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Engine start - cranking fuel and prime pulse

General Tuning Discussion

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Hi everyone,

cranking fuel and prime pulse has been on my mind for a while now. Is there a formula to calculate an ideal injector opening time (ms) vs CLT for cranking fuel and prime pulse (ms) vs CLT? The way I have been dealing with this is by trial and error/cranking at different temperatures but it isn't possible to test the settings from -30 to say 110*C.

Hi Jack, unfortunately this really does come down to one of those 'trial and error' areas of the tuning process. in general I do find that with the majority of aftermarket ECUs that the stock cranking and warmup enrichment tables will generally get you very close once the main fuel table is properly tuned so the task is less arduous than it may sound. You may benefit from checking out the following webinar which cover cold start operation on the G4+ ECU. Even if you aren't using the G4+ it will still be beneficial: