[535_BiTurbo]

Ive noticed that when I run an E20 or E30 mix on my 550i, the mid-range feels softer than when im on straight 93 without any e85 added in. I'm JB Stage 1 only and it feels much stronger with just 93 pump. Is it because the DME detunes itself on the E20/E30 mix?

Ive read that is does this on stock B58s, but does it do this on stock N63s as well.

2012 550i M sport - JB stage 1

[MattPro]

I have checked the fuel quality sensor's reading because I was curious what the E30 blend read as. With 13 gallons of 93 and 5 gallons of E85 (~E30) the fuel quality reading was still in the highest category for that tank of gas (did 2 tanks in a row and both were the same). So it shouldn't be detuning itself.

I will say that my car never feels as smooth with E85. Cold start is weird and the throttle response is a bit off. That's why I'm going with methanol injection.

For stage one you really shouldn't need E30 anyways, so you're fine to run 93.

[535_BiTurbo]

Originally Posted by MattPro

I have checked the fuel quality sensor's reading because I was curious what the E30 blend read as. With 13 gallons of 93 and 5 gallons of E85 (~E30) the fuel quality reading was still in the highest category for that tank of gas (did 2 tanks in a row and both were the same). So it shouldn't be detuning itself.

I will say that my car never feels as smooth with E85. Cold start is weird and the throttle response is a bit off. That's why I'm going with methanol injection.

For stage one you really shouldn't need E30 anyways, so you're fine to run 93.

What do you mean by throttle response being a bit off?

[MattPro]

Originally Posted by 535_BiTurbo

What do you mean by throttle response being a bit off?

Situations where the throttle changes, like if you were cruising and hit the gas quickly to accelerate. It feels not as responsive when on pure 93.

I bet that's because the acceleration enrichment tuning (when the throttle rapidly increases the EMS needs to inject additional fuel on top of the load fueling, all engines are this way) is thrown off with the additional fuel demands with the E85 blend.

[535_BiTurbo]

Originally Posted by MattPro

Situations where the throttle changes, like if you were cruising and hit the gas quickly to accelerate. It feels not as responsive when on pure 93.

I bet that's because the acceleration enrichment tuning (when the throttle rapidly increases the EMS needs to inject additional fuel on top of the load fueling, all engines are this way) is thrown off with the additional fuel demands with the E85 blend.

Yes, I've noticed that as well.

[550Reasons]

you dont have the JB4 beta with the flex fuel cables right ?
because without it E85 mix does nothing really

[MattPro]

Originally Posted by 550Reasons

you dont have the JB4 beta with the flex fuel cables right ?
because without it E85 mix does nothing really

Correct, I think that's still limited to the n54 guys.

But E85 mix does do quite a bit on our cars. When you target an E30 blend of fuel you are slightly north of 95 octane. Since our JB4 doesn't control timing in any way, the DME tries to run full timing and dials it back with use of the knock sensors. Terry says anyone running map 7 should either be on race fuel, E30 blend, or meth for safety due to the increased boost levels increasing the risk of knock. The E30 blend helps make more power safely for two reason, one is the increased octane, and one is the increased fuel volume entering the cylinder to cool down the cylinder temps (both of which help mitigate the risk of knock).

[535_BiTurbo]

Originally Posted by MattPro

Correct, I think that's still limited to the n54 guys.

But E85 mix does do quite a bit on our cars. When you target an E30 blend of fuel you are slightly north of 95 octane. Since our JB4 doesn't control timing in any way, the DME tries to run full timing and dials it back with use of the knock sensors. Terry says anyone running map 7 should either be on race fuel, E30 blend, or meth for safety due to the increased boost levels increasing the risk of knock. The E30 blend helps make more power safely for two reason, one is the increased octane, and one is the increased fuel volume entering the cylinder to cool down the cylinder temps (both of which help mitigate the risk of knock).