I have a 2006 997 S. It has just under 34,000 miles. It is almost 4 yrs old.



Porsche's maintenance schedule says spark plugs should be replaced every 60,000 miles or every 4 years.



My dealer says I do not need to replace the spark plugs because I have not reached 60,000 miles.


So when should I replace my spark plugs?

 

I agree. I am nearly 5 years old but only 40,000 miles. The book says 4 years. But spark plugs are an item that wears from use, not time. Oil deteriorates just sitting there. But plugs deteriorate from firing. I'm going to go 60,000.

 

NEVER with regards to time expiration, maybe 120,000 miles otherwise. With the advent of DIRECT, even coil on plug, solid state ignition resulting in highly reliable spark voltage/duration/energy and dramatically improved plug gap material spark plugs are no longer really a "wear" item.

I recently changed the plugs, needlessly as it turned out, in our '95 LS400 with over 200,000 miles. Hard to believe for someone as old as I.

 

Plugs deteriorate from usage not just sitting around...

However, deterioration not confined to the plug tip alone.

A case (how strong or weak we can discuss further) could be made for premature replacement -- that is replacement prior to replacement based on miles driven -- if sufficient time has passed.

The owners manual touches upon this by recommending replacement after 60K miles or 4 years.

The concern I'm sure from Porsche is corrosion could result in the spark plug holes and their threads being damaged if spark plugs left installed too long.

Sincerely,

Macster.

 

With the use of unleaded gas, these cars don't foul plugs like they used to. I have a set of replacement plugs ut won't be putting them in until I'm closer to 60,000 miles. Another 13,000 miles to go!

 

Edgy:
Do you plan to change the plugs yourself?

 

I'm not sure quite. I have been studying the directions on the 996 forum and have found that there are several issues surrounding the job that I may not want to get too deep into. The car runs so well right now that I would hate to mess it up in there, and perhaps crack a connector, or drop a rubber seal in there. I may have my independent shop do it. For now--just thinking about it.

 

Here's a shot I took of an engine cut apart for us (seen at the LA Auto Show). Getting to these spark plugs doesn't look exactly simple. There is a very lengthy connector that needs to come out in order to back out the plug. See image:

 

That does look involved.
Thanks for that pic. Would that be the 997.2? Is there a difference?
I thought the plugs were relatively easy to get at on the 997.1; all except one which may require a flexible socket and/or removal of some components to get at.
Either way, when it comes time i doubt i am going to do it myself.

 

This photo is a 997.2 DI engine, but suspect the s.p. area remains the same. On this other shot you can see where the injector is located.

 

I had the spark plugs replaced at 37000 miles/4 years. All old plugs looked real good. Potential issues in long service may include electrode damage, fouling, corrosion and thread freezing in the cylinder head. No reports of this that I have seen on 997 posts. What the effects on peak power are, however, have never been quantified. Probably cheap insurance to replace at some point. Pay your money and take your choice.

 

^^What was the approx. cost to get it done. I might have to do it soon

 

Just back from the shop talking to one of my service guys and it looks like a royal pain to replace these. You really should drop the motor to get to it easier. I certainly recommend a plug change if your miles are up there and the engine is out, anyway. To get to them you have to really take off the muflfers, a couple of brackets, and then each of the individual coils. it's gotten really complex quickly.

 

I would be worried about the plugs getting stuck in the head and damaging the threads in the head when the plug is removed. A spark plug is probably what, 10 bucks? Imagine what it would a pain (i,e $$$) repairing those threads would be.

 

I posed the same question a year ago on this forum. I wound up having it done at the dealer. I had them replaced at 4 years with only 40 K on the clock per Porsche factory recommendation. I think it was about $400 - 450.

Notwithstanding the fact that some people here know better than the Porsche engineers how best to maintain their car I did feel that my 911 had increased power after the changeover.