How does the ecm calculate injector pw? I would imagine the ve tables,injector constant,coolant tables. But I dont know how it's all tied together...

 

I explained of it in this post ...

https://www.thirdgen.org/techbb2/sho...hreadid=214156

Basically:
GMS of Air / CYL = ((MAP - EGR part press) * CYL VOL)/((MAT + 233) * 128)) * VE

BPW = GMS AIR / (AFR * Injector Flow)

However, there are more adders/subtractors like Acceleration Enrichment, Start Up Enrichment, Injector Pulse Width Correction vs. Battery Voltage, Open Loop change, etc. Also don't forget that the BLM and INT modify it too.

Tim

 

I asked because the pulse width was 4.5ish msec at idle when cold. the pulse width goes down to 2.5ish msec once warmed. So I'm trying to figure out if the ve tables are still far off and closed loop is lowering my p/w by 100% OR if the open loop coolant stuff needs leaned out. There is a few test I'll run tomorrow and then I'll know what table(s) is reducing pw. I do know that the ve table is still off some. The engine is way rich at cold startup(and still a bit rich once warmed). The engine idles rough when cold. I really need to get off my butt and get an ecm bench.....

thanks,

Tim

 

A lot of it depends on how close to startup. Start up enrichment can substantially change pulse widths until it decays away.

Tim