Originally posted by DemonSVT:
Originally posted by hetfield:
~~~
As for the actual topic. Yes waste firing is used to help control unburnt hydrocarbons. Yes it is emissions related.
The only effect it has is reducing emissions and wearing out plugs faster. (Well catalyst longevity too) It has no performance implications: good or bad.
This is one of the few times that I must disagree with DemonSVT.
I cannot conceive that there is any measurable improvement in reducing hydrocarbons from the second firing of the plug. For one thing in many modes of operation the original combustion process is still happening. In the modes that it might not still be in combustion, for all intent and purpose, there is nothing that could be easliy ignited remaining. At most, there would only be what little area in the plug gap that would be effected.
When the engineers wanted to keep the combustion going longer to help clean up emissions, they injected fresh air into the exhaust port very near the exhaust valve (air injection). No change in ignition was needed. Without additional air there will not be enough HC to start a new burn.
Anyway, that is my $.02.
Jim Johnson
98 SVT
03 Escape Limited
| 
