jk335

is there soot on the back bumper?

Todd in PA

My speed yellow rear bumper gets lots of fluffy black soot on it and the pipes are completely sooty black inside. I also use about a quart of oil in less than 1000 miles. Break in per the manual, and the dealer says this is all normal. Not to me it isn't! FYI I just used Bar Keepers Friend to clean my exhaust pipes with an old towel and the shoe shine method. They look great. I made a wet paste and applied it with the old towel.
http://www.amazon.com/Bar-Keepers-Fr.../dp/B000QYLEBE

stevepow

I have added about 2.5 quarts over 4K miles (along with one oil change). Seems like the variations on this are huge. Still, the oil consumption is worse than any car I have had except a '74 Vega whose engine was on the verge of death.

Soot is not terrible, but my tips are definitely not brushed chrome at the moment - more like smokey pewter. Baby needs a bath big time and nothing but rain in the forecast.

chago996

On the topic of soot, I have an observation. A week ago, me and 2 other friends did the short track event at El Toro air base with POC. I brought my '01 996 and they brought their new to them '07 GT3. One of those GT3 was previously owned by a really nice gentleman who is very involved with POC and came to the event to help them learn the cars on the track. He also owns 3 cup cars which raced last saturday at sebring, so very knowledgeable on things GT3 and Porsche. He pointed out how the exhaust tips on our 3 cars where heavily sooted, and to take a look after the first session and witness how clean they would become. We ran 15-20 minute sessions, no passing, but flat out. Checked exhaust tips after 1st session and long and behold, all 3 cars, were clean as new. Different engines. He said these engines run very rich and unless driven very hard, will accumulate the soot. Can't help u on oil consumption, though. Mine didn't burn any in 5 sessions, and has never needed any topping off in 110k miles, but its not DFI.

ADias

It does not help to drive DFI/PDK cars in SC Normal at low revs in city traffic either... PDK Normal Auto brings revs down far below 2kRPM. This is why, when driving in traffic, and city driving, I drive in M and keep revs a bit higher - no soot.

mdrums

ADias, what RPM are you driving at? I drive in manual too and keep the rpms at 2.5-3k and it helps a little on soot but the tips and rear of the car still soot up. Track driving a 4-7k rpms the tips get a white/grey clean look to them just like the race cars.
With my 09 Carrera S (DFI) at the track I burn around .5 quart of oil a day. 2 day event I can burn a quart in 300 track miles. My 07 Carrera S would hardly burn any oil. the tips did not soot up nearly as fast as on my 09 but they also turned that clean grey white at the track.

Todd in PA

Well I have a 6 speed and rarely see 2k on the tach, I am always enjoying the car. I never lug the motor and love to hear the exhaust note with the top down and healthy throttle applications. The car is blazingly quick and balanced and a joy for any driving enthusiast. As a past driving instructor for Riesentoter PCA, I routinely practice my heal and toe downshifts and drive the car with glee.
Still have a crap load of soot.

ADias

I keep it above 2kRPM.

soverystout

Just adding my .02.

My 06 Mazdaspeed6 (DD) in direct injected andd turbo charged (2.3L 4cyl).

The car is a soot making machine. I have owned it since new and I now have 56K on the clock.

The mufflers on my car are unbelievable. Someone cut one in half to reveal these bizarre chambers which look way different then more conventional mufflers that were almost created to collect the soot. Folks who switch to aftermarket exhaust (they make a singel 3" exhaust for the speed6) have lots of soot issues.

May just be the nature of the beast. Porsche was late to the game with DI. I am surpised they haven't taken it a step further to address the typical complaints associated with DI engines.

kosmo

Ok I'll admit this confusing as Im not an engineer. SOOT is a result of incomplete combustion. So I ask- whats happening in the chamber? Is there too much fuel being delivered? Is there not enough air? Running the engine at a higher RPM and thus creating more heat and a more complete combustion makes sense to me.
Thats it! Going forward Im using race fuel and running at 6000rpm all the time!

GrahamML

Do you know if the dealer double checked the Rear Main Seal? I have a similar issue on a '06 S. Bought the car 1 year ago with 7500 mi on it, 14000 now and still gulping oil. THrough other threads here I am on the verge of taking it to the dealer to have them do similar checks to what you described, including the RMS.

jk335

good idea, never thought that plaugued the 997.5...

Mike in CA

After a drive I always find black dust on my silver back bumper. When I wipe it down with some Qwik Detailer and a white towel, I also find the same stuff on the bumper behind the rear wheel wells and to a lesser extent on the fender/door panel immediately behind the front wheel wells. It looks exactly like the black stuff I clean off my wheels. I had the same issue with my silver '99 996 and '07 Boxster S,which were not DFI cars. My assumption is that this is brake and perhaps rubber dust. Clearly there is no soot coming off the front wheels. Also FWIW, my tailpipes don't show unusual black build up and my car burns almost no oil.

I'm confused by this whole soot issue. If DFI engines really generate this much soot, how are they able to pass (which they apparently do) strict emission controls for particulate matter and other pollutants?

stevepow

Took a drive in Sport+ yesterday - wow - kinda fun though, if not a bit over the top for the street! I agree though - I'm thinking my worst soot accumulation was when I was playing around with D/normal for a week - amazing gas mileage though. For those loathing the low revs with PDK, S+ will get you over that.

ADias

Sport Plus Auto is overkill for the street (it shifts at redline). Sport is just right. But in city traffic I often prefer M to keep it in the gear I want.