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How to Tune the Fuel Charge Cooling Coefficient in a Link G4+

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If you are planning to use the ‘Modelled’ fuel equation in the Link G4+ or Vipec i-Series ECUs running firmware 5.2.2 or later, one of the first tasks once you hit the dyno is to calibrate the ‘Fuel Charge Cooling Coefficient’. This defines how much the fuel being injected will cool the intake charge and has a significant effect on how accurately the ECU can track requested changes in air fuel ratio. In this webinar we will look at the correct approach for tuning this parameter using our Nissan 350Z fitted with a Link G4+ ECU.

Watch: How to Tune the Fuel Charge Cooling Coefficient in a Link G4+

Post your questions below. English subtitles coming soon.

Just curious if you have any tips for configuring the Charge temp approx table?! Seems to be a lot of trial and error! Have you seen much benefit of this over the old school IAT correction only?!

You're right Dan, it isn't a straightforward table to tune. I'm hoping to do some testing on our 86 shortly and see if I can develop a sensible approach to dealing with it. Right now the best place to start is with the suggested starting numbers that Link offer in the help file - I've found these to be reasonable starting points.

If the lambda seems to change too much with heat soak at idle, I tend to weight the charge temp table more towards the ECT in these areas (normally idle/low rpm). It is a lot of trial and error though which I know isn't overly helpful.

Would the coefficient be any different between direct and indirect injection?

Yes it is, although the Link G4+ currently can't control DI engines so it's not strictly relevant. Motec have a similar parameter in their M1 ECU and on our 86 with port and direct injectors, the charge cooling gains are slightly different.