All 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 now 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.

I know this means it is an Audi A8. Not all posters would know that. How many miles on the car?

It isn’t clear from the post… The car was NOT misfiring before you change the spark plug? Yes?

The misfiring started after installing the wrong plugs? Right?

Then you re-installed the original plugs and the car is still misfiring? Right?

If I read that right, I suspect you damaged a plug or two removing them and the re-installing them. Installing new, correct plugs is the place to start.

There may be another problem that just coincidentally showed because you changed plugs. If the wrong plugs sent had a slightly shorter insulator side, the lack of contact with the coils may have burned the coil contacts to the plug. If that happened, all the coils need replacing. Also, carefully check the harness to the coils to make sure you plugged them in properly and they are fully seated. Then check back along the harness to where you bent it to lay it back out of the way for broken wires. You may have to unwrap the harness to find the problem.


You did read that correctly. Misfire started after new plugs and continues after putting the old ones back in. It was not misfiring before this. The car has 135k miles on it. Im working on getting the mew plugs but it may take a week or two to get them since they come from Europe and I have to send these back before getting my new ones. I will check to see if there is spark when I get home by pulling the wires and turning over the engine for each wire. I will also check to make sure they are seated correctly, I had a feeling that with how long the wires are going into the motor that maybe they are on right or are sitting on the side of the plug and not directly on it. Ill let you know what I find. It will be about 10 hours before I get home to check.

Who in the hell orders spark plugs over the Internet?

Let alone from Europe!?



I heard that local parts stores sell spark plugs , does this person live some place that does not have parts stores.

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I am not sure if it is coil on plug or standard spark plug cables, if not coil over plug I would suspect the cables, Now I am not an expert on your car and cables but some cables can be really sensitive and fail due to improper handling.

Could be wrong firing order. Did you replace the plugs one at a time?

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My local auto parts stores don’t sell Audi parts(not even spark plugs). The only other place is the dealer for $15-$20/plug.

I did them one at a time to keep that from happening.

I don’t think it’s coil over plug as i feel no resistance when putting the wires into their respective slots, they just sit in there.

Audi doesn’t make spark plugs

Bosch supplies Audi/VW their spark plugs.


What plugs? I think you want NGK 101000035HJ. If you clear codes and still get the misfire on all 8 cylinders, the problem is 99% sure not the plugs or the coils, and is most likely due to a disconnected hose (from the work) causing a vacuum leak.

Right but they don’t sell the spark plugs that i need at any of my local parts stores.

I originally bought Audi VW Spark Plug - Denso K20PBRS10, the ones that I need are Audi VW Bosch Spark Plug - Bosch 101905615A

I do. I rarely go to the brain dead guys at the local auto parts store unless I am stuck. Plus it is typically a fraction of the cost online for the same parts. If the parts store kid is younger then the age of your vehicle you are screwed and almost guaranteed multiple trips. Half the time they don’t stock what I am looking for and they say I can order it for you and it will be 2 days. Well if I gotta wait for them to be delivered then drive the 45 minutes each way to the parts store to pick them up, I might as well just order my parts online directly, save 50%, and get delivered to my house for no extra up charge.

I probably ordered about $4,000 in parts on RockAuto last year for my personal vehicles (That includes the parts to rebuild a V10) and ordered about 20 tires online as well for home delivery. The UPS man doesn’t like it when I order a set for the dually and 2 cars on the same order. 14 tires in a UPS truck basically filled up his truck and I live a long way down a dirt road.

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What do you do when you drop one of the new spark plugs on floor and it breaks?


Rockauto has your Bosch spark plugs for $4.34 each.,2001,a8,4.2l+v8,2617,ignition,spark+plug,7212

And you can cross-reference the part number here.


Literally, millions of people…at least over the internet. I used to have a Mazda Protégé that really favored the OEM NGK plugs; however, the local parts stores didn’t have the NGK plugs and I was 2+ hours from a dealer. So…internet.

First you curse very loudly, then you cry, and sob yourself to sleep thinking about the wait on that slow boat from Germany.


Thank you. I will order some later today.