2023 GT E85 Flex Tune Backfire/Stumble on accel.

[Berserk]

Hey Guys, I was wondering if anyone has had this experience before.

2023 GT, PB Dyno E85 Flex tune on currently. Full E85, car has had full E85 for weeks now. H pipe, and I deleted the carbon filter. I let the car warm up properly and the HP Tuning device does not pick up any codes at all. I have not reverted back to 91 to test or to stock to see if I stop noticing this. I think I'll put it on the proper E85 tune tomorrow and see if anything changes.

However, Lets say I'm cruising on the highway 4th gear at 3,500 RPM and I just snap press the throttle maybe an inch down. I notice the car seems to like hiccup or backfire, then goes. There is like this weird slight delay where I can hear it rev up then i feel like there is little to no movement then it kicks / bumps a bit and then goes like it's 100% healthy after that. It's very strange. I kind of expect the car to backfire a bit if I snap the throttle and let go, but it does this odd behavior when I snap the throttle and even keep it pressed down. I don't really know how to describe it well but in my head it's like. Snap pedal, rev, delay, go. I have some really bad memories / horror stories from my old EcoBoost so anything that feels slightly weird or off freaks me out. But I do not think I'm being paranoid that it is a bit off. I need to log the car and do tune revisions with PB Dyno but they never really asked me to and didn't seem super inclined to when I mentioned it in passing. Anyhow, was wondering if anyone had experienced this before or know what it might be?

Thanks.

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[gcadorette13]

I would send them logs and if they don't help you then I would switch tuners. It really sucks cause you've already spent the money. They dropped the ball with me pretty hard so I dumped them and haven't looked back since.

 

[ZXMustang]

As said, nobody is going to know anything until you get the behavior in a log. Hook up the laptop with HPT and make sure you are running their channel config, and get that stumble/backfire on log. Then send it in. They should be able to see exactly what you are feeling from the log. Then correct accordingly.

 

[AZ18yote]

Another member had this info post carbon trap removal:

Just thought I would share a little info on an issue I ran into while getting E85 tuned by @Wengerd Performance. To be very clear, this issue had nothing to do with his tune, and Darryl has been more than helpful, responsive, and the car is transformed on his E85 calibration. Anyone on the fence about going with Wengerd and E85- Just do it.

The day I brought my Mach 1 Home, mod #1 was to remove the carbon trap/restrictor from the intake to get my 10HP back that Ford stole from me. A simple 10-15 minute job, and put the intake back on the car. I drove it this way for about 2 weeks before getting the tune, and never noticed any change in performance but wasn't experiencing any loss of power, drivability issues or anything like that. I just figured, meh 10 HP wasn't going to make a noticeable difference anyway. (At this point I did not have any way to log, as I was still waiting for my RTD+ to show up).

As it turns out, after working with Wengerd it became apparent that something was amiss. The car would not idle correctly. When coming to a stop, any time I put the clutch in the RPM's would climb to about 2500 and then after about 5 seconds return to normal idle speed. The behavior was mimicking a vacuum leak or maybe a bad Idle Air control motor. After sending some logs Mr. Wengerd noticed that my fuel trims were hovering around +20%. So, either I had flashed a gas tune with E85 in the tank, or I had a leak somewhere (or so we thought)

Long story short- If you want to remove the carbon trap from the intake, you need to separate the filter portion from the fluted section, and then put the fluted section back in. The issue here was that by removing the entire assembly, this increased the inner diameter of the intake tube, which of course threw off the MAF readings. After thinking about what I had done, and scouring over the intake piping, throttle body, intake manifold etc. for leaks I had a light bulb moment and realized what had happened. Pics attached of the pieces.

If you leave the fluted sleeve section out, your gonna have a bad time.

simply separate the round filter potion from the sleeve, then put the sleeve back in. You can see where it fits around the MAF Sensor, and clearly reduces the size of the intake tube. Perhaps this issue has already been discussed, but just thought I would share incase anyone else wanted to do this.

 

[PC_GUARD]

Sounds like an air or maf table issue. If you have an air leak post maf it may not code.. purely guessing your issue

 

[Berserk]

Another member had this info post carbon trap removal:

I'm curious if this would affect the 5.0 in the same way? The Mach 1 and the 5.0 are quite different in regards to the intake anyhow. I pretty much only deleted the carbon filter, then this small plastic cage that it sits within. I sent a log to my tuner today and asked if removing the filter and the small plastic cage would cause any harm.

As said, nobody is going to know anything until you get the behavior in a log. Hook up the laptop with HPT and make sure you are running their channel config, and get that stumble/backfire on log. Then send it in. They should be able to see exactly what you are feeling from the log. Then correct accordingly.

Did just that today.

 

[junits15]

Flex tunes aren't perfect, you can try performing a KAM reset and letting the fuel re-learn. They can (and do) get stuck at the wrong ethanol value which will effect fueling.

Check your long term fuel trims if you can, if you have a compatible device you can also try to see what the learned ethanol percentage is.

I don't like fords inferred alcohol content system, its not well suited to a performance application imo.

 

[K4fxd]

If your tune was before you removed the carbon trap tube that is your issue. Should show up on logs.

 

[ZXMustang]

Flex tunes aren't perfect, you can try performing a KAM reset and letting the fuel re-learn. They can (and do) get stuck at the wrong ethanol value which will effect fueling.

Check your long term fuel trims if you can, if you have a compatible device you can also try to see what the learned ethanol percentage is.

I don't like fords inferred alcohol content system, its not well suited to a performance application imo.

This. I always log my car at fuel changes. And because it takes a while for the fuel to get through the fuel system, the fuel trims can mature before the car sees the octane change. And then it will be running either plus or minus a lot on the long term fuel trims. That happens to my 22GT every time. I have to flash a different rev tune once I know the higher or lower E content has gotten through the fuel system. That will trigger a relearn of the fuel trims. And I found that letting the car learn at idle is about the cleanest way to get consistent near zero long and short term fuel trims once they mature.

I been going round and round with my guy with these stupid flex tunes, and I just gave up. Disabled flex, put the car at 10.5 stoich and just moved on with my day. Car runs flawlessly now and its happy on full E. My advice, do the same. And when you think you might run low or out, just flash a flex tune on it at the station or a normal 91/93 tune and run that until you can get E again.

These cars are not made to do this, even though technically they can. All tuners have done is copied the settings from the F150 that was made to run flex. And it runs like shit at best in the coyote. Too bad we cant run a real sensor like in the GM stuff.

 

[junits15]

This. I always log my car at fuel changes. And because it takes a while for the fuel to get through the fuel system, the fuel trims can mature before the car sees the octane change. And then it will be running either plus or minus a lot on the long term fuel trims. That happens to my 22GT every time. I have to flash a different rev tune once I know the higher or lower E content has gotten through the fuel system. That will trigger a relearn of the fuel trims. And I found that letting the car learn at idle is about the cleanest way to get consistent near zero long and short term fuel trims once they mature.

I been going round and round with my guy with these stupid flex tunes, and I just gave up. Disabled flex, put the car at 10.5 stoich and just moved on with my day. Car runs flawlessly now and its happy on full E. My advice, do the same. And when you think you might run low or out, just flash a flex tune on it at the station or a normal 91/93 tune and run that until you can get E again.

These cars are not made to do this, even though technically they can. All tuners have done is copied the settings from the F150 that was made to run flex. And it runs like shit at best in the coyote. Too bad we cant run a real sensor like in the GM stuff.

I agree with everything you said lol

You're completely right its just copy pasted from the F150 and it doesn't work right most of the time. I did a bunch of testing on my own, I enabled the flex logic to see how it works left all the base and MBT timing stock.

I can recall a time where the car was at 10%, I filled ~40% of the tank with e85 and it "matured" at 12%. KAM reset and bam learned to 30%, that's a 28% error. Totally unacceptable.
Then I drove around until the tank was near 0 and filled with 93 octane 10% ethanol, calculated E% should have been 15% the car stopped learning at 22% again, not good enough.
Final nail in the coffin was when the car had learned down to 11%, I filled with 93 octane 10% ethanol and the damn thing learned up to 20% while idling and matured soon after. Fuel trims were lower than -15% total. I gave up at that point. There isn't enough adjustability given to us to make the ethanol system accurate.

I'm sure most tuners change this but in stock form, the F150 is set up so that anything below 27% ethanol is treated as 10% ethanol, and anything above 57% ethanol is treated as 85% ethanol. That gives an idea of what this stock flex logic is intended to do.

If someone just wants a flex fuel car with no additional power over stock it works great for that, the inaccuracies are absorbed by the long term fuel trims. There would be no significant timing changes so no real risk from getting "stuck" at the wrong value. As far as using it to actually add power based on ethanol content, idk it makes me nervous. Just like you said, a real sensor would be much better.

EDIT: I should note I don't think that its impossible to get accurate ethanol percentages from an inferred ethanol content system. I just think that the mustang's was never set up for performance applications and as a result it doesn't give very precise values all the time. It feels like ford designed it for a purpose and nothing more. If more of that feedback loop was made available to the tuning community I think it definitely could be made better and useable.

Anyway I'm sorry I got us off topic

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