986 Forum - The Community for Porsche Boxster & Cayman Owners - View Single Post

12-06-2005, 06:34 PM

Here is some interesting info about smoke on start-ups:

"The smoke can be from couple different things and applies to all Boxsters and 996's. One is do to oil getting into the combustion chamber. The oil can seep past the rings on rare occasions or more so get past the valve guides. The oil seeping past the guides is usually seen when the car is driven and then parked on an angle sloping front to rear or visa versa and not side to side. The front to rear slope retains the oil forward or rear in the cylinder head depending on the bank and the slope. A forward slope in a Boxster allows this to happen in bank 1-3 and the opposite for bank 4-6. The 996 would be the opposite bank infiltration do to the configuration of the engine.

A second can be do to the gas itself and or the spark plugs. The gas is blended differently for different regions and can degrade at different rates. This degrade and different blends with Ethanol can glaze or foul the spark plugs. Cars that do not tend to use a full tank of gas within the 30 days will do this. Once the spark plugs are glazed or excessive soot or carbon has formed from the gas the problem will persist. The The car smokes in these cases do to the DME upon cold starts is adding more fuel to compensate for the absorption of the fuel by this soot or glazing. These coatings act like a sponge and soak up this fuel so more fuel is added. Once the car is running and goes into Lambda mode it is now compensated for and the smoke stops. All of this happens in only the first few minutes of start up.
To remedy this it is advised to add a cleaner with Techron on a regular basis and initially change the spark plugs. The first several tanks should get twice the amount of cleaner as suggested and then reduced to the specified amount on the can.

Scott Slauson - PCA WebSite - 12/4/2005"

12-06-2005, 06:34 PM	#10
bmussatti Guest Posts: n/a	Here is some interesting info about smoke on start-ups: "The smoke can be from couple different things and applies to all Boxsters and 996's. One is do to oil getting into the combustion chamber. The oil can seep past the rings on rare occasions or more so get past the valve guides. The oil seeping past the guides is usually seen when the car is driven and then parked on an angle sloping front to rear or visa versa and not side to side. The front to rear slope retains the oil forward or rear in the cylinder head depending on the bank and the slope. A forward slope in a Boxster allows this to happen in bank 1-3 and the opposite for bank 4-6. The 996 would be the opposite bank infiltration do to the configuration of the engine. A second can be do to the gas itself and or the spark plugs. The gas is blended differently for different regions and can degrade at different rates. This degrade and different blends with Ethanol can glaze or foul the spark plugs. Cars that do not tend to use a full tank of gas within the 30 days will do this. Once the spark plugs are glazed or excessive soot or carbon has formed from the gas the problem will persist. The The car smokes in these cases do to the DME upon cold starts is adding more fuel to compensate for the absorption of the fuel by this soot or glazing. These coatings act like a sponge and soak up this fuel so more fuel is added. Once the car is running and goes into Lambda mode it is now compensated for and the smoke stops. All of this happens in only the first few minutes of start up. To remedy this it is advised to add a cleaner with Techron on a regular basis and initially change the spark plugs. The first several tanks should get twice the amount of cleaner as suggested and then reduced to the specified amount on the can. Scott Slauson - PCA WebSite - 12/4/2005"