2001 S8

Hey D2 Owners,

I'm planning to change my D2 spark plugs in a month or so. This job looks pretty easy so I'll be tackling it myself.

My D2 is a 2001 with 96,500 miles on it. I have no Check Engine Light (CEL) on or signs of a bad spark plug. (rough idle or acceleration hesitation) However there are no records of the spark plugs ever being changed, so I'm doing this simply for peace-of-mind.

When I change out the spark plugs, should I also change all 8 ignition coils? Also should I go with Bosch 7406, Bosch Platinum +4 4457 or is there a different brand that will work?

S8ilver

You can't use the 4457 due to the tapered seat. You can use the 4417 or the 7406. Based on the thread below, I'm running the 4417 and have had no issues.

https://www.audiworld.com/forums/sho...ht=4417&page=2

I wouldn't change the coils. They tend to either work or not work. Perhaps carry a spare in the car so you could change on the side of the road if one went bad, but I wouldn't touch them now.

Also, while you have the plugs out, inspect for any oil in the plug tubes. Mine had oil in in a couple tubes at <70k miles. It's not a major thing, just means valve cover gaskets are due for a change.

dreamhope

I just did it this afternoon with Bosch Iridium 0 242 240 656. The old ones were OEM copper.

2001 S8

Thanks for the correction S8ilver and suggestions everyone. I'll probably stick with what is recommended: Bosch 7406.

Is there anything I would watch out for while doing the job besides oil in the tubes?

Thanks for chiming in : )

silverd2

I've used both the 4417 and 7406...comes down to driver preference. My observation, as is common with hotter or cooler burning plugs, the 7406 have a little more umph off the line, but slightly higher vibration at high rpm...the 4417 (platinum core burns cooler) is a little softer off the line, but ultra smooth and powerful at high rpms. I personally like the 4417's in my car.

Others swear by NGK single prong iridiums...I've never used em...they say there is noticeable more umph off the line over OEM, but I'm just guessing that's at the expense of smooth running at higher rpms (just a guess though).

2001 S8

Based on the info by silverd2, I think Bosch 4417 would be more what I'm looking for; a smoother ride.

Is there anything I need to do after changing the plugs or will the car adjust to the new plugs automatically?

silverd2

Plug-n-play...nothing else needed.

But speaking of "smooth"...I changed my front 02 sensors at a little over 100K miles and what a difference. They adjust the fuel mixture trim (rears do nothing except monitor and trip codes). Even without any 02 sensor codes, they are pretty much shot (inaccurate) at 100K miles +.

Something to think about in the not too distant future.

Let us know what you think about the feel of the platinum plugs.

twentysevenlitres

I've got NGK single-prong iridiums ready to go in at the next service (happening shortly).
I'll report back on any improvement/deterioration of engine smoothness and performance.

I'm pretty used to the performance of mine by now - which funnily enough is a bit rough at high rpm with a bit of pinging. Could be fuel related, I run 95RON real fuel - what did we decide that was equivalent to in the US in that fuel thread, 89, or 91 or something? 95 here is regarded as premium, but is one step below the better premiums such as BP Ultimate, Shell Optimax, Mobil Synergy 8000 etc, which are generally 98RON... Anyway, that's off-topic and an issue for another time!

2001 S8

Hey D2 Owners,

Update on the project: Finished the spark plug job today. The job took me about 2 1/2 hours to complete but I took my time and was very methodical during the process. The first and fifth cylinder plugs were in pretty tight. It took about 40 pounds of pressure to get them out.

I replaced the plugs with Bosch 4417. I figured by doing the job myself, I saved around $200.00.

All plugs were pretty dirty. See attached photos. They are not the sharpest photos but it is easy to see the plugs were about done.

After the job I took the car for a 30-mile drive (city roads & Interstate) much smoother!

Thanks for the recommendations everybody.