So I had a strange occurrence yesterday.

I took the car up to speed on the highway, at around 4k to 5k RPM (in third under throttle) the car became jerky almost like it was hitting a limiter, and somewhat lost some power. Immediately when that happened the check engine light came on and was flashing for about a minute after I reduced the speed, and then went off altogether and normal cruising speed.

It’s off now, with no problem driving it around at normal “human speeds”.

Yesterday I had an ECU tune that added a whopping 80hp, however speaking to the chaps responsible for the software tune they seem pretty adamant that the program is good. The caveat is I felt something similar but not as pronounced a week ago (before the tune) going up a mountain pass also under full throttle load and for a split second I saw the CEL flash once - so don't think it has anything to do with the tune.

The car has around 70km (43k miles) on it.
Is this the clutch slipping (still stock - hasn't been replaced) or would this be the plugs that need replacing or something else?

 

It's not the clutch. A slipping clutch has completely different than what you described. Sounds like your plugs are misfiring. If your plugs are still the original factory ones, it's probably time to replace them. I've had it happen to me too.

 

sounds like an 02 sensor went bad.. if its not your plugs

 

Thanks - Just spoke with a few folks and it looks like it may be the plugs.

Would I have to get the Coils replaced at the same time too? Last time they were replaced was at the 40,000km service (30,000km ago) so I guess it's time again.

Any recommendations on type of plugs and coils - does it matter? ...or just replace them with the OEM Bosch (I think?).

 

Perfect... LOVE THESE FORUMS!
Everything one needs is here
https://www.6speedonline.com/forums/...97-turbos.html

 

Read your post again. Another local 997TT had a similar problem as yours.

It may not be the plugs/coils. Check your PM for what the issue may be.

 

Bump. Did you end up getting to the bottom of it yet? I had a similar strange occurrence happen a few days back myself.

 

Nope - I have not touched sport mode in over a week and a half!
...and haven't had an opportunity to test the Softronic tune either (due to this problem). Don't want to take a chance of making it worse before I can determine what it is. I'm pretty convinced that the plugs are the culprit, having 30,000km on them. Already scheduled a visit, early next week, to have them replaced. I'm hoping that will solve the problem.

Reason I'm thinking it's something else (AKA Plugs) other than the tune is that I noticed the same symptoms (only much less pronounced), throttling up a mountain pass before the tune. So common logic would state that it is something else, like those pesky plugs.

Additionally I have read that although Porsche states 40k before replacing them, they should be replaced in the 20,000-30,000km mark, on aggressively driven cars. Not a cheap exercise either, have a quote in just under C$1000 for the operation.

Keep me posted what you find out - curious to know. Last thing I want is to be operating on something that's not the problem.

 

Are you sure it isn't PSM kicking in? Was it the PSM light that lit on the dash?

 

CEL, it's on permanently now :P

 

Did you check out the fault code number with durametric?

 

Haven't been able to as I was using the older cable. Sent it back a week ago to have it upgraded to the durametric one, but with the Memorial day weekend, everyone seems to be on holiday, so will only be getting the new one sent out next week. I will have it checked before getting the plugs changed when it gets to the service center.

Yeah... dying to know what the code says!

 

with a tune worn plugs become even more evident and you will see that stuttering misfire. 40k is well past prime on the plugs. On tuned cars most here are seeing about 15k mile plug life before issues

 

Obviously the life of the plugs is being dramatically shortened due to the inevitable rise in combustion temperatures. Using a colder range plug will help, but having efficient intercoolers would be a more proactive way to help reduce the rise in combustion temps. Maybe these .2tt coolers are a cheap alternative afterall. The cost of changing out spark plugs at @1000.00 every 10 to 15K is expensive over time.

 

Interesting - never thought of the inter-coolers as a proactive way to extend their life. Would be really curious to get my hands on any empirical evidence to back that up.
...any one???