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Old 06-15-2018, 11:54 AM   #1
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Consistent misfire on Cylinder 5 causes?

I have a 99 base USA spec car. I have had the car 5 years. I probably put 1500 miles on per year. I am getting a consistent misfire on cylinder 5. Consistent being the last 2 days. Last year I replaced the coil packs with with BERU upgraded mounting units. About 3-4 years ago I replaced the spark plugs and tubes. I am not sure I think I used NGK plugs. I change the oil and replace air filter every spring. What could be causing the misfire? I ordered another coil pack and was going to replace the #5 spark plug just to be on the safe side. I am thinking it might be the wiring to the coil pack. I found plug with wiring for $35. Anyone have any ideas what it could be? besides coil, plug, wiring?

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Old 06-15-2018, 12:46 PM   #2
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do you have an aftermarket intake or have you done work in that area of the engine? the wiring to the #5 fuel injector is exposed to damage where it plugs into the injector.
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Old 06-15-2018, 01:30 PM   #3
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Intake is stock. Last winter I did a complete suspension overhaul. That is most recent work. I might swap coilpack with #4 and replace spark plug to see if that makes a difference
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Old 06-15-2018, 02:06 PM   #4
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Swapping the plug and coil is a good easy test. A compression check will help eliminate (or suggest) some possibilities. Compression testers are cheap and not too hard to do the check. Possibly the injector on 5. I've never had a bad injector, but i expect it can be swapped with another cylinder to check if you don't want to take them all to a shop.
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Old 06-15-2018, 02:26 PM   #5
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I’d swap coil packs to see if the misfire follows. If not, do the same with plugs, then injectors.
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Old 06-17-2018, 06:05 AM   #6
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I swapped coilpack on cyl 4 & 5 and went for a long ride. No misfire so I am thinking the plug was loose on cyl 5. Hopefully non issue!

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