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Raw Cranking Fuel

EFI Tuning Fundamentals

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Discussion and questions related to the course EFI Tuning Fundamentals

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How does one go about determining what kind of PW is needed during cranking? Engine is spinning slower than normal operating speeds which allows for an extremely long cycle time to inject but I assume we need to account for pumping loss in addition to that. Is there a general rule of thumb people apply after configuring the base fuel requirement calculations or can the same math be applied to cranking?


Can you post a screenshot of what tables you are looking at in an ECU? What's the background on the project? What engine, what injector, What fuel?

Hey Anthony, what are you tuning? Most aftermarket ECUs don't specify cranking fuelling in terms of injector pulse width, but rather as a percentage of the main fuel table values in that area. Generally though, regardless what ECU you're tuning, these numbers are found via testing as opposed to calculation. Generally, despite the long cycle time, you also find you'll need a lot more fuel than you'd think in order to get the engine starting cleanly.

Here is an example of the tables I am referring too.

Back ground on this motor is a 2.0 B18C 12.5:1 compression 4 piston outlaw head ID1000s on e85 pro3 intake pro2 exhaust

Never had a serious cranking or starting issue (that wasn't mechanical) because most of these base maps I've dealt with thus far give a good general starting point after configuring everything. I guess the question was just a general one for from scratch calibrations without having the help of a preset base map to start building from or in the scenarios of running alternative fuels to get it to start more easily. Good can often still get better.

Just started watching the tuning cold start webinar 016 hopefully it sheds a little more light. =)

In addition to logging cranking, my wideband will reset during cranking and doesn't give me feedback until post start enrichment kicks in. Would it be feasible for this portion of the tune (when needed) to have a second power supply for the wideband so it doesn't reset?


Attached Files

ethanol fuel is its own animal due to the poor vaporization when cold. Did you look at the ethanol fuel/flex fuel course?

Haven't checked it out yet but will in the near future =) I understand the concept though. It's mainly my summer toy but sits in storage from October to march so doesn't see the cold months here in the pacific northwest.

Neptune doesn't utilize a flex fuel map so I typically drain the tank and toggle maps between the e85 and 92 gas when needed; getting old though. Going to switch in the next month or two to a more capable ECU that can flex fuel and allow me to utilize COP!

So much to learn! so little time!

Do any of the videos or webinars cover tuning with methanol, m1/m5? I hear it's extremely corrosive but makes killer power; attractive thing for us NA guys where every 10 hp costs 1 testicle.

Thanks for your help Raymond!

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