Smoke and Oil usage!
 

Help!

I have a 2002 Porsche Boxter S, whose engine was rebuilt in 2020 by Flat Six Innovations (Stage 1, 2.6L) and now has approximately 25,000 miles (19,000 on my ownership) on the rebuild.

In early June I took a 2,500 mi trip, and the car ran perfectly, but used about 1qt of 5w40 per 1000 miles. Jake Raby assures me that this is normal for his builds with low tension rings.

Late in June I did my first track weekend in the 986, but during the last session I had poor throttle response and the check engine light came on. Durametric showed “Misfire, Cyl. 1.” I then drove the 325 miles home.

I replaced the Sparkplug Tubes (Rauch Speigel and Porsche o-rings) and all six Sparkplug Connectors. Misfire issue resolved.

A few days later, I forgot to replace the oil cap and drove for few days with erratic idle. Replaced the cap and idle returned to normal.

The next morning billowing white smoke at startup! The car has never smoked at startup before.

The following morning, no smoke at startup and drove for a few days, but began to notice tailpipe smoke under hard acceleration (4,500-6,500rpms. I thought that oil may have been sucked into the intake manifold when the cap was missing and would clear up in a few days.

I Reached out to Flat Six and they thought it was probably a falling AOS, even though a manometer test was within the normal range.

I replaced the 6 year old AOS with a genuine Porsche model. Manometer test good!

Zero smoke at startup, but the car is still smoking under hard acceleration. The puff of smoke begins at about 4,500 rpms, but dissipates if I shift or hold the rpms steady and today, after monitoring the smoke at rpm, there was a hesitation in throttle response. I ended the drive and drove home, keeping the keeping the rpms below 3K and the hesitation stopped.

And finally, here’s the kicker, the oil consumption has gone way up! Like a quart per 100-200miles, though I’m not sure how accurate of my measuring. I have absolutely no oil leaks! Every morning I add .2L-.4L but the oil gauge won’t budge off of the bottom mark.

I do all of the work on this car, but I'm baffled and sickened by this problem. Thanks for your help.

Hi Stig
Can you fill in some gaps? Looks like you bought your S 6K mi after the rebuild. Do you know why it was rebuilt (bore scoring or something else)? How do you drive the car - track, fun runs, daily, etc? Do you drive it in cold weather? Also, assume you meant you have a 3.6L displacement now - 3.2 punched out to 3.6.

I ask because I've had a similar experience w/ my Cayman S Sport. Engine rebuilt 2021-2022 because of bore scoring and shouldn't happen again. But it did.

https://986forum.com/forums/porsche-cayman-discussions/87647-oh-no-its-bs-again.html

What you need to do now is scope the engine and see if there's scoring in 1 or more cyls.

Hi Husker,

Thanks for your help. Sorry, it's a 3.6L. I follow Jake Raby's/Flat6's protocol for maintenance and startup. Once the engine reaches operating temps, I drive the way Porsche intended, shift at 3000rpms or above and regularly explore the upper bands. As I live in MT, I rarely drive in winter.

I don't think LN Engineering Nickies bore score, do they?

I may check the scavange pumps and do a blow-by test.

Thanks again.

That's what I thought too, except now 1 of my 6 L&N cyl is scored.