Afterstart enrichment (choke)
Afterstart enrichment (choke) As a general rule when putting in a bigger cam do you need more or less afterstart enrichment or do the dynamics not change much and you dont really need to mess with that?
You don't really need to mess with afterstart enrichment...
The key to the dipping idle is to work on the startup airflow correction and startup friction airflow correction tables- add about 2gm/cyl to the correction tables, decrease the decay factors by about 50% and increase the delay by about 50%.
This gives it more air on startup and slows down the drop in air to reach the values in the running airflow tables. The slower transition allows the engine to catch its breath so to speak before dropping down to normal idle.
There are spark tables that can also help out if you are running a really big cam - you can narrow down the idle corrections so they don't swing so much trying to correct a fluctuating idle...
The key to the dipping idle is to work on the startup airflow correction and startup friction airflow correction tables- add about 2gm/cyl to the correction tables, decrease the decay factors by about 50% and increase the delay by about 50%.
This gives it more air on startup and slows down the drop in air to reach the values in the running airflow tables. The slower transition allows the engine to catch its breath so to speak before dropping down to normal idle.
There are spark tables that can also help out if you are running a really big cam - you can narrow down the idle corrections so they don't swing so much trying to correct a fluctuating idle...
My car ended up way over-enriched after cam swap,
the higher MAP at idle will increase commanded fueling
underlying the afterstart, and low RPM VE always
needs work to not be bogus-high airflow, bogus-rich
fueling. Better to deal with the open loop fueling and
VE first before messing with the afterstart but I did
take a lot out of it, a bit at a time, as well as bumping
out the friction airflow & decay to make it more stable
immediately after catching.
the higher MAP at idle will increase commanded fueling
underlying the afterstart, and low RPM VE always
needs work to not be bogus-high airflow, bogus-rich
fueling. Better to deal with the open loop fueling and
VE first before messing with the afterstart but I did
take a lot out of it, a bit at a time, as well as bumping
out the friction airflow & decay to make it more stable
immediately after catching.
