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Discussion Starter #1
I really am wondering how bad E85 is for MPG compared to regular gas in a Pentastar 3.6 engine. Also wondering if a bad throttle position sensor can screw up MPG?
It's suspect because of pulsing idle when cold starting and it has trouble maintaining the proper speed when set in cruise. It will go 5 to 7 mph above where it is set and finally settle back to where it has been set. But what I can't handle is the 14 MPG city and highway driven mildly. I can't get above 20 mpg on the highway.
Signed WTF!o_O
 

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Do you have a Flexfuel car? If not you shouldn't be using E85 at all

On the bad running have you checked for codes?
 

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Discussion Starter #3
Yes it is flex fueI. My brother did that to a Northstar engine...Wasn't good.:eek: ( I'm hoping I'm not that dumb knock on wood).:rolleyes: I did get a misfire code about a month back on cylinder #5 switched spark plug and coil pack with #3 And it hasn't come back as of yet.
 

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Discussion Starter #4
I was going to put Ripp coil packs in it anyway and do new spark plugs but I would love to get to the bottom of this problem before I start throwing money at it.
 

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My Pentastar runs beautifully on E85. But the energy content/gal is way less than gasoline: about 30% less IIRC. I have never experienced a pulsing idle. No trouble maintaining speed on cruise control either. Perhaps you have some bad E85.
 

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Discussion Starter #10
30%,:oops: that's a lot. Even though E85 is cheap I have to wonder if regular is the better deal especially when driving highway miles. What kind of mileage do you get if you don't mind me asking.
 

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Yes, it is rather jaw-dropping. I have yet to find E85 less expensive than regular gasoline. I live in the Washington D.C. area.

My mileage on gasoline sometimes descends to 24 due to our horrible traffic. But if I can just cruise for hundreds of miles, I get well above 30mpg.
 

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With E85 you actually get less fuel to burn but you have the same # of gallons due to the E85 materiall taking unleaded fuel's place in the mix.

So this does have an effect on mileage.

I know a tuner close to me here who runs E85 in his HEMI but he tuned for it and said he had to as the engine ran like...er...let's say he just said "defecation" and leave it at that.
 

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Discussion Starter #13
Yes, it is rather jaw-dropping. I have yet to find E85 less expensive than regular gasoline. I live in the Washington D.C. area.

My mileage on gasoline sometimes descends to 24 due to our horrible traffic. But if I can just cruise for hundreds of miles, I get well above 30mpg.
E85 is quite a bit cheaper here in minnesota, I have been getting it for $1.94 and with the saver card $1.87. I think you might be right about the sub-par quality of the fuel. In fact it might be the source of it all. We have a station here called Minnoco that sells the cheapest E85 in the city. The first time I used it my car didn't want to start at all:mad: and I swore I would never use them again. I gave them one more shot thinking it may have been just a one time miss calculation on there part (and the price was so cheap that I wanted it to work). It never failed to start again so I have been using it regularly. Price doesn't equal performance, it very well may be my car trying to deal with using manure for fuel.:poop: Thanks guys for the feedback.Time to switch up and see.
 

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Discussion Starter #14
Wow what a dope I've been. I went for a long drive and ran out the last of the El Cheapo E85 and put some 89 octane in last night and just watched my mileage climb😊😁😆Yeah!!! I swear I could see my car smirking at me lol.
 
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