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All 8 Cylinders Misfiring

 
Old 04-02-2019, 01:59 AM
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Default All 8 Cylinders Misfiring

So I had decided to check my spark plugs a few weeks ago and realized that they were all the original ones from 2001. I ordered 8 more from FCPEuro and turns out that they gave me the wrong ones. I had put all 8 in and started the car to have all 8 cylinders misfiring on me. I emailed the company to find out that they were the wrong ones even though the website told me they were for my car. Anyway, I decided to put the old ones back in today and wait for my new set of 8 only to have all 8 cylinders misfiring when I put them back in. It was snowing and a few of them may have gotten some moisture on them when I was putting them into my block. I am not sure if that is the cause of it though. The car ran fine before I replaced them and not it's like sitting in a 3500 Ram and it's rocking the whole car back and forth. I decided to try and drive around the block and see if maybe the moisture would evaporate when it heated up and had no misfires while the car was moving. As soon as I had parked the car the CEL started flashing and I plugged my scanner back in and I had all of the misfires on there. From P0300-P0308. Any suggestions? I need this car running so that I can get to work tomorrow. This is a 2001 A8 L 4.2L V8.
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Old 04-02-2019, 04:07 AM
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What plugs are you trying to use?

Some say you must use the OEM-style plugs but I have been OK using something compatible, single prong double platinum if I recall. Gapped correctly of course.
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Old 04-02-2019, 06:01 AM
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I'd unplug the battery for 30 min and re-connect everything and see if that helps with the codes...

The coils might be giving you some grief too...

I wish I had a better advice to throw towards you...
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Old 04-02-2019, 07:23 AM
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Oh, so you get misfiring on the old plugs? You may have damaged (cracked) some coil boots if you did not disconnect the coils and pull them out straight up and carefully.
Codes should tell you which ones. They can be taped up in an emergency pending replacement.
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Old 04-02-2019, 10:22 AM
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Originally Posted by SC_09iduA View Post
I'd unplug the battery for 30 min and re-connect everything and see if that helps with the codes...

The coils might be giving you some grief too...

I wish I had a better advice to throw towards you...
I'm going to try the battery thing quick. You're the second person to tell me to try this.
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Old 04-02-2019, 10:25 AM
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Originally Posted by jfrahm View Post
Oh, so you get misfiring on the old plugs? You may have damaged (cracked) some coil boots if you did not disconnect the coils and pull them out straight up and carefully.
Codes should tell you which ones. They can be taped up in an emergency pending replacement.
How would i know if they broke? I get codes for all 8 cylinders. None of them were hard to pull off. They just slide out without much effort.
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Old 04-03-2019, 05:27 AM
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Any luck on the battery disconnect/re-connect?! If you have anyway of checking resistance and power on the coils, perhaps that's another area to concern...many heat cycles causes these coils to fail without warning...granted, the CEL generally aligns one to where and what is going on...Hmmm, Sounds like an electrical gremlin is in our midst!
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Old 04-03-2019, 03:05 PM
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UPDATE:
Today I did an Ignition Coil inspection, put dielectric grease on the plug tips, torqued down the spark plugs to 22 Ft. Lbs., and listened for vacuum leaks. The car does run smoother it seems but I still have at least 4 misfires happening. There is a vacuum leak behind the motor near the blower motor but I could not pinpoint it.
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Old 04-03-2019, 03:08 PM
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Originally Posted by SC_09iduA View Post
Any luck on the battery disconnect/re-connect?! If you have anyway of checking resistance and power on the coils, perhaps that's another area to concern...many heat cycles causes these coils to fail without warning...granted, the CEL generally aligns one to where and what is going on...Hmmm, Sounds like an electrical gremlin is in our midst!
That did not fix it. Coils looked fine and I am starting to think that its not a spark issue but an air issue. Car is running pretty rich.
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Old 04-04-2019, 04:18 PM
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I just found my vacuum leak and its pretty big. It was there before but i think it may be my issue. I sprayed carb cleaner on it and it rev'd up nice and was stable for a few seconds. Going to replace it if i can find one and the I should be ok. Ive got a video where you can hear it if anyone is interested. I was using it as a flashlight while recording so its pretty shaky but you can hear everything.
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