Cylinder 8 misfire?
02-28-2012, 11:51 AM
#1
Staging Lane
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Cylinder 8 misfire? My 99z28 is throwing a cylinder 8 misfire code,I just got the car back from getting the trans rebuilt and my trans guy scanned for codes and the cylinder 8 misfire code showed up.It is barely noticeable and doesn't do this all the time,but when taking off from a complete stop,the car will hesitate a little during low rpms,other than that the car is driving good and shifting smooth through all gears.I did not check the plugs,wires,or coils yet,but i do have a set of ngk tr5 plugs that i will put in and see what happens.I know this isn't a big problem but it is ok to drive the car like this without hurting anything right?
02-28-2012, 06:46 PM
#2
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I believe #8 is all the way in the back of the engine I believe on the passenger side. Did you have plugs and/or wires installed recently or any work done to the rear of the engine? Your gonna have to check for yourself but I guarantee you that the plug wire is not seated all the way on the coil pack or the spark plug, one or the other. Pull the wire and check for corrosion and if everything looks ok put it back on. Very rarely do coil packs go bad but that could be the problem too and there's a continuity test you can do.
02-28-2012, 08:10 PM
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Staging Lane
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All plugs,wires,and coils never been changed since i.got the car a year and a half ago.Car is pretty much stock besides exhaust,lid,and underdrive pulley and no work was done to the engine or rear,i did just have the trans rebuilt but thats it.I will check the coils and plugs when i get time this weekend.
02-28-2012, 09:19 PM
#4
It depends how often the misfire is occurring, but the less you drive it, the better. Unburnt fuel is being expelled and can ruin your cats long term, or could even cause damage if it ignites in the exhaust causing a backfire. More likely are just some extra deposits in the area.
First course of action is to check the plugs. If #8 is missing an electrode or something serious like that, you'll know right away. Yeah, this is the plug that's farthest to the rear, which happens to be on the passenger side, and it's easiest to get to from underneath the car. Have a good collection of different size ratchet extensions to get at it and some fresh di-electric grease for the plug wire boots. If you have the time, I'd just replace all the plugs based on the vintage of your car. Have fun!
First course of action is to check the plugs. If #8 is missing an electrode or something serious like that, you'll know right away. Yeah, this is the plug that's farthest to the rear, which happens to be on the passenger side, and it's easiest to get to from underneath the car. Have a good collection of different size ratchet extensions to get at it and some fresh di-electric grease for the plug wire boots. If you have the time, I'd just replace all the plugs based on the vintage of your car. Have fun!
02-28-2012, 10:04 PM
#5
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Well the misfire is barely noticable and doesnt occur often,sometimes it will sort of hesitate when taking off from a stop but 95% of the time I dont experience any sign.of a misfire.It is my daily driver,I mainly use it to drive back and forth to work which is about 15 or so miles total.But this weekend i will replace all the plugs and see what happens,i may also replace the coils and wires also since I havent changed them since I got the car.Thanka for the replies though.
02-28-2012, 10:14 PM
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I hope its plugs and wires. I too had the infamous misfire code mine was #6 changed plugs, wires, checked coils, and vacuum and all was good. Shop told me I a may have a soft valve spring or bent push rod. Took to another shop and found 75% leak down in the cylinder 
tore down the engine I had a broke ring land. I'm currently waiting on a rotating assembly going to stroke mine to 383 
. I hope it is a simple fix.
tore down the engine I had a broke ring land. I'm currently waiting on a rotating assembly going to stroke mine to 383 . I hope it is a simple fix.
02-28-2012, 10:19 PM
#7
Unless the plug is broken I'd imagine the problem would be with the wire or the coil. What year's your car? A '99? I once had a fuel delivery issue and an EGR problem with my '97 and it caused misfire codes. Hopefully you'll be done with just the plug/wire change...
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02-28-2012, 10:56 PM
#8
Well the misfire is barely noticable and doesnt occur often,sometimes it will sort of hesitate when taking off from a stop but 95% of the time I dont experience any sign.of a misfire.It is my daily driver,I mainly use it to drive back and forth to work which is about 15 or so miles total.But this weekend i will replace all the plugs and see what happens,i may also replace the coils and wires also since I havent changed them since I got the car.Thanka for the replies though.
Make sure to keep all the plugs and put them aside in order in case you have other issues. Also, take pics of them, especially #8, and post. 
03-02-2013, 11:40 AM
#10
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I had a pin hole in one of my plug wires that was hardly noticeable and caused misfire issue. Inspect very closely, replace if need be. disconnecting the AIR tubes from manifold and taking the coil rails off the valve covers made it easiest for me to access all the plugs on both sides. Spark plug socket w swivel end, one add u joint, and two ext were only tools req.
