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Ford ECU Fuel - Open Loop/Base tab questions

Practical Reflash Tuning

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First vehicle is a 2015 f150 with gen2 coyote naturally aspirated.

From what I understand, outside of power enrichment, there are no direct 3d fuel maps for controlling AFR and AFR is based on a torque model maps.

However in Fuel - Open Loop/Base tab there are a couple of options for setting global Lambda.

One is Base Fuel - Default Target

Which by default is at 1.0 lambda

Second is Manual Control with Enable/Disable menu for manual and a manual override Target which is also defaulted to 1.0 Lambda.

Question is, do these do what I think they do and set the base target for all calculations?

Second question is are these values worth changing or are these values better left alone with exceptions like WOT being handled by power enrichment tables?

I know from EFI fundamentals that rich fuel mixture can be wasteful at best near idle and cruise and down right harmful in excess by leaning out sump oil.

I only ask because from the same course, for N/A engines it is said a lambda of 0.92 is optimal for best power and this seems like a simple way of targeting that.

Edit: Went ahead and just tried this as it has relative low risk of being dangerous.

It does indeed set global target Lambda value.

Considering that this affects all areas of the rev range, I set Target to lambda 0.95 which the motor seems to be very happy with. VCM shows idle load to have Lambda floating between 0.935 to 0.975. Still very safe for idle conditions.

I then set my power enrichment map to a curve that goes from 0.92 to 0.875 lambda based on increasing engine load and RPM.

This seems more ideal to me than the stock enrichment values of 0.85 to 0.82 which is excessively rich considering I only run 93 octane.

Hi Joel, I was thinking of using the same values. Are you still running the engine with these settings?


I'm glad you went ahead and gave it a shot to confirm your suspicions. Like you said, it's not the type of thing that would cause damage when altering it to a slightly richer than stock value for a brief test.

That said, you've likely enriched the engine in areas where it's not necessary. Leaving that value at 1.0, then adding enrichment only at the specific RPM/load areas where it is required, will give you a better result. By better result I mean increase spark plug life, reduced fuel contamination of your engine oil, better fuel economy, better emissions, etc. Where enrichment is not needed, it's not just wasteful, it's less clean and complete combustion so deposits can be left on spark plugs etc.

Thanks, Joel, you taught me something too! I'll leave mine at 1.00.

Also, would there be any reason to increase that value beyond 1.00? Any benefit to that?

Running lean of stoich may be desirable in some off road race use only conditions where catalytic converters are not present, for potential gain in fuel economy for example, but it's unlikely going to be ideal in most situations.

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