Target different Lambda at idle 2018 Mustang

[WesDuenkel]

Is there a setting or a method to target a different Lambda...at idle? My assumption is that in anything other than "power enrichment" mode, the target lambda is 1.0. Is there a way to target, for example, target lambda 1.2 at idle? (Ultimately, this is to counteract a fat fuel trim with ghost cam tune.)

[K44]

You can target a different lambda by ECT. If it can be done by RPM I don't know how.

[engineermike]

I think you have to force it to stay in cold fueling in order to force a different idle lambda, and I don’t know if there are unintended consequences associated with this. Like will it will go into PE if it’s using the cold fueling table? I don’t know.

I think a better, but certainly not perfect solution, might be to lock the fuel trims (assuming your maf and injectors are properly calibrated).

[WesDuenkel]

I think a better, but certainly not perfect solution, might be to lock the fuel trims (assuming your maf and injectors are properly calibrated).

That's a good idea. Not to be lazy, but which setting is that offhand?

[engineermike]

You could disable closed loop using 12115 or disable LTFT using 230.

There may be better ways to do it by disabling the PI controller just in the load and speed range in question using 47637 and 47000, or even fool the o2 sensor bias in 32905 and 32908.

Just spit balling here.

[jadenbender]

You could go into the Fuel Base Cold table and mess with the lambda values in there but you may need to trick the car to always stay in the cold start table.

[veeefour]

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[murfie]

Targeting a different commanded lambda, just changes the stoich AFR at the desired area.This isn't an appropriate way to correct closed loop O2 error.

If the O2 sensors are seeing blow through air, reporting lean, this will not correct the error they report. It would have to be done using SD blow through. Or abandon the closed loop fueling all together.

On the other hand if they are saying a cam lope tune is rich, you should be able to correct that by modifying they way it determines mass air(MAF) or mass fuel(injector flow, fuel pressure) at idle. If its saying rich, and your changes do not have an effect, I would be looking at injectors for leaking fuel.

[WesDuenkel]

Targeting a different commanded lambda, just changes the stoich AFR at the desired area.This isn't an appropriate way to correct closed loop O2 error.

If the O2 sensors are seeing blow through air, reporting lean, this will not correct the error they report. It would have to be done using SD blow through. Or abandon the closed loop fueling all together.

On the other hand if they are saying a cam lope tune is rich, you should be able to correct that by modifying they way it determines mass air(MAF) or mass fuel(injector flow, fuel pressure) at idle. If its saying rich, and your changes do not have an effect, I would be looking at injectors for leaking fuel.

To clarify: with my cam idle tune, my short term trims are adding about 12% fuel to get the mixture to stoichiometric because (I assume) there is an excess of blow through air. The goal is to stop the PCM feeding extra fuel because (I assume) they're reading a false lean condition from all the blow-through air.

The ultimate goal is to keep my cammed tune AND keep the cats alive.

Am I maybe barking up the wrong tree on this?

For what it's worth, here is my tune file. I'm using Mapped Point #10 at idle.

[engineermike]

There may be better ways to do it .... fool the o2 sensor bias in 32905 and 32908.

I just checked, and the Boss "track key" factory ghost cam cal uses O2 sensor bias to address the issue.

[WesDuenkel]

I just checked, and the Boss "track key" factory ghost cam cal uses O2 sensor bias to address the issue.

Interesting. Thanks for sharing this! My only concern with this approach would be: the ghost cam "ramps in" with ECT. If I change the sensor bias to, say, be 10% leaner at idle, won't that make the idle mixture too lean until the cam overlap brings things back to stoich?

I wonder if doing some type of blow through adjustment in the idle speed range will be a better approach since it is specific to when mapped point 10.

As such, any suggestions on blow through values to use as a tarting point?

[engineermike]

I can’t help you with that but if the issue is specific to mapped point 10 and blowthrough is your solution, and it’s a narrow rpm range you’re concerned with, then there is only 2 numbers you have to mess with (slope and multiplier).

[murfie]

I wonder if doing some type of blow through adjustment in the idle speed range will be a better approach since it is specific to when mapped point 10.

As such, any suggestions on blow through values to use as a tarting point?

The quad, slope, and offset need to indicate you are above 100%VE to use the blow through slope. Math behind it is more than most want to do. You need to log MAP, RPM, and MAF to get the airmass to pressure relationship.

For blowthrough you do manifold pressure over airmass to get inHg/lb.

31.88inHg/ .0017lb =18,753 inHg/lb. This is 100% VE with 0 offset and 0 quad if max MAP is 31.88.
The blow through line will be a value lower than that.

Default 18995.8 comes out to 32.3, just 0.5 higher than the max map at 100%VE, so even just enabling it, it will not use it.

Example of a guess at a VE curve put into HPT calculator and seeing what it came up with.
BT MP10.jpg

[F150Farmer]

In the closed loop bias tables, how much does changing the voltage bias in the table translate to the amount of fuel, or change in lambda?