TIS
 

I recently paid for my 24 hour subscripton to the TIS, and discovered that the TIS doesn't really exist anymore. Now it is called ISTA (Integrated Service Technical Application). I really wasn't able to get much out of it and in order to "dig into it" you have to provide the last 7 digits of your VIN...kinda creepy.

Anyway, I was able to get several training manuals and SIB's that were imteresting.

One SIB that really struck me was SI B13 02 10. BMW evidently by either a special testing device, or by interrogating the computer can determine for gasoline engines, what octane level is in the fuel you have been using over the life of the vehicle, or for diesel, the cetane number of the fuel most often used.

Also, 51 is the cetane number most quoted in these "internal" documents as being required, but for most people is not readily available. It's really a catch-22 for most folks: you are not allowed to use diesel fuel additives but you must be using high cetane premium fuel or face having your poor quality of fuel being blamed down the line.:dunno:

Interesting.

There is a legal doctrine of 'warranty of merchantability', that some opine would require BMW to only sell cars that can be fueled by the fuels sold in the market.

They cannot sell cars that require special fuels into markets where those fuels are simply not sold...some may argue that 'they put it in the owners manual', but that may not protect them.

It will be interesting to see if this ever becomes an issue..BMW surely has used the "crappy american fuel" argument, but most people don't fight too hard....

A

You don't actually measure octane when you test a fuel, you measure knock and compare it to the knock from a reference fuel in a test engine under controlled conditions. BMW could easily determine how much the timing was being retarded in response to measured knock, but that wouldn't measure octane, because additional variables of altitude, ambient temperature, carbon buildup, etc, would all impact knock.

Correct about the carbon buildup; however, much of the other stuff is readily available to the computer, e.g., ambient temperature, altitude (air density/mass/pressure), etc.

Regarding the diesel, I am not sure how they would derive Cetane; however, if they could they would have a nice Catch-22:

(1) Sorry, the data shows you were not using the recommended 51 Cetane fuel, so you violated the warranty, or

(2) Sorry, the data shows you were using fuel with a Cetane rating of 51. Since such fuel is not in common use in the U.S., you must have been using a Cetane enhancing additive which is prohibited so you violated the warranty.


P.S. A Google search revealed this interesting link:

http://www.spiritpfc.com/shatox_octanemeterbrochure.pdf

The accuracy, if true, is rather surprising, at least to me.

While the other stuff is readily available, there is not a formula to convert a real world result to standard conditions using that data, since fuels do not respond linearly. Hence the need for a lab test engine.

What BMW could likely conclude from the data is that whatever the published AKI was of the fuel being used, a combination of altitude, temperature, engine condition, etc, was causing more retardation of the ignition timing than they would expect. That could help in the diagnosis of a complaint of reduced power or mileage, not a warranty situation though, unless the fuel was really bad (ie kerosene)

Interesting link on the dielectric analysis. Looks similar to what BMW is doing with onboard monitoring of oil additive levels.

Nice link! I wish I could get 51 cetane even with an additive. I've never measured it but the additive I am using in my other cars promises 6+ numbers. If I can get 46-47 reliably, I'll be a happy camper.

The faster my warranty is over the less I have to worry about my fate being decided by the Rota Fortunae of the dealer. Can't wait for 50,001 miles to come.