Lean Fuel Trims On Phearable Tune

[D16]

Hopefully someone can shed some light on this particular issue I am having. I am currently running a Phearable tune on my '23 Civic Si (8200 miles). Car seems to be running fine but I did notice the fuel trims are running a bit lean. LTFTs stay steady at +3% while on the highway but as soon as I start city driving they will climb and stay around +7% to +9%. STFTs will stay around +10% while idling with the occasional spike to +20% while city driving. I havent done a WOT pull yet because I first want to make sure its safe to do so. Data logs were recorded a day after the tune was flashed. Both of these logs were recorded while driving the same way(home to work). I included a log of the stock tune as well. Any help would be appreciated.

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[Jester04]

Hopefully someone can shed some light on this particular issue I am having. I am currently running a Phearable tune on my '23 Civic Si (8200 miles). Car seems to be running fine but I did notice the fuel trims are running a bit lean. LTFTs stay steady at +3% while on the highway but as soon as I start city driving they will climb and stay around +7% to +9%. STFTs will stay around +10% while idling with the occasional spike to +20% while city driving. I havent done a WOT pull yet because I first want to make sure its safe to do so. Data logs were recorded a day after the tune was flashed. Both of these logs were recorded while driving the same way(home to work). I included a log of the stock tune as well. Any help would be appreciated.

Any mods?

 

[D16]

Any mods?

Completely stock.

 

[Jester04]

Completely stock.

You have to talk to your tuner then, no way around it.

I don’t deal with Ktuner nor have access to datalogs from them.

 

[D16]

You have to talk to your tuner then, no way around it.

I don’t deal with Ktuner nor have access to datalogs from them.

Ok. I noticed the stock tune was running slightly lean as well. Do you know if these cars run slightly lean from the factory?

 

[Jester04]

Ok. I noticed the stock tune was running slightly lean as well. Do you know if these cars run slightly lean from the factory?

They really don’t run lean, the STFT’s and LTFT’s just add a percentage of fuel to keep afr’s in check. So the Afr’s should still be on target.

Things that can affect fuel trims are intake leaks, more ethanol in the fuel just to give you some examples.

 

[D16]

They really don’t run lean, the STFT’s and LTFT’s just add a percentage of fuel to keep afr’s in check. So the Afr’s should still be on target.

Things that can affect fuel trims are intake leaks, more ethanol in the fuel just to give you some examples.

Yeah the AFR seems to be on target. I did put 1.5 gallons of E85 (E51 here in Arizona) to keep knock control down. Thanks for the info.

 

[360glitch]

Yeah the AFR seems to be on target. I did put 1.5 gallons of E85 (E51 here in Arizona) to keep knock control down. Thanks for the info.

In that case, everything seems to be working as intended.

 

[D16]

In that case, everything seems to be working as intended.

Thats good to know. So the car is pretty much adding more fuel to compensate for the higher ethanol content because it takes more ethanol to produce the same power as regular gas. Is this correct?

 

[Jester04]

Yeah the AFR seems to be on target. I did put 1.5 gallons of E85 (E51 here in Arizona) to keep knock control down. Thanks for the info.

So that is the reason fuel trims are messed up. Not the tune’s fault. I would just run premium and not run ethanol unless you are tuned for it.

 

[D16]

So that is the reason fuel trims are messed up. Not the tune’s fault. I would just run premium and not run ethanol unless you are tuned for it.

The highest grade we have here is 91 and I run that all the time but my knock control was hitting 0.6. Apparently we have crappy gas here. On Phearables website they recommend adding 1.5 gallons of E85 to get 93 octane for better performance and adding E85 also brought my knock control down to 0.49. Are there other ways of reducing knock control without using E85?

 

[Shankmeyster]

A proper tune from one of the Etuners. Off the shelf tunes work differently on every vehicle.

 

[D16]

A proper tune from one of the Etuners. Off the shelf tunes work differently on every vehicle.

Do you know of any good tuners locally in Phoenix?

 

[Jester04]

The highest grade we have here is 91 and I run that all the time but my knock control was hitting 0.6. Apparently we have crappy gas here. On Phearables website they recommend adding 1.5 gallons of E85 to get 93 octane for better performance and adding E85 also brought my knock control down to 0.49. Are there other ways of reducing knock control without using E85?

So you can use ethanol but it will tax the fuel system more. The best bet would be to custom tune it to the gas you actually have available, or just add some higher octane fuel to bring it up. But honestly the tune should be dialed down to the fuel that is readily available.

 

[Shankmeyster]

Do you know of any good tuners locally in Phoenix?

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