Help me understand flex fuel tunes

[sms2022]

Been looking into a flex fuel tune. My understanding is that the primary issue with them is they go very rich if an air leak develops because the computer infers flex fuel content from how rich/lean the wideband measures the exhaust during the first few minute of a startup.

if this is the case, how does ford get around this issue with the factory f150 flex fuel tune?

Unfortunately the companies that include a fuel sniffer as part of their flex fuel package don’t make one for a Gen 3.

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[shogun32]

call Livernois. Get their flex tune. Live happy.
And quit stabbing your intake piping with an awl and you won't develop air leaks.

 

[sms2022]

call Livernois. Get their flex tune. Live happy.
And quit stabbing your intake piping with an awl and you won't develop air leaks.

I live about 40 minutes from them. I might have to make a trip down there to talk to them

 

[mejohn50]

Two things:

1 - the Ford logic includes safeguards that tell the system not to infer an ethanol content change unless a fuel refill happens. So, theoretically, if a vacuum leak happened without a concurrent fuel refill it should throw a code. If, by extreme coincidence, you developed a vacuum leak at the exact moment you did a fuel refill it could throw the system off. The likelihood is low, but it’s possible, and it’s part of what I don’t like about the OEM logic. Though I’ve tested the OEM logic on a boosted gen 3 with good results.

2 - PCMTEC offers a flex fuel system that uses an ethanol content sensor in the fuel line. There are tuners that offer this system now for gen 3. I’m self-tuning my car and running this system on a boosted gen 3.

 

[Rolls]

As MeJohn alluded to there are quite a few gotchas with the OEM flex system which is why Lund and other companies won't offer it on PD cars. Too much risk of user error and an engine going pop.

 

[sms2022]

Two things:

1 - the Ford logic includes safeguards that tell the system not to infer an ethanol content change unless a fuel refill happens. So, theoretically, if a vacuum leak happened without a concurrent fuel refill it should throw a code. If, by extreme coincidence, you developed a vacuum leak at the exact moment you did a fuel refill it could throw the system off. The likelihood is low, but it’s possible, and it’s part of what I don’t like about the OEM logic. Though I’ve tested the OEM logic on a boosted gen 3 with good results.

2 - PCMTEC offers a flex fuel system that uses an ethanol content sensor in the fuel line. There are tuners that offer this system now for gen 3. I’m self-tuning my car and running this system on a boosted gen 3.

number 2 is exactly what I’m looking for. Don’t mind spending to get the right system. Would you mind sharing (PM is fine) the names of the tuners you’re talking about? All I have found is Lund but I’d like to talk to a couple of tuners first before picking one.

 

[HKusp]

Wengerd, Shoemaker and Ortiz. Let Lund do their thing on their fanboys.

 

[sms2022]

Wengerd, Shoemaker and Ortiz. Let Lund do their thing on their fanboys.

Thanks. My thoughts also on Lund. That’s why I was asking about alternatives.

 

[Angrey]

In your weird scenario, yes, if you happened to be running an inferred flex fuel tune and just so happened to get a "leak" (it depends on whether you're boosted or not whether that ends up being fuel added or subtracted).

First, no tuners (that I'm aware of) will do inferred flex fuel on a boosted setup. As above, PCMtech offers TRUE flex fuel with the sensor. But no one before that was willing to do the inferred version with a blower.

So I'm assuming you're naturally aspirated. If that's the case and you have a "leak" you're getting more air sucked into the motor than is being metered at the MAF. That normally results in the short term trims adding fuel because the 02's are telling the computer they're seeing more residual 02 than what should be based on the MAF signal. It'll adjust that way until the trims reach 20% and then throw a code at you.

If this was to occur (n/a) at the exact same time as your reset (through a fuel level change) the computer would infer that the additional oxygen is because of higher ethanol content (and not enough fuel is being squirted). The result would be the same for adding in more fuel however, the danger there would be that it would also try to add more timing based on the inferred (incorrect) ethanol content.

Bottom line is, yes, if you somehow sprung a vacuum leak EXACTLY at the moment you tripped an ALC% relearn, some less than optimal things could occur. But all the typical protections would still be in place.

Just avoid all that and go with PCMtech and use a true flex fuel sensor. You still have all the previous issues of an air leak, but the computer is no longer mixing the two issues, it's calling for proper fuel flow based off the ethanol sensor input and then it just would recognize something off with the wideband readings.

 

[sms2022]

In your weird scenario, yes, if you happened to be running an inferred flex fuel tune and just so happened to get a "leak" (it depends on whether you're boosted or not whether that ends up being fuel added or subtracted).

First, no tuners (that I'm aware of) will do inferred flex fuel on a boosted setup. As above, PCMtech offers TRUE flex fuel with the sensor. But no one before that was willing to do the inferred version with a blower.

So I'm assuming you're naturally aspirated. If that's the case and you have a "leak" you're getting more air sucked into the motor than is being metered at the MAF. That normally results in the short term trims adding fuel because the 02's are telling the computer they're seeing more residual 02 than what should be based on the MAF signal. It'll adjust that way until the trims reach 20% and then throw a code at you.

If this was to occur (n/a) at the exact same time as your reset (through a fuel level change) the computer would infer that the additional oxygen is because of higher ethanol content (and not enough fuel is being squirted). The result would be the same for adding in more fuel however, the danger there would be that it would also try to add more timing based on the inferred (incorrect) ethanol content.

Bottom line is, yes, if you somehow sprung a vacuum leak EXACTLY at the moment you tripped an ALC% relearn, some less than optimal things could occur. But all the typical protections would still be in place.

Just avoid all that and go with PCMtech and use a true flex fuel sensor. You still have all the previous issues of an air leak, but the computer is no longer mixing the two issues, it's calling for proper fuel flow based off the ethanol sensor input and then it just would recognize something off with the wideband readings.

My thoughts exactly based on the research I did after I made this thread. I reached out to wengerd based on the above suggestion.

 

[ChitownStang]

As MeJohn alluded to there are quite a few gotchas with the OEM flex system which is why Lund and other companies won't offer it on PD cars. Too much risk of user error and an engine going pop.

So how is Livernois doing the Flex tune with no issues. They say completely safe and 50 state legal.
I’ve run it for 1.5 years now with 0 issues and I change fuel from summer to winter and winter to summer .
Per their instructions, When I fill up, I just drive the car nicely for first 15 min and don’t sit at idle.
Do they have the secret sauce?
I know they work closely with Ford

 

[Angrey]

So how is Livernois doing the Flex tune with no issues. They say completely safe and 50 state legal.
I’ve run it for 1.5 years now with 0 issues and I change fuel from summer to winter and winter to summer .
Per their instructions, When I fill up, I just drive the car nicely for first 15 min and don’t sit at idle.
Do they have the secret sauce?
I know they work closely with Ford

You have a blower car?

 

[Magnetic Stang]

So how is Livernois doing the Flex tune with no issues. They say completely safe and 50 state legal.
I’ve run it for 1.5 years now with 0 issues and I change fuel from summer to winter and winter to summer .
Per their instructions, When I fill up, I just drive the car nicely for first 15 min and don’t sit at idle.
Do they have the secret sauce?
I know they work closely with Ford

He's talking about cars with boost. Not N/A cars.
How are you not running E all the time?? 93 just makes me sad now.

 

[sms2022]

He's talking about cars with boost. Not N/A cars.
How are you not running E all the time?? 93 just makes me sad now.

Off topic but what tire/spring specs are you running? Car looks great in your profile pic

 

[Magnetic Stang]

Off topic but what tire/spring specs are you running? Car looks great in your profile pic

Thanks. It's actually the stock setup with 20mm spacers on all 4 wheels with Michelin pilot sport 4s tires. The spacers seem to push the tire out enough that it fills in the wheel wells more.

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