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

[Andy13186]

At around 15:12 in this log the stumble happens. https://www.dropbox.com/s/ne5xrpwj4g1uv7i/log0050.csv?dl=0 It may have happened a few other times in this log I am not sure this was from a few months ago.

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[Andy13186]

Still have no check engine light, but I am still getting a really rough idle randomly while stopped while the car is warm. It goes rough for a bit then recovers and is fine for a while. I am considering getting different spark plugs just to see if that helps. I dont know though, it seems more like a sensor but it makes no sense since no light is coming on.

It also makes no sense since I had the sensor replaced and the issue still was happening on pure 93 octane and the stock tune.

I wonder if a fuel injector is partially clogged or something or somehow a plug is not happy, but the car runs and idles great most of the time so, to me it seems like some sensor issue but I cant figure it out. I wonder if a catch can could cause some type of intermittent flow issue? The can is not full I empty it often.

Anyone have any ideas? Also, what type of spark plugs would be best for e85 on a NA e85 tune only car?

 

[Zinc03svt]

Still have no check engine light, but I am still getting a really rough idle randomly while stopped while the car is warm. It goes rough for a bit then recovers and is fine for a while. I am considering getting different spark plugs just to see if that helps. I dont know though, it seems more like a sensor but it makes no sense since no light is coming on.

It also makes no sense since I had the sensor replaced and the issue still was happening on pure 93 octane and the stock tune.

I wonder if a fuel injector is partially clogged or something or somehow a plug is not happy, but the car runs and idles great most of the time so, to me it seems like some sensor issue but I cant figure it out. I wonder if a catch can could cause some type of intermittent flow issue? The can is not full I empty it often.

Anyone have any ideas? Also, what type of spark plugs would be best for e85 on a NA e85 tune only car?

That is crazy. I was running breathers for 4500 miles before my issues started. Doubt the catch made any difference. I would also think a spark plug issue would not be intermittent. Sooo...after you had all this stuff replaced at the dealer are they not seeing this continued idle issue on their diagnostic equipment? It might be bad throttlebody?

They saw my cam phasers drop to zero degrees while at idle. If mine is not fixed it is staying at the dealer until they figure it out.

 

[Zinc03svt]

I have noticed my car does not have any idle issues when battery has been charged and on tender. Today the voltage never moved off 14.6 volts. Ran perfect too. It is when the voltage is jumping around is when I see these idle variations. Fyi.

 

[Andy13186]

I have noticed my car does not have any idle issues when battery has been charged and on tender. Today the voltage never moved off 14.6 volts. Ran perfect too. It is when the voltage is jumping around is when I see these idle variations. Fyi.

Is this solution still working for you? Ive had some random strings of good days with no issues at all, now some bad days where it will go rough like 5 times in 5 minutes.

 

[Zinc03svt]

Is this solution still working for you? Ive had some random strings of good days with no issues at all, now some bad days where it will go rough like 5 times in 5 minutes.

I unplugged my battery management system (search for thread on it) last night. It was holding 14.3-14.4 volts. Also my 8 amp charger was showing bad battery so I will try to get into Ford (hopefully this time) to get a new one under warranty. It is running better than it did pre cam phasers. Had maybe one stumble when battery was not on tender and voltage was jumping around 12.6-14.7. ?? Weird shit.

 

[Andy13186]

I unplugged my battery management system (search for thread on it) last night. It was holding 14.3-14.4 volts. Also my 8 amp charger was showing bad battery so I will try to get into Ford (hopefully this time) to get a new one under warranty. It is running better than it did pre cam phasers. Had maybe one stumble when battery was not on tender and voltage was jumping around 12.6-14.7. ?? Weird shit.

Voltage jumps, RPM jumps, I think the AFR jumps all at these times. I still kind of think its a dying or dead sensor that isnt sending out a code

 

[Zinc03svt]

Voltage jumps, RPM jumps, I think the AFR jumps all at these times. I still kind of think its a dying or dead sensor that isnt sending out a code

I had my tuner bump up my idle on E85. Have you tried that?

 

[Andy13186]

I had my tuner bump up my idle on E85. Have you tried that?

yea mines at 750 currently. Hasnt actually stalled since but it still has gone rough.

 

[Zinc03svt]

yea mines at 750 currently. Hasnt actually stalled since but it still has gone rough.

I will keep you posted on battery mgt unplugged. Fuel vapor sensor still an option?

 

[Diocletian]

Ah yes, I've had the same idle surging issues on E85 flex and race tunes. Only happens at idle or very low speeds when I'm not on throttle. Tapping the gas stops the issue, and the car has never stalled, this happens maybe 25% of the time. I have sent logs to Lund, they say trims were fine and that my O2 sensor was bad, my car was brand new and only had 3600 miles on it.

Just like the other guy in this thread, I took it to Ford, they tested the sensor and did not find an issue. Also, on the E85 race/flex tunes I have thrown P0300s on start up. I notice the surging happens when warming up, or on a warm start.

It freaked me out too much to keep running E85 because I thought I was destroying my engine. I ran 8 or so full tanks of e85 from a brand new Mobil gas station too. When I switch to my stock tune or 93 tune the problems go away 100%. Weird stuff

Upon suggestion of this thread I ordered an e85 tester, we'll see what I find. Pisses me off though, I paid money for a tune I can't use. I also sent a message to Palm Beach Dyno, considering having them having a hand at it, apparently they have great results on E85.

 

[Zinc03svt]

I do not think it has to do with the tuning. Andy and mine did the same rough idle/stall on stock tune. I have since kept my battery on charger/tender and unplugged my battery management system and car is running near perfect. Idle issues always started when my voltage started going up & down.

Agreed, it is hard to track down these silly issues sometimes. But, an occasional idle surge is not that big of deal in the end imo. Car rips!

 

[Diocletian]

So on recommendation of a local here who is also running E85 on his 2018 GT I joined a E85 group that goes around and constantly verifies the fuel at the stations in the area. I went to a verified good E85 station, I had about 1.5 gallons of 93 left when I filled up, drove around about 20-ish miles and started to notice while the car was still learning the E85 that it was performing WORLDS better than when I filled up at the E85 station near me. Pretty sure I got another 10 or so miles to fully clear out the 93 but I'm happy so far. Man when it's in park trying to learn the fuel it does sounds kinda like shit(occasionally RPMs dip really low). I would've kept driving(just hit 8k miles after 14 months of ownership lol) but it was about to pour down rain. Hope this gets rid of some of the issues I had on E85 before, I definitely had a smile ear to ear while ripping it around lol.

 

[Diocletian]

I do not think it has to do with the tuning. Andy and mine did the same rough idle/stall on stock tune. I have since kept my battery on charger/tender and unplugged my battery management system and car is running near perfect. Idle issues always started when my voltage started going up & down.

Agreed, it is hard to track down these silly issues sometimes. But, an occasional idle surge is not that big of deal in the end imo. Car rips!

I checked my voltage and it's solid at 14v with no dips, it didn't seem to correlate to the dips in RPM, what is this battery management system you speak of? I only drive this car 1 day a week but if it helps you out I could give it a shot

 

[Zinc03svt]

I checked my voltage and it's solid at 14v with no dips, it didn't seem to correlate to the dips in RPM, what is this battery management system you speak of? I only drive this car 1 day a week but if it helps you out I could give it a shot

Do not know if it is any correlation w/ bad idle yet long term.

https://www.mustang6g.com/forums/threads/battery-management-system-reset.106897/

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