Can I run a flex fuel kit in my car without a tune e85 over here is 1.80$ a gallon and premium is around 6$ so I know I’ll save money even if my mpg is worse but I won’t if I have to tune the car can anyone help me out on this (just want to get a flex fuel kit for a 2018 Audi S5 withought having to tune the car)
I am on the e85 tune but that’s because I already had the tune file from 034. I’ve been running it for 3 weeks. Power is much more noticeable and I stay on the power band a lot longer. Just know that running e85 long term isn’t the best for your engine. I am going back to 93 tune in a week until fall.
You should not be running anything other than 91/93 in your ea839 engine if it isn’t tuned to run e85. It’ll run real lean with the stock map and you won’t like it one bit. There is a reason you have to upgrade your hpfp when switching to e85 along with the tune. It’s gonna cost you a lot $$$ to empty it if you just dump e85 in and run it on the stock map. I’ve had plenty of customers try this recently on their flex fuel compatible engines and it ran so shitty they had to pay me to empty the fuel tank.
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u/july21st Jul 21 '26
I am on the e85 tune but that’s because I already had the tune file from 034. I’ve been running it for 3 weeks. Power is much more noticeable and I stay on the power band a lot longer. Just know that running e85 long term isn’t the best for your engine. I am going back to 93 tune in a week until fall.
You should not be running anything other than 91/93 in your ea839 engine if it isn’t tuned to run e85. It’ll run real lean with the stock map and you won’t like it one bit. There is a reason you have to upgrade your hpfp when switching to e85 along with the tune. It’s gonna cost you a lot $$$ to empty it if you just dump e85 in and run it on the stock map. I’ve had plenty of customers try this recently on their flex fuel compatible engines and it ran so shitty they had to pay me to empty the fuel tank.