I just picked up my '02 P5 yesterday and was making a mental list of what it needs and what I need to do to it. It has 142,000 miles on it.
First is a new battery as it turns a little slow and the guy I got it from said it's been sitting about five months.
Second would be a tune up: plugs, wires, filters.
Now here is my question: should I replace the coils? How do I tell whether or not they need to be replaced?
Watching utube, I gotta say I don't remember seeing an easier engine to work on... ever!

Let's change #1 to clean, clean, clean it up.

 

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Technically speaking the actual only way to fully check a coils operation and performance is to use an oscilloscope and run up the engine and examine the results. This is generally done with someone trained and experienced in using an oscilloscope for engine and ignition diagnosis.
Otherwise the common sence inspection for overall condition looking specifically at deterioration of soft components and any rust or oxidization on the many parts of a coil that can lead to continuity problems. Also inspect the electrical connector for the same.

 

Since I posted this question I wondered if Google might of had an answer.
Here is what I found:
So your answer makes sense and the mileage thing also makes sense.
I'm at 142K so I really doubt they've been changed.
Guess I'll add those to the list. (along with the new wires of course)

 

Information on the internet is not always accurate regarding what any Automotive parts longevity is and like a large amount of internet information is simply copied and passed on until that phenomenon happens it becomes a weird FACT! .
I work with and have close friends that are Drive-Train Engineers for a few leading auto manufactures and we always get a kick out of what the internet says about parts and how things are perceived developed.

I simply ask who ever did the tests on parts to determine them lastly more then 10 years or 100k miles. hehehehe!

How can anyone or any company possibly cover all the conditions ITRW (in the real world) that can effect any giving part and how long they will last? That's is why there are break downs of the automotive warranty on what is covered. At one time in the industry it was one number of miles and years now it is many.

 

OK, I'll give you that.
I really don't want to spend a lot of money on diagnosing coil packs when it's probably cheaper to throw some new ones in.
At least then it's done and out of the way.

 

Unless they have visual wear or you have a DTC relating to possible coil problem, I would first recomend to do a simple electronic tune up spark plugs and spark plug wires. Changing coil more often then many realize creates problems that were not originally there. Really there are no moving parts on a coil, fluid to keep the transformer portion cool are all but gone in the industry, they are not exposed to all the extreme exposed environment , its not a Turbochraged engine and the coil s are not so close to unprotected heat radiation that the soft components will deteriorate with any predictability then why change them unless you simply want the peace of mind having a new part? As you have already noted your engine is very easy to work on so changing them when there is a real problem seems more logical?

I can't tell you how many customers over the years bring their vehicles to me after a DIY tune up that a problem was created or one not solved and they threw a bunch or parts on it with out regards to a proper way of diagnosis parts condition only to make more problems and paying me to fix it. hehehehe!

 

Damnit. Stop making sense.
Well, it will save some coin upfront.
Thanks for the advice.

 

Don't forget the battery condoms....those are the anti corrosion washers they always try to add on sell you but really they work. I would also recomend when you purchase the battery to have them load check it before you leave the store. You would be surprised how many batteries are not up to "new" condition!
You are in WA so I suspect you are going to Auto-zone or the other chain store? If you get cheap and go to COSTCO be careful because most do not have a way to load test batteries? Auto-zone can also check your charging system which is important to all operating aspect of your new ride!
This is a new vehicle to you so I would do an engine oil and oil filter change for a baseline start of your work.

Then do the complete visual check from bumper to bumper of the suspension and overall areas for wear of parts or damage that is not usually seen from casual up-keeping.

 

I didn't mention the oil change because that's a given.
I also don't consider Costco a cheap way out. They sell Interstate batteries for really good prices and I've had excellent luck with them. Those battery doughnuts are great. Use them on everything I have. Planning on buying the battery and testing at home before putting it in the car. I have a load tester & charger.
In the glove box was the original owners manual and stuff that comes in the black zippered case. I saw it came with factory wheel locks and the registration papers from Mazda in with the manual. I noticed the locks on the wheels but wasn't thinking at the time. Now a little worried about the key. Gotta check the lug wrench. I think that's what the manual said where it was.

 

Sorry I should have said inexpensive and not used the word "*cheap" (*as in inexpensive)

Interstate is a good battery overall but still now made from recycled battery materials.This is a common practice now and less battery manufactures use all new material as one example Optima only uses 99% pure virgin lead. ( I do not know about the plastic part of them but plastic does not wear out or decompose on an automotive battery that I am aware of). Interstate do have a nation wide coverage and are very good with customer service..
I use to be a Intestate dealer , sold hundreds of them and also warrantied many. If you get one from Costco look for the manufactured date of the battery and not the little tag placed on the battery. You can learn how to read the actual date that is melted in the top box edge of the battery on the internet. To much for me to type. Most all retailer will rotate old new stock and test then place a new date tag on the the battery. This is also common practice done for decades. Normally there is nothing wrong with this practice nor is it considered unethical.

Glad to hear you have a "load Tester" as a DIY. You would be surprised how many work on their own cars and don't have some of the simple and needed tools and diagnostic equipment to keep their vehicles running well and out of service shops. HA!