System too lean

[526 HRSE]

So with my mods, i feel like i dodged a bullet. I changed throttle bodies from 87mm to 91mm. I changed CAI to a JLT (no tune required). I also have Proflex for e85.

Car runs great and has never thrown a code. Today i was checking the obd2 for a possible alternator issue and found the codes on the scanner. p0171 and p0174 LTFT on both banks is 20% at idle.

I recently ran some fuel cleaner through the system but i don't believe that to be the issue since it's both banks. Although, i did have an injector get a little louder for a day or so.

With my setup, you can definitely hear a gasp for air once i hit the throttle but it's very responsive and very fast.

What do smarter people than me think? I don't want to have to tune this thing.

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[SheepDog]

Put your factory intake back on and see if the fuel trims drop back down to an acceptable delta (+/- 10% or less), then you will know it's the JLT intake or not. You aren't gaining any performance from it anyway over the GT350 one. It may also be a result of the larger throttle body (which would probably also require a tune for best results) but you will know for sure when you put the OEM intake back on and test.

Have you been running E85, or are the trims lean with gasoline too?

 

[junits15]

I’d bet it’s your proflex flex fuel device. Try removing it and seeing if this issue takes care of itself

 

[galaxy]

No expert, but I did a ton of homework on intakes when preparing for my tune. Talked to several reputable tuners, etc. the normal JLT intake hardly does anything for this car, can’t imagine a “no tune” intake does anything at all.

 

[526 HRSE]

The JLT is definitely bigger and smoother than the stock air intake. It may not make a difference on the 87mm throttle body, but it seems like the stock one will bottle neck the 91.

I mean, i know i'm getting extra air, now i'm thinking i want the extra fuel.

As i've said before, these mods are much faster than stock. Definitely not removing the Proflex.

Sheepdog, i've been running mostly e85 with the new TB. I ran a mixture most of the time prior to the tb, but with it, the e85 is much more alive.

 

[Mjc1241]

Interested to see if the trims are on 93 as well 526 HRSE.

 

[honeybadger]

The JLT is definitely bigger and smoother than the stock air intake. It may not make a difference on the 87mm throttle body, but it seems like the stock one will bottle neck the 91.

I mean, i know i'm getting extra air, now i'm thinking i want the extra fuel.

As i've said before, these mods are much faster than stock. Definitely not removing the Proflex.

Sheepdog, i've been running mostly e85 with the new TB. I ran a mixture most of the time prior to the tb, but with it, the e85 is much more alive.

Sounds like you answered your own question - if you're getting more air and the stock ECU can't compensate, it's going to throw codes. Pull the intake and TB and see if it still has an issue. That'll let you know.

That said - I'm personally not a fan of something like the proflex as it leaves the stock ECU in the dark because it just multiplies the factory injectors based on the ethanol content it sees. You're not even taking advantage of different timing tables--you're leaving HP on the table big time.

 

[junits15]

The JLT is definitely bigger and smoother than the stock air intake. It may not make a difference on the 87mm throttle body, but it seems like the stock one will bottle neck the 91.

I mean, i know i'm getting extra air, now i'm thinking i want the extra fuel.

As i've said before, these mods are much faster than stock. Definitely not removing the Proflex.

Sheepdog, i've been running mostly e85 with the new TB. I ran a mixture most of the time prior to the tb, but with it, the e85 is much more alive.

It’s unlikely the car is much faster at all, I’ll be honest you’ve spent all this money on these mods why wouldn’t you just get a tune and get some actual power out of the car?

the proflex commander does not add timing, so you are not getting most of the e85 benefit. It also breaks the feedback loop between the injectors and the wide bands. This is why I suggested removing it, because the control system is effectively not working as designed. So you need to see if that’s the issue or not.

Any small error can cause this type of behavior because the proflex just tells the ECU that everything is good all the time.

You can leave it on, but if it’s the problem you won’t be able to work around it by playing with the intakes.

 

[526 HRSE]

Interested to see if the trims are on 93 as well 526 HRSE.

I'll check next fill-up

 

[SheepDog]

Any small error can cause this type of behavior because the proflex just tells the ECU that everything is good all the time.

Sounds like a good way to melt a piston.

 

[526 HRSE]

It’s unlikely the car is much faster at all, I’ll be honest you’ve spent all this money on these mods why wouldn’t you just get a tune and get some actual power out of the car?

the proflex commander does not add timing, so you are not getting most of the e85 benefit. It also breaks the feedback loop between the injectors and the wide bands. This is why I suggested removing it, because the control system is effectively not working as designed. So you need to see if that’s the issue or not.

Any small error can cause this type of behavior because the proflex just tells the ECU that everything is good all the time.

You can leave it on, but if it’s the problem you won’t be able to work around it by playing with the intakes.

I don't think I had the issue until adding the throttle body and intake. Had the pro flex for a couple years by itself.

As I said, there's no dash cel, just in the OBD2.

Butt dyno says it's faster or at least a lot more torque.

 

[SheepDog]

I don't think I had the issue until adding the throttle body and intake. Had the pro flex for a couple years by itself.

As I said, there's no dash cel, just in the OBD2.

Butt dyno says it's faster or at least a lot more torque.

Just change one thing at a time until you figure out what is causing this.

Did you periodically pull the codes when you only had the flex fuel gizmo, to know for sure that it wasn't running lean prior to the intake and throttle body?

Maybe start by just filling the tank with gasoline. If the trims come down, you probably know that it is the Proflex. If not, I would still be looking at the intake.

Running lean does make more power (until it doesn't), which is why it feels faster, as well as the knock sensors giving you a bit more timing than you would get on pump gas.

 

[526 HRSE]

Sounds like you answered your own question - if you're getting more air and the stock ECU can't compensate, it's going to throw codes. Pull the intake and TB and see if it still has an issue. That'll let you know.

That said - I'm personally not a fan of something like the proflex as it leaves the stock ECU in the dark because it just multiplies the factory injectors based on the ethanol content it sees. You're not even taking advantage of different timing tables--you're leaving HP on the table big time.

As mentioned above, I am going to see if this is an e85 reaction. I know the profile itself isn't causing any issues since I had it on the car for two years prior to adding tb. It's understandable that I'm now getting more air than fuel, but is it within specs since it isn't throwing a dash cel?

Do you think bad e85 could cause this condition?

 

[honeybadger]

I don't think I had the issue until adding the throttle body and intake. Had the pro flex for a couple years by itself.

As I said, there's no dash cel, just in the OBD2.

Butt dyno says it's faster or at least a lot more torque.

Actual dyno will say otherwise - you're not getting any performance benefits from E85 without a tune. The OEM ecu is not programmed to take advantage of it even if it knew it was running ethanol - which the proflex doesn't fix. You're not going to get more power without adjusting the the fueling and ignition tables. If there was power to be had with just fuel, Ford would've posted a 100 octane power figure. But 100 octane doesn't improve power without a tune, just reduces likelihood of pre-detonation

 

[526 HRSE]

If I were to break down and get a tune, should I go larger injectors?

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