Disassembly: Startup fuel tables

[KeithMac]

How long does it take for the ecu to start using the maf after cold start (say 40 farenheit?). How long are afterstart enrichments active at same temp?. 5seconds?.

[Greg E]

The ECU starts using the MAF the moment you take your hand off the key. The ECU is in cranking mode when you turn the key into the start position.



The bottom two tables should answer your other question.

Using your example of 40 degF there's a 2.5 second 162.5% enrichment factor.

[KeithMac]

Thanks, so primer pulse and decay is only active when key is in start position?, and after start enrichment modifies the injector pulsewidth that's already had the maf reading and baro, iat etc already factored in?.

[Greg E]

Thanks, so primer pulse and decay is only active when key is in start position?, and after start enrichment modifies the injector pulsewidth that's already had the maf reading and baro, iat etc already factored in?.

You got it.

The top table is the percentage reduction of the primer pulse. As the engine cranks, the cranking IPW is reduced to avoid fouling the plugs.

I'm thinking I should re-write this disassembly. It does seem a bit confusing.

[KeithMac]

Thanks for explaining it again!. Makes sense to me now .

Don't suppose you've seen an idle rpm target based on coolant temp on your travels through the code?. Mine seems to target 1500 rpm when cold based on watching IAC step count, dropping to 700 hot.

[Greg E]

Maybe...

http://www.3sgto.org/tuning-engine-e...tml#post211650

There's actually 32 different target idle RPM tables. In chrome I simplified things.

[KeithMac]

Thanks again!, some good reading there.