3
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Misfire Cylinder #3
I have a 2002 Honda Civic LX Manual w/ 235k Miles.
A couple of weeks ago my car started misfiring, I have a Scan Gauge and and read the code P0303 (Misfire Cylinder #3). Luckily I had a socket set on me and I was able to remove the Ignition Coil, I noticed there was oil in the spark plug chamber leaking past the spark plug seal. I cleaned both the spark plug and inside the Coil as best I could, then swapped coils around and I was on my way.
Last weekend I was able to replace the valve cover gaskets, spark plug gaskets/seals, and for good measure while I was inside there did a valve lash adjustment. I also replaced all the ignition coils, cleaned all the connectors with QD electronic cleaner. I inspected all the spark plugs and they all look great, they all have been replaced about 10k miles ago with OEM NGKs. Also for good measure I decided to SeaFoam the car.
For a couple of days my car ran great, just like when then car was new, more power everywhere in all RPM ranges, smoother and less noise. Probably due to the valve lash adjustment, I was very happy with the engine, it felt like the engine instantly gained 15HP.
Until three days ago..... I started getting the P0303 code again. At idle the engine will misfire and and my CEL will blink (P0303). Sometimes you can press the gas a little to get the RPMS to 2k and the Misfire will go away for a bit then come back. If you try to drive the car, codes P0300, P0301, P0303, and P0304 will show up on the Scan Gauage. Notice P0302 is absent, weird... I guess the misfire in Cylinder #3 is causing the engine to go "unbalanced" and causing the rest of the misfire codes to show up? The 4 codes (P0300, P0301, P0303, and P0304) will only show up during a drive though not at idle, at idle only code P0303 will show up. For a while it will only misfire after you driven the car for more than 20 minutes, when you start the car cold it wont misfire. This morning though it started misfiring #3 from a cold start.
I check my radiator fluid levels and they look good, I replace my Head Gasket about 20k Miles ago with a new OEM one. I don't think it is a the spark plug, they are relatively new and I don't think I put them back in the same order I took them out. Ignition coils are new.
I am not sure where to look next, Fuel injector, Fuel Pump, EGR? Any direction is much appreciated!
A couple of weeks ago my car started misfiring, I have a Scan Gauge and and read the code P0303 (Misfire Cylinder #3). Luckily I had a socket set on me and I was able to remove the Ignition Coil, I noticed there was oil in the spark plug chamber leaking past the spark plug seal. I cleaned both the spark plug and inside the Coil as best I could, then swapped coils around and I was on my way.
Last weekend I was able to replace the valve cover gaskets, spark plug gaskets/seals, and for good measure while I was inside there did a valve lash adjustment. I also replaced all the ignition coils, cleaned all the connectors with QD electronic cleaner. I inspected all the spark plugs and they all look great, they all have been replaced about 10k miles ago with OEM NGKs. Also for good measure I decided to SeaFoam the car.
For a couple of days my car ran great, just like when then car was new, more power everywhere in all RPM ranges, smoother and less noise. Probably due to the valve lash adjustment, I was very happy with the engine, it felt like the engine instantly gained 15HP.
Until three days ago..... I started getting the P0303 code again. At idle the engine will misfire and and my CEL will blink (P0303). Sometimes you can press the gas a little to get the RPMS to 2k and the Misfire will go away for a bit then come back. If you try to drive the car, codes P0300, P0301, P0303, and P0304 will show up on the Scan Gauage. Notice P0302 is absent, weird... I guess the misfire in Cylinder #3 is causing the engine to go "unbalanced" and causing the rest of the misfire codes to show up? The 4 codes (P0300, P0301, P0303, and P0304) will only show up during a drive though not at idle, at idle only code P0303 will show up. For a while it will only misfire after you driven the car for more than 20 minutes, when you start the car cold it wont misfire. This morning though it started misfiring #3 from a cold start.
I check my radiator fluid levels and they look good, I replace my Head Gasket about 20k Miles ago with a new OEM one. I don't think it is a the spark plug, they are relatively new and I don't think I put them back in the same order I took them out. Ignition coils are new.
I am not sure where to look next, Fuel injector, Fuel Pump, EGR? Any direction is much appreciated!
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I'm confused at this point. Sounds like you still have misfire issues, yes? You just resolved the oil leak problem.
I would double check all the connections on the coils, clean all the plugs, make sure you use dielectric grease on all the connections etc. cleaning the EGR valve can't hurt although typically that seems like a cause of stalling or poor fuel economy rather than a misfire - but if you have a dirty EGR that is causing a sensor to read incorrectly, that could cause an issue with your fuel mixture I suppose. One would think you would be tripping a code for that, but I've seen that happen before.
You could also test your fuel pressure while you're at it, just to help narrow things down.
I would think if the crank sensor was faulty you'd tripp a code for that also, but if it's not functioning properly that could cause a backfire.
I would double check all the connections on the coils, clean all the plugs, make sure you use dielectric grease on all the connections etc. cleaning the EGR valve can't hurt although typically that seems like a cause of stalling or poor fuel economy rather than a misfire - but if you have a dirty EGR that is causing a sensor to read incorrectly, that could cause an issue with your fuel mixture I suppose. One would think you would be tripping a code for that, but I've seen that happen before.
You could also test your fuel pressure while you're at it, just to help narrow things down.
I would think if the crank sensor was faulty you'd tripp a code for that also, but if it's not functioning properly that could cause a backfire.
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I'm confused at this point. Sounds like you still have misfire issues, yes? You just resolved the oil leak problem.
I would double check all the connections on the coils, clean all the plugs, make sure you use dielectric grease on all the connections etc. cleaning the EGR valve can't hurt although typically that seems like a cause of stalling or poor fuel economy rather than a misfire - but if you have a dirty EGR that is causing a sensor to read incorrectly, that could cause an issue with your fuel mixture I suppose. One would think you would be tripping a code for that, but I've seen that happen before.
You could also test your fuel pressure while you're at it, just to help narrow things down.
I would think if the crank sensor was faulty you'd tripp a code for that also, but if it's not functioning properly that could cause a backfire.
I would double check all the connections on the coils, clean all the plugs, make sure you use dielectric grease on all the connections etc. cleaning the EGR valve can't hurt although typically that seems like a cause of stalling or poor fuel economy rather than a misfire - but if you have a dirty EGR that is causing a sensor to read incorrectly, that could cause an issue with your fuel mixture I suppose. One would think you would be tripping a code for that, but I've seen that happen before.
You could also test your fuel pressure while you're at it, just to help narrow things down.
I would think if the crank sensor was faulty you'd tripp a code for that also, but if it's not functioning properly that could cause a backfire.
I have new Coils, and while the spark plugs were out I cleaned them, so I don't think it's a bad connection, I'll take the spark plugs out again and do your dielectric grease idea while I am in there.
I guess next step for me is checking the EGR valve.....
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Update:
2 weeks ago I started removing parts to get to the fuel injector base to clean the EGR passages. The passages were clean..... After some research I found my year Civic does not have a EGR valve so that explains the clean passages. I reassembled everything and installed new Fuel Injector Base Gasket, Intake Manifold Gaskets, Throttle Body Gasket and both Upper and Lower Fuel Injector Rings.
The Civic has been running fine now for 2 weeks, no misfires.......
I don't have a definitive answer on what fixed the issue, but my best guess is there was a air leak on one of those gaskets causing the cylinder to run to lean and misfire....
2 weeks ago I started removing parts to get to the fuel injector base to clean the EGR passages. The passages were clean..... After some research I found my year Civic does not have a EGR valve so that explains the clean passages. I reassembled everything and installed new Fuel Injector Base Gasket, Intake Manifold Gaskets, Throttle Body Gasket and both Upper and Lower Fuel Injector Rings.
The Civic has been running fine now for 2 weeks, no misfires.......
I don't have a definitive answer on what fixed the issue, but my best guess is there was a air leak on one of those gaskets causing the cylinder to run to lean and misfire....
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From: Paradise Ca
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Update:
2 weeks ago I started removing parts to get to the fuel injector base to clean the EGR passages. The passages were clean..... After some research I found my year Civic does not have a EGR valve so that explains the clean passages. I reassembled everything and installed new Fuel Injector Base Gasket, Intake Manifold Gaskets, Throttle Body Gasket and both Upper and Lower Fuel Injector Rings.
The Civic has been running fine now for 2 weeks, no misfires.......
I don't have a definitive answer on what fixed the issue, but my best guess is there was a air leak on one of those gaskets causing the cylinder to run to lean and misfire....
2 weeks ago I started removing parts to get to the fuel injector base to clean the EGR passages. The passages were clean..... After some research I found my year Civic does not have a EGR valve so that explains the clean passages. I reassembled everything and installed new Fuel Injector Base Gasket, Intake Manifold Gaskets, Throttle Body Gasket and both Upper and Lower Fuel Injector Rings.
The Civic has been running fine now for 2 weeks, no misfires.......
I don't have a definitive answer on what fixed the issue, but my best guess is there was a air leak on one of those gaskets causing the cylinder to run to lean and misfire....
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Im going through the same thing. Misfire in cylinder 3 changed the coils and the car runs smooth but a few days later my car still jerks at high speeds. MY sparkplugs are fairly new with only 16k on them. Did you manage to pinpoint what was causing this issue?
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I could not pinpoint the issue, what I do know is that when I changed out all the Gaskets and O rings it stopped....
My local Advanced Auto parts sold a gasket kit that contained all the gaskets related to the air intake system, the metal fuel injector base gasket that goes between it and the block, the intake manifold gaskets, and the throttle body gasket. Then I purchased the upper and lower fuel injector O rings and replaced them. While my fuel injectors were out I cleaned them with carb cleaner.
My local Advanced Auto parts sold a gasket kit that contained all the gaskets related to the air intake system, the metal fuel injector base gasket that goes between it and the block, the intake manifold gaskets, and the throttle body gasket. Then I purchased the upper and lower fuel injector O rings and replaced them. While my fuel injectors were out I cleaned them with carb cleaner.
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