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As I am writing this my car is at the mechanic , My 2005 Accord v.6 scanned for a Cylinder 5 misfire P305 error , replaced the destroyed plug, and ignition coil , but still get the flashing engine light. not running as rough prior to replacing parts , BUT the engine light is still flashing, and the scanner still coming up with the misfire Cylinder 5 P305 error code , now to back track , the spark plug hole was stripped , I had a family member use a spark plug re-thread kit to make new threads which enabled the new plug to be tightened , then put the new ignition coil on , and then test started the car , and as I said above still the same issue persisting .......what can this be ,

p.s. there's no significant loss of power ,
the engine is having some issue turning over with starting , but does . (there's a new battery I put in the car) just fyi .

I just hope this isn't major repairs
 

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The infamous spark plug ejection on cylinder 5. I would do a quick compression check on the engine. I suspect cylinder 5 will be much lower than the others. I would guess you have scored cylinder walls on cylinder 5.

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wow! "scored cylinder walls on cylinder 5" what does that mean ? also the compression check can find what? thanks for your comment reply ! :)

The infamous spark plug ejection on cylinder 5. I would do a quick compression check on the engine. I suspect cylinder 5 will be much lower than the others. I would guess you have scored cylinder walls on cylinder 5.

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and what do you mean "much lower then the others" sorry not familiar with the lingo lol
 

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The cylinder walls are where the pistons go up and down, and the rings on the Piston ride on the cylinder walls. Normally the cylinder is perfectly round and finished with a crosshatch pattern. That finish must be relatively free of gouges. When the spark plug is ejected from the cylinder the threads from the aluminum heads are pulled out with the spark plug. Some of the metal debris can go inside the cylinder and gouge the finish on the wall. If it is gouged the compression rings will not seal properly. That will cause low compression compared to the other cylinders. If there is a large difference in compression the engine will never run correctly and would give unequal power between the cylinders.

Compression is measured with a device called a compression tester. It is basically a pressure gauge, it measures the pressure in each cylinder. They should all be very close in the pressure they can generate so the engine runs smoothly. If the compression is lower on 5 then the others, that will set a misfire code. I hope that explains it.




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The cylinder walls are where the pistons go up and down, and the rings on the Piston ride on the cylinder walls. Normally the cylinder is perfectly round and finished with a crosshatch pattern. That finish must be relatively free of gouges. When the spark plug is ejected from the cylinder the threads from the aluminum heads are pulled out with the spark plug. Some of the metal debris can go inside the cylinder and gouge the finish on the wall. If it is gouged the compression rings will not seal properly. That will cause low compression compared to the other cylinders. If there is a large difference in compression the engine will never run correctly and would give unequal power between the cylinders.

Compression is measured with a device called a compression tester. It is basically a pressure gauge, it measures the pressure in each cylinder. They should all be very close in the pressure they can generate so the engine runs smoothly. If the compression is lower on 5 then the others, that will set a misfire code. I hope that explains it.




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thanks ! one thing that gives me hope is that there isn't a significant decrease in power . it's not hesitating either on acceleration .

I have 2 last questions Greg #1 do you think that the threads being stripped that it's definitely an ejection of the plug due to the all the things you detailed ?

and question #2 you know when disconnecting the plug on the ignition coil while idling you'll get that fluctuation in the idle (running like it will almost stall) until you reconnect it , so being said on the cylinder 5 that we replaced the plug & coil there is no difference in the idle either connected or disconnected what would that mean ?
 

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Question #1, 5 minutes with search will show you that cylinder #5 has had the issue of the spark plug loosening. It backs out enough that the pressure in the cylinder to push the sparkplug out of the engine, taking part of the threads with it. That is a well known issue.

Question #2 if there is no change disconnecting the wiring to the coil tells me that cylinder is not providing any power. The main reason is normally the coil is not sending current to the sparkplug. Another reason could be low or no compression.

I would make sure the sparkplug is firing, then check compression. One of those 2 test will fail.

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Question #1, 5 minutes with search will show you that cylinder #5 has had the issue of the spark plug loosening. It backs out enough that the pressure in the cylinder to push the sparkplug out of the engine, taking part of the threads with it. That is a well known issue.

Question #2 if there is no change disconnecting the wiring to the coil tells me that cylinder is not providing any power. The main reason is normally the coil is not sending current to the sparkplug. Another reason could be low or no compression.

I would make sure the sparkplug is firing, then check compression. One of those 2 test will fail.

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thanks again !
 

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Discussion Starter #8
The infamous spark plug ejection on cylinder 5. I would do a quick compression check on the engine. I suspect cylinder 5 will be much lower than the others. I would guess you have scored cylinder walls on cylinder 5.

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GREAT NEWS! My Mechanic said the spark plug/coil fix worked! he cleared out the flashing engine light, and test scanned again all the cylinders are at zero, I guess that means the same..... but HUGE crisis avoided! just gonna give it a full tune up , oil change , and maybe throw in a new starter, plus last night replaced the battery
 
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