Lund FF tune - AFR

[Bluemustang]

I am running a Lund FF tune with JLT intake. I've had checked over and revised by Lund and the car seems to run great! Last tune check, fuel trims looked good.

I stopped using E85 a few weeks ago and have been cycling 93 octane back in. I've filled up with 93 octane at least 4-5 times but my AFR ratio still doesn't get all the way back to 14.0. It goes up to 14 sometimes at idle or off throttle situations but it mostly averages 13.3-13.7 while driving. And only hits 14 for a brief second.

Anyone else experience this and is this Normal? I don't want it to be running too rich.

I inquired to Lund awhile back and Greg said that the PCM could have learned to a higher ethanol content. After I did this, it eventually made its way back to around 14 average.

Also I noticed that when my car is cold- say I'm cruising along in 5th, the AFR gauge fluctuates from 12-15. After about 30 seconds it's adjusts and I'm back in mid 13s average. The AFR ratio in general fluctuates more than my stock tune or my Bama tune did.

I am thinking everything is fine because the car accelerates well and no signs of any knock at any point. But I just want to ask questions to be better informed.

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[Jay-rod427]

Could be bad O2's, but more likely you are getting high alcohol content in your regular 93. By law it can only be up to 15%, but who follows the law. hehe

 

[Sasuketr]

I am running a Lund FF tune with JLT intake. I've had checked over and revised by Lund and the car seems to run great! Last tune check, fuel trims looked good.

I stopped using E85 a few weeks ago and have been cycling 93 octane back in. I've filled up with 93 octane at least 4-5 times but my AFR ratio still doesn't get all the way back to 14.0. It goes up to 14 sometimes at idle or off throttle situations but it mostly averages 13.3-13.7 while driving. And only hits 14 for a brief second.

Anyone else experience this and is this Normal? I don't want it to be running too rich.

I inquired to Lund awhile back and Greg said that the PCM could have learned to a higher ethanol content. After I did this, it eventually made its way back to around 14 average.

Also I noticed that when my car is cold- say I'm cruising along in 5th, the AFR gauge fluctuates from 12-15. After about 30 seconds it's adjusts and I'm back in mid 13s average. The AFR ratio in general fluctuates more than my stock tune or my Bama tune did.

I am thinking everything is fine because the car accelerates well and no signs of any knock at any point. But I just want to ask questions to be better informed.

It is pcm related! My pcm also takes some time to adjust the afr on the screen but not as long as yours. You can try disconnecting the negative battery terminal for couple of hours or overnight! It should reset your pcm fuel trim relearning process, and since you have 93 octane in the tank, the afr should fluctuate between 13.8 to 14.2 on idle and 13 at wot!

 

[Bluemustang]

thanks dude I will try that. Do I need to reload the tune after reconnecting the battery terminal?

 

[Jay-rod427]

thanks dude I will try that. Do I need to reload the tune after reconnecting the battery terminal?

no.

 

[18psi]

Mine does the same thing.
But who cares what that gauge shows, plug in the nGauge and have it show you real time lambda numbers from both sensors. that's the true reading. (mine both show around 1 which is 14.7)

 

[beefcake]

every fuel will get different e content....

your never going to have the exact same reading on a ff tank every tank

 

[Jn2]

What is most likely happening is your MAF curve is slightly off and the ECM is taking those random fuel trim corrections and using them to infer the wrong ethanol percentage. While this would not cause any issues since the ECM applies corrections to achieve lambda 1(or commanded lambda) it will have the side effect of inferring the wrong ethanol percentage(usually higher than you really have)and displaying the A/F on the dash as a lower value(although you are still going to be running stoich for your fuel)


What I usually find is with flex fuel logic enabled and certain intakes that have less than ideal MAF placement(JLT, FRPP CJ, and Airaid being the most common) the curve is harder to dial in for the lower end of the MAF period table(which is where most of data used to infer E% comes from), this is usually bc the sensor sits on a curve(CJ FRPP), bad MAF slot(common on some JLTs), or they sit in a spot that doesnt have a long straight section before the sensor. While this doesnt cause much issues when driving and wouldn't lead to catastrophic failure, it's still a minor annoyance that can throw off your fuel trims in random instances, which can lead to flex fuel logic inferring the wrong ethanol percentage.

To find out if this is the case go ahead and log the "Ethanol Percentage % (SAE)" PID and see if this PID is reading higher than 10% when you are on 93. If it is you can reach out to your tuner and see if they can work on your tune a bit more, but honestly it's not much to worry about, it sounds like yours is locking itself in to what is prob e15-20, that low of a inferred value is lower than what most tuners set their flex fuel modifiers for anyway. So all they could really help fix is what you see on the dash. If you leave it as is the car will still run as good as it is running now.

 

[Bluemustang]

Thanks guys. That's good to know that I shouldn't have anything to be worried about.

I appreciate the information.

 

[metroplex]

I know this is a VERY old thread, but I am working on an EcoBoost flex fuel tune (2.7L) and am encountering the same exact issues as the OP. The difference is that the EcoBoost for whatever reason, refuses to mature the inferred AFR. I'm on my 2nd fill up with E10 93 octane and the inferred stoich is still floating around 13-13.10, but using my E85 calculation spreadsheet I should be much closer to E20 by now.

Using HPTuners I can check Inferred AFR Status (Matured / Active Learning) and Inferred AFR Source (Fault Exit / Refueling). Some of the Coyote Mustang owners are telling me they are able to reach Mature within 5-10 minutes of driving or refueling and report LTFT data. On the 2.7 EcoBoost, it stays Actively Learning and never reports LTFT data especially when it is in refueling status. The Fusion has a known issue with its FLI/fuel level input where it fluctuates much more than other Fords and I have noticed it kick into refueling while I am just idling.

I can trick the system by disabling Flex Fuel, starting it, shutting it down, then flashing it to re-enable Flex Fuel. The AFR Source then goes into Fault Exit, and the LTFT data will start to read while it is Actively Learning. But the next time I fill up with gas, the LTFT data goes away and it's back to square one.

With or without the LTFT data, the engine runs fine. I can switch between E10 and full E85 without odd behavior or wild fuel trim swings, so it is adapting. But I don't believe this would pass muster with emissions testing as it is not operating the purge valve or setting LTFT data, so the OBD2 readiness may not complete.

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