Kevinmacd

I can understand changing out the old coils since the 996 coils would crack and short out. The 997 coils were redesigned with better potting material to keep them from cracking! Therefore change interval on the 997 coils should last a lot longer and not have to be changed out unless cracking is evident.

gophaster

These are my thoughts as well...a few months ago I replaced my coils (and plugs). They were the original 996 part # coils. They all looked very decent except for 1 that you could see the beginning of a small crack.

I still don't have a tune on the car and I plan to do the plugs at 10k intervals (which should last quite a while considering how few my opportunities to drive her have been lately) but I'm planning (hoping!) these revised 997 coils will last at least a couple plug changes so I will then just inspect the coils and change the plugs only, assuming she is still running smooth as silk

Carlo_Carrera

Is that engine twin turbo charged? And did they increase boost pressure too?

We are not talking about a small increase in overall engine temperature for efficiency. We are are talking about a significant increase in boost pressure 25-30% and this a significant increase in combustion camber temperature from the ECU tune.

Dock

In addition to heat, higher RPM decreases plug life; everytime a plug fires, some material is removed from the electroid. Cruising around at 4000 RPM versus 3000 RPM means more plug firings, and more wear.

napoleon1981

Yes I thought so too. The car came with some service records, and interestingly the 30k mile service was performed at Stevenson Porsche in Colorado. There was a note on the bill that plugs were not changed. When I went in there I could tell they had never been changed, because all the heatshields were still glued together and had never been moved.

fung0001

yes
you may be right
i have tuned my bmw for higher boost and never follow the manual for plugs change

Carlo_Carrera

Why would getting an ECU tune cause the owner to drive around at 4k vs the usual 3k RPM?

993GT

BMW N54/55 engines love their plugs too, I do plenty of them...any engine with a high cylinder load does...

Warehouse33.net

Very true, I sell lots of the upgraded NGK plugs for the n54/n55 engines.

-Jason

996tnz

Mine used to boost too on a freeway cruise when stock. But one of the first things I noticed about a 93 Octane tune and 100-cell catted exhaust was that my car no longer got into that .1,.2 kind of mild boost on the commute to work at all, and would now only start to boost some 7-10 MPH higher up the dial. The exhaust probably helped a little, but I mostly put it down to the tune delivering more torque at the same revs (as you touched on). She now had enough extra power to meet the load put on her at 70 odd mph without needing to spool up her turbos to help.

More combustion heat is partly addressed by running a cooler grade of plug of course, but, yes, as you say, those higher combustion temperatures still age the plugs faster and more frequent replacement is recommended for tuned cars. I left replacing the cooler ones that came with her upgrade until I could feel some fall off in performance, which happened recently around 20,000 miles later. So they'll get done before I track her again. No major symptoms but she just started to feel a bit 'boggy' and off-color/slightly hesitant at lowish revs. Will aim to do them every 10,000 miles I think.

How close a tuner chooses to run to the detonation point is pretty much down to the tuners own taste and risk appetite I think. Leaner is a bit faster but also less safe. One reason I chose Kevin (and I know there are others) for mine is that he runs demonstrably (one of the beauties of his datalogger) safe tunes. As I understood it, that meant basically maintaining the factory knock control, while tuning for our local 93 octane fuel - as directly measured in my own car. And likely with some amount of sacrificial fueling towards the limit of her expanded performance envelope to proactively cool the chambers. Meaning that knock control doesn't need to kick in as often or as hard. Which is good as when I'm right foot flat I'd rather she cool herself first with a little extra fuel than by having more and more timing pulled at the cost of power.

Hopefully someone here can confirm or deny my understanding though, as I'm no tuner and there are a few variables at play...