Post Start Enrichment - Implementation
Posted: Fri Mar 04, 2011 12:59 am
Fred was kind enough to point me here:
http://www.e30tech.com/forum/showpost.p ... ostcount=2
and... My poor hackles - all raised now! No one likes to see "injector pulse time" for anything - people who swap injectors regularly (or perhaps have dual fuel rails, etc) have to constantly make changes in their head - let alone account for things like battery voltage, fuel temp, and a hundred other things an intelligent system could take into account.
As an aside, 500 cc injectors on a 1 ms pulse deliver 8 ul (micro-liters, or 0.008 cc's) of fuel.
Back to cold starts:
Fred pointed out that while enrichening or IAC'ing up for a preset number of CYCLES makes the most sense (roughly the amount of heat generated is dependent on the number of rotations - though of course one could get carried away and use something like amount of fuel consumed and factor in the time spent rotating for the heat to soak etc) the simple matter is no one wants to think in terms of cycles.
Perhaps, then, a good compromise is to list it in terms of idle-equivalent time: Number of cycles which would happen during 10 seconds of standard idle (which will likely be 6 seconds of elevated idle and taper).
I suppose I've always liked the idea of actually having a cold-idle/after-start idle target - then time is appropriate. So perhaps this whole idea is a bit useless.
At the risk of removing too much control from the user, how about "After start idle target" which could be an RPM's-vs-Time. This would lead you to consider having the enrichment back to a function of time under the assumption that the engine hits it target - but behind the scenes, just let it use the calculated cycles and be done with it.
What do you all think?
http://www.e30tech.com/forum/showpost.p ... ostcount=2
and... My poor hackles - all raised now! No one likes to see "injector pulse time" for anything - people who swap injectors regularly (or perhaps have dual fuel rails, etc) have to constantly make changes in their head - let alone account for things like battery voltage, fuel temp, and a hundred other things an intelligent system could take into account.
As an aside, 500 cc injectors on a 1 ms pulse deliver 8 ul (micro-liters, or 0.008 cc's) of fuel.
Back to cold starts:
Fred pointed out that while enrichening or IAC'ing up for a preset number of CYCLES makes the most sense (roughly the amount of heat generated is dependent on the number of rotations - though of course one could get carried away and use something like amount of fuel consumed and factor in the time spent rotating for the heat to soak etc) the simple matter is no one wants to think in terms of cycles.
Perhaps, then, a good compromise is to list it in terms of idle-equivalent time: Number of cycles which would happen during 10 seconds of standard idle (which will likely be 6 seconds of elevated idle and taper).
I suppose I've always liked the idea of actually having a cold-idle/after-start idle target - then time is appropriate. So perhaps this whole idea is a bit useless.
At the risk of removing too much control from the user, how about "After start idle target" which could be an RPM's-vs-Time. This would lead you to consider having the enrichment back to a function of time under the assumption that the engine hits it target - but behind the scenes, just let it use the calculated cycles and be done with it.What do you all think?