Anyone get an occasional rough idle when the car is hot and on e85?

[Zinc03svt]

It could be the weather and E85. In colder temps I've found an E30-E40 mix makes the engine behave better. Are you on flex fuel tune or is it an E85 race tune? If on flex fuel I would add some 93 octane to it and see what happens.

It is straight up e85 tune. No flex. Getting E85 from a 6 month old station too. May grab a tester.

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[Andy13186]

Turns out my bank 1 sensor 1 o2 sensor was going bad, it threw a code eventually. I may stick with 93 since it seems like o2 sensors like to die on e85. p0030 was the code. Having the sensor replaced Monday.

 

[Zinc03svt]

Turns out my bank 1 sensor 1 o2 sensor was going bad, it threw a code eventually. I may stick with 93 since it seems like o2 sensors like to die on e85. p0030 was the code. Having the senor replaced Monday.

No kidding? I’m hoping it is just some winter to summer blend. O2’s are not cheap either.

 

[bootlegger]

Hey, did you ever sort out the idle stall issue? Mine has stalled now 2x in gear at a stop. WTF? Bad e85?

I am thinking of buying that kit that someone else installed on this forum to get a digital read of the EtOH content real time. I have noticed large variation in fuel economy and performance on each fillup. My last tank had almost no hard starts and I would get around 17mpg 60/40 (Hwy/City). This new tank is starting hard and I am getting about 16mpg. My exhaust always smells strong of alcohol as well, so I think I need to have PBD tweak the tune. It is hard to dial in when the E85 is so variable.

 

[bootlegger]

Turns out my bank 1 sensor 1 o2 sensor was going bad, it threw a code eventually. I may stick with 93 since it seems like o2 sensors like to die on e85. p0030 was the code. Having the sensor replaced Monday.

That shouldn't make the start rough. It could make the idle and normal running rough. BTW, I have had some slightly longer cranks since I first ran E85. I am probably at about 2k miles on nothing but E85 and not much has changed.

 

[Zinc03svt]

I am thinking of buying that kit that someone else installed on this forum to get a digital read of the EtOH content real time. I have noticed large variation in fuel economy and performance on each fillup. My last tank had almost no hard starts and I would get around 17mpg 60/40 (Hwy/City). This new tank is starting hard and I am getting about 16mpg. My exhaust always smells strong of alcohol as well, so I think I need to have PBD tweak the tune. It is hard to dial in when the E85 is so variable.

Yeah it is very possible (hopefully) it is just the corn. Car drives fine past idle which is strange. No codes as of yet. KAM reset is not helping. I cannot decide whether I should just try another e85 station first or just switch back to pump and see if it still does it...?

 

[brucelinc]

What is your AF/R reading at idle on corn?

 

[Zinc03svt]

What is your AF/R reading at idle on corn?

It is jumping from 9.0-10. Usually 9.4-9.6.

 

[brucelinc]

It is jumping from 9.0-10. Usually 9.4-9.6.

Is that a little rich...if you are on winter blend and not fully 85% E? I thought 9.8 was ideal if on full E85. Just asking....

 

[Zinc03svt]

Is that a little rich...if you are on winter blend and not fully 85% E? I thought 9.8 was ideal if on full E85. Just asking....

Yeah I think it may be just some bad fuel. It may be 9.7-9.8 when it is idling correctly. Cannot remember. The station says it is E70 minimum which I have a hard time believing. If the E content is lower then the car would be running rich.

 

[Deleted member 35786]

Occasionally my RPM will drop to like 450 a couple times and come close to stalling, usually when the car is warm then it goes back to normal idle. Happens on e85 but also happened once on the stock tune on 93 octane. Any ideas on what could cause that?

I am also in Florida but have never seen E85 at any of the pumps... Do you have a choice of which fuel to use?

 

[Andy13186]

I am also in Florida but have never seen E85 at any of the pumps... Do you have a choice of which fuel to use?

Only place I know of in the Tampa area are Thorntons

Pretty sure ill just run the 93 tune from now on though.

 

[Deleted member 35786]

Only place I know of in the Tampa area are Thorntons

Pretty sure ill just run the 93 tune from now on though.

Are you chosing E85? 99% of the pumps I see say "this fuel contains up to 10% ethanol"...

Unless your car is Flex Fuel certified then you should not be using it. Our mustangs are not designed for it, even states that in the owners manual.
https://afdc.energy.gov/fuels/ethanol_e85.html

 

[bootlegger]

Are you chosing E85? 99% of the pumps I see say "this fuel contains up to 10% ethanol"...

Unless your car is Flex Fuel certified then you should not be using it. Our mustangs are not designed for it, even states that in the owners manual.
https://afdc.energy.gov/fuels/ethanol_e85.html

Everyone in this thread has the car tuned specifically to run E85. Flex fuel cars have tunes to be able to adjust for 0-85% EtOH. The 2018 can run E85 with a simple tune, while 2015-2017 cars need a fuel system upgrade.

 

[Bluemustang]

Everyone in this thread has the car tuned specifically to run E85. Flex fuel cars have tunes to be able to adjust for 0-85% EtOH. The 2018 can run E85 with a simple tune, while 2015-2017 cars need a fuel system upgrade.

Nah. 15-17 cars don't need a fuel system upgrade. Tune and gtg.

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