Switching from e85 to flex tune issues

[DonnieO]

There is no fuel filter on the 5.0 coyote. Do what john lund says. You're on here asking questions when the tuner told you what to do.

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[Jhonda]

I searched before I posted this don’t know how I missed it. Thanks again

 

[Jhonda]

There is no fuel filter on the 5.0 coyote. Do what john lund says. You're on here asking questions when the tuner told you what to do.

I trust him but was wondering if anybody else had this issue. I didn’t want to end up at the pump with a car that want run. I was just trying to gather info

 

[Copperhead73]

I had the same issue coming off the E85R tune. It was explained to me that with straight E85 still in the tank and no new fuel added, a switch from E85R to flex will struggle to start.

The switch from E85R to flex with no change in fuel level leaves the car with a flex tune expecting to learn E content starting low and ramping up. However upon start the E content is much higher than the tune initially expects. After a few failed starts mine came to life and settled down without issue. Lund validated this when I reached out.

Sorry for the late reply, but just saw this. I imagine the issue is resolved since no follow-ups, but I wanted to echo LOL WUT.

I had the same problem. I was on the E85 R tune, ran E85 down low, switched to Flex Tune, then added 93. I had to start it probably a half-dozen times (only E85 in the tank) because it kept sputtering then dying. I had to feather the throttle very lightly to keep it running for a few minutes, then it straightened itself out rather suddenly. I went directly to the gas station and filled it up with 93. After I ran that tank through it, I switched back to the stock tune so I could run 87 until the weather warms up a little.

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