High gas prices..how about regular?

[binhly101]

Some may scoff at me...but I usually fill up when the tank still has 3/4 left and every other week, so paying the extra 20 cents from 87 is no biggie to me, I have figured it out to be like an extra 80 cents...I guess I will start skipping the caramel lattes at starbucks and just getting plain coffee...lol

[Buzzcut]

Originally Posted by JCL

Here is a thread on another member who was experimenting with E85. I posted BMW's paper on warnings re E85 in that thread.

http://www.xoutpost.com/bmw-sav-foru...l-mixture.html

It shouldn't be hard to say if there is a hit to mileage. It may be hard to measure the mileage accurately given other changes like weather, driving habits, etc, but the hit to mileage should be pretty close to 22%, eliminating all the other variables. That is just due to the 26% lower energy content of pure ethanol, and the resultant 22% lower energy content of E85, on a volumetric basis.

Yeah, Saab made the same disclaimers about fuel systems materials. It wasn't a problem in 15k miles. We will see with the X5.

With the Saab, there is a flex-fuel version that they sell in Sweden. the only part number that was different was the ECU. The entire fuel system was the same as the non-flex fuel version.

Regarding the hit to mileage, if you go to my blog I did a multiple regression of my mileage vs. ethanol content and average speed.

regression.JPG (image)

In statistical terms, ethanol content and average speed account for 50% of the variation in mileage. I think weather largely accounts for the rest. I really only use my car for commuting, and I drive the same route pretty much every day.

[LudjakR1]

I just tried regular the other day and car feels the same with 89. also burn the same amount of gas.

[JCL]

Originally Posted by Buzzcut

Yeah, Saab made the same disclaimers about fuel systems materials. It wasn't a problem in 15k miles. We will see with the X5.

With the Saab, there is a flex-fuel version that they sell in Sweden. the only part number that was different was the ECU. The entire fuel system was the same as the non-flex fuel version.

So are you going to modify your DME to accomodate the new stoichiometric ratio? 10:1 is quite a ways off 14.7:1

In the Ford models I was familiar with, it wasn't just the ECU change for the new air/fuel ratio, but also the elimination of a number of plastics in the fuel system. There is an easy way to find out if a BMW will have the same problems or not, just run it, but the consequences could be expensive.

[JCL]

Originally Posted by LudjakR1

I just tried regular the other day and car feels the same with 89. also burn the same amount of gas.

That is a good indication that the timing is not being retarded then, and that your engine doesn't require any higher AKI fuel than your local regular. Apart from the AKI, that regular may not have as many cleaning agents as a premium fuel, but a can of Tecron every six months could address that.

[LudjakR1]

Originally Posted by JCL

That is a good indication that the timing is not being retarded then, and that your engine doesn't require any higher AKI fuel than your local regular. Apart from the AKI, that regular may not have as many cleaning agents as a premium fuel, but a can of Tecron every six months could address that.

I still think that best is 92 93, from the old saying "you are what you eat",

[HPIA4v2]

Originally Posted by LudjakR1

I still think that best is 92 93, from the old saying "you are what you eat",

Isn't our rule of thumbs always when in doubt read the user manual (or in this case gas filler door?) And what does it say in there?

[LudjakR1]

Originally Posted by HPIA4v2

Isn't our rule of thumbs always when in doubt read the user manual (or in this case gas filler door?) And what does it say in there?

92 and up

[Buzzcut]

Originally Posted by JCL

So are you going to modify your DME to accomodate the new stoichiometric ratio? 10:1 is quite a ways off 14.7:1

In the Ford models I was familiar with, it wasn't just the ECU change for the new air/fuel ratio, but also the elimination of a number of plastics in the fuel system. There is an easy way to find out if a BMW will have the same problems or not, just run it, but the consequences could be expensive.

All modern fuel injection systems can accommodate some level of oxygenates. The whole "short term fuel trim" and "long term fuel trim" thing.

My experience with the Saab was that I could get to 40% ethanol before I got a check engine light. I have a Scangauge II, and I was monitoring fuel trim. It would allow LTFT of 25 before the check engine light went on.

Sadly, the Scangauge II does not show LTFT on the X5.

We shall see what the consequences are. I will be sure to let everyone know. I'm thinking of starting another blog about the experience. The only problem is that, with 96k miles, it wouldn't be unusual to have to replace an injector or a fuel pump, so it is going to be more difficult to say what caused the failure than it would be on a new car, as the Saab was.

[motordavid]

91...