[Indyeah]

Jesus this forum sometimes... The length people go to in order to save a couple bucks. Just use what the manufacturer recommends and stop wasting your time agonizing over using a different fuel.

[Indyeah]

Originally Posted by usshelena725

Again...

I dont understand your point. I didn't say use 91. I said use what your car is supposed to use and move on.

[Needbmwpartzz]

Can I put detergent instead of injector cleaner.......seems to clean crud off my dishes pretty good

[hassmaschine]

Originally Posted by gbalthrop

To try to rationalize some of the discrepancies in this thread:
1) As stated above, RON is an octane rating used in Europe and much of the ROW (Rest of World), BUT, AKI is the octane rating used in the US and is the octane number appearing on the US gas pump (and also the fuel door of your US vehicle).

2) 87 AKI = 91 RON; 87 AKI (US "Regular" unleaded gas with 10% Ethanol) is the same actual octane as 91 RON, just a Different Rating system & number. See "Examples" Table in following Wiki:
https://en.wikipedia.org/wiki/Octane_rating

3) 91 AKI fuel is "highly recommended" but the MINIMUM AKI Rating is 87 for non-turbo and 89 for turbo, per the Owner's Manual:

"Required fuel

Super Premium Gasoline/AKI 91
This gasoline is highly recommended.
However, you may also use gasoline with less
AKI. The minimum AKI Rating is:
> 323i, 328i/xi: 87
> 335i: 89."

Unfortunately BMW has NOT chosen to give any clues as to WHY "Super Premium Gasoline/ AKI 91 is highly recommended." BMW or its dealers have done some some weird things to further confuse the issue. My Fuel Filler Flap has a sticker on the inside that says: "minimum octane rating (91 AKI) see Owner's Manual for details."

I have run my N52KP engine on 87 AKI since I bought it and it has performed flawlessly.

QUESTION: WOULD THE IGNITION BE MORE ADVANCED IF USE PREMIUM?

I hope we can all agree that our engines (1) have knock sensors; that (2) ignition timing is automatically retarded to prevent detonation/ knock, in certain situations, and within certain limitations; that (3) all other things begin equal (which they seldom are ;-) more power is produced in high-load, high-RPM (WOT acceleration) when ignition is more advanced; and that (4) Ignition Timing advance of #1 cylinder (Zündzeitpunkt Zylinder 1) can be read in Real Time (Parameter or Status) using INPA or other capable scan tool.

What I have NOT seen in this thread is any discussion of the the DME strategy or Algorithms for advancing/retarding spark. Also, I have NOT seen any suggestion anywhere of any alternative/ multiple "Mapped" DME strategies that can be selected determined on octane rating of the fuel that is being used.

Unless there is a way to "code" the DME to run a "timing" Map (already installed in the DME) with higher advance curve when running a higher octane fuel, then POSSIBLE DME strategies that occur to me, that allow a higher octane fuel to give better WOT (Wide-Open-Throttle) acceleration are (NOTE, these are simply SWAGS, and NOT actual knowledge):
1) There are multiple advance curve Maps in the DME, and at engine start, the DME runs the highest advance Map as default until the knock sensor signal causes it to "downshift" to a lower advance curve;
2) In certain situations, such as high-load or high-RPM, the ignition advances until knock sensor signal, and then backs off;
3) There are TWO Maps, high and low, that the DME selects one or the other depending on some algorithm which might include such inputs as: last used, knock sensor input, engine temp, load, RPM, etc.

Point is, these are all guesses, and there are other possibilities NOT included.

If there are multiple maps, or if the strategy is advance until knock, then even higher octane fuel (AvGas) MIGHT produce higher performance.

Bentley is NOT terribly helpful here, but it does state (p. 120-7):

"A knock sensor is a piezoelectric microphone
tuned to the frequencies of engine knock or detonation. If engine
knock is detected, ignition spark is retarded by the ECM. If a fault
with the knock sensor is detected the malfunction indicator light
(MIL) is illuminated"

It should be noted that Bentley suggests NO warning light, or Fault Code, will be lit on dash, or saved in DME memory, if a knock is detected, or ignition is retarded; HOWEVER a Warning Light WILL light and a Fault Code WILL be saved in DME IF there is a fault detected in the Knock Sensor circuit (wiring, connector or sensor itself).

ANYONE actually know what strategy is used in the MSV80, MSD80 or other DMEs used with N51, N52, N52KP, N54 & N55 engines? If so, please cite any authority for such strategy being used.

ANYONE actually DONE any tests to see if there is greater advance with Premium than with Regular, and if so, how many degrees, and at what parameters, such as Load & RPM?

ANYONE know of any way to be able to read knock sensor signal in real time (Status/Live Data) or of any fault saved in memory if it detected knock, so we could determine if the timing is being retarded or knock is being detected?

George

These are absolutely not "guesses". I have spent hundreds of hours looking through the disassembly code on these engines.

There's an internal fuel quality detection algorithm - it determines which ignition maps are used (based on knock sensor data mostly). The N52 has KF_DZW_TD98, (98 RON octane), KF_ZW_VT98, and KF_ZW_VT_VL98. There are also a set of maps for "low" octane. So if you never put premium fuel, it will use the low octane maps. The other N5x engines are similar.

Put simply, it will make less power. It won't blow up. Use whatever fuel you want.

you don't "code" anything in the DME - but you could edit the high octane maps to use a higher octane fuel (such as 100 octane race gas). Whether that would actually help anything is another discussion.

[ahlbe1cl]

Originally Posted by usshelena725

Again...

I have a 2011 with N51. It clearly states 91 Octane minimum on the fuel door.

What engine is this? It was mentioned to be a 2013, so that's a cross over year.

My wife drives a X3 35i, that recommends 89 minimum.

I feel no reason why a lower compression NA motor would need more than a higher compression forced induction motor, but I think the OP is simply quoting what his fuel door is recommending and asking the question. I wonder this as well.

[E9TOU]

Is it really worth the savings?

The current US AAA national averages:
87 cost $2.85/gal x 13 gallons = $37.05
91 cost $3.40/gal x 13 gallons = $44.20
Savings of 87 over 91 = $7.15 per fill up
Assuming you fill up once a week, there are 52 weeks/year, which turns out to a savings of $371.80

Generally speaking, the cost of premium gas is much closer to regular in most locations so I'm not sure why the national averages are so far off. I personally don't think the drop in performance and efficiency is worth it.

[gbalthrop]

Originally Posted by hassmaschine

...There's an internal fuel quality detection algorithm - it determines which ignition maps are used (based on knock sensor data mostly). The N52 has KF_DZW_TD98, (98 RON octane), KF_ZW_VT98, and KF_ZW_VT_VL98. There are also a set of maps for "low" octane. So if you never put premium fuel, it will use the low octane maps. The other N5x engines are similar.

Thanks for that. As I understand the above, there are 3 High Octane maps and I presume 2 or 3 Low Octane maps. Do you know how often/when the DME determines if it should go to a Higher Octane map in the absence of any knock sensor signal.

I have been running (happily ;-) on 87 AKI. If I wanted to see what I was missing, and filled up a near-empty tank with 91 AKI (or better), how long would it take the "detection algorithm" to go to the highest advance map for that octane?

Is there anything similar to a battery "histogramm" or any need to delete adaptations, or anything like that? In other words, if it has been running in a certain map or map range/group, how/when will it adapt to higher octane fuel?

Finally, is there any Status/Parameter readout you know of to be able to tell in real time what Ignition Timing Map is being used (Live Data)?

Thanks,
George

[hassmaschine]

Originally Posted by gbalthrop

Thanks for that. As I understand the above, there are 3 High Octane maps and I presume 2 or 3 Low Octane maps. Do you know how often/when the DME determines if it should go to a Higher Octane map in the absence of any knock sensor signal.

I have been running (happily ;-) on 87 AKI. If I wanted to see what I was missing, and filled up a near-empty tank with 91 AKI (or better), how long would it take the "detection algorithm" to go to the highest advance map for that octane?

Is there anything similar to a battery "histogramm" or any need to delete adaptations, or anything like that? In other words, if it has been running in a certain map or map range/group, how/when will it adapt to higher octane fuel?

Finally, is there any Status/Parameter readout you know of to be able to tell in real time what Ignition Timing Map is being used (Live Data)?

Thanks,
George

There's way more than those - but VL is the "full throttle" map (Vollast). Then there are VL throttled (makes sense right? lol), part load, and part load throttled - which just means the throttle plate could be partially closed. Then there are limp maps, idle maps, cat heating maps, etc. etc. I think there's something like 20 or 30 different ignition maps. But if you're looking at what map it would use with premium fuel at full load it would be KF_ZW_VT_VL98.

yes, there are stored knock adaptations, and yes, if you ran for a long time with 87, resetting them after you fill up with premium is probably a good idea.

There are various ignition angle values that can be logged, yes.

[tlow98]

Originally Posted by E9TOU

Is it really worth the savings?

The current US AAA national averages:
87 cost $2.85/gal x 13 gallons = $37.05
91 cost $3.40/gal x 13 gallons = $44.20
Savings of 87 over 91 = $7.15 per fill up
Assuming you fill up once a week, there are 52 weeks/year, which turns out to a savings of $371.80

Generally speaking, the cost of premium gas is much closer to regular in most locations so I'm not sure why the national averages are so far off. I personally don't think the drop in performance and efficiency is worth it.

The other side of this equation is how often do you actually use full power. If you are only at the RPM that produces max power 16% (7.15/44.2) (or less time then technically what are you not missing much use of that extra power.

I can't imagine many people are using all the available power 84%+ of the time unless they drive around WOT nearly all the time.

But if you want to spend several hundred extra a year on the off chance that you're feeling frisky at some point then go for it. I'd wager in a blind test no one could tell the difference between what gas is being used. Especially, when there are MUCH wider variations in power output based on simply the change in the weather.

[hassmaschine]

Its not about peak power. You lose torque everywhere - not just at WOT. When i filled our E91 with premium after years of running 87, the difference was night and day. And it already had the 3 stage swap and tune..

[tlow98]

Originally Posted by hassmaschine

Its not about peak power. You lose torque everywhere - not just at WOT. When i filled our E91 with premium after years of running 87, the difference was night and day. And it already had the 3 stage swap and tune..

So given light to moderate throttle load and small pedal travel percents you're utilizing enough capacity of the engine's torque to palpably tell a difference that's not easily replicated by simply applying more throttle?

I guess I'm just so used to seeing dynos that only tell the WOT story I'm missing the part throttle map picture?

[tlow98]

Originally Posted by tlow98

So given light to moderate throttle load and small pedal travel percents you're utilizing enough capacity of the engine's torque to palpably tell a difference that's not easily replicated by simply applying more throttle?

I guess I'm just so used to seeing dynos that only tell the WOT story I'm missing the part throttle map picture?

This just in - I'm an idiot. It's pulling timing which is very noticeable.

[hassmaschine]

yeah, it pulls timing pretty much everywhere you're using even moderate acceleration (which requires torque). Even with the 3 stage swap and tune, our E91 felt about the same as it did with a stock single stage (maybe a small bump in torque). Then I switched to premium (because we were selling it as a "premium" car, haha), the difference was immediately obvious.

Of course, the point is my wife would never know the difference in performance. And to her, spending $500 a year more on gas is stupid (we have 16.4 gallon tanks, not 13), because she couldn't care less how fast the car moves - it was good enough on premium, and absolutely it would not damage the car (or I would tell her so).

That said, she does prefer the MT - in fact given the choice, she always steals my 330i over her E70 X5.

[Jesda]

328 is already a "slow" car by modern standards.

I've filled with 87 and regretted it quickly.

[Run Silent]

Originally Posted by ahlbe1cl

I have a 2011 with N51. It clearly states 91 Octane minimum on the fuel door.

What engine is this? It was mentioned to be a 2013, so that's a cross over year.

My wife drives a X3 35i, that recommends 89 minimum.

I feel no reason why a lower compression NA motor would need more than a higher compression forced induction motor, but I think the OP is simply quoting what his fuel door is recommending and asking the question. I wonder this as well.

Mine is also an N51. A 2013 E93 328i.

[Run Silent]

Originally Posted by E9TOU

Is it really worth the savings?

The current US AAA national averages:
87 cost $2.85/gal x 13 gallons = $37.05
91 cost $3.40/gal x 13 gallons = $44.20
Savings of 87 over 91 = $7.15 per fill up
Assuming you fill up once a week, there are 52 weeks/year, which turns out to a savings of $371.80

Generally speaking, the cost of premium gas is much closer to regular in most locations so I'm not sure why the national averages are so far off. I personally don't think the drop in performance and efficiency is worth it.

$371/yr invested conservatively in good growth stock mutual funds over 25 years would grow to approximately $66,010. So yea, I personally think that 5hp is worth $66K. How about you?

[Welcome to NBA Jam]

Originally Posted by usshelena725

$371/yr invested conservatively in good growth stock mutual funds over 25 years would grow to approximately $66,010. So yea, I personally think that 5hp is worth $66K. How about you?

If having to decide if diverting < 1% of your income to a 25-year conservative investment growth is a concern for your financial future because of gas costs, then you probably should reconsider your car choice and buy a Honda instead.

[gbalthrop]

Originally Posted by hassmaschine

...yes, there are stored knock adaptations, and yes, if you ran for a long time with 87, resetting them after you fill up with premium is probably a good idea.

There are various ignition angle values that can be logged, yes.

Thanks again for the info! One last question:

Which BMW software (ISTA, INPA, or one of the other BMW Standard Tools) can:

(1) Reset knock Adaptations?
(2) Log ignition timing angles?

I'm currently using INPA, but intend to install/learn ISTA, so if you know INPA screens or Functions, F5 (Status), F6 (Steuern) that can be used (at least for "Adaptions"), please identify.

Thanks again,
George

[krhodes1]

Originally Posted by John 070

Premium is 91 octane or higher. Here in the northeast it is 93 (although some unbranded stations skim and sell 92). In Calif., I've heard only 91 is available.

89 is a mid grade that has regular and premium mixed.

Premium in Southern Maine was exclusively 91 for years because that was all the local port brought in. Then a few years ago a couple stations started trucking in 93 from out of state, so you can get 93 if you try. I'm generally of the opinion that using higher than spec'd octane makes no difference, but the stations that sell 93 are usually a little cheaper and convenient to me, so that is what my cars get anyway.

Down in Florida I keep a '17 GTI Sport, which is of course 87 required but Premium recommended for maximum performance. I go by the price spread. If it is less than $.50, I put in Premium, which down there is universally 93. But sometimes it has been +$1! Then it gets 87. The difference is certainly noticeable, but not really dramatic. That car will easily bark the tires going into second gear either way.

Annoyingly my vehicle where the difference is dramatic is my fuel swilling '95 Land Rover Discovery. Putting 87 in that makes if feel like you are towing a trailer, and the fuel economy loss well makes up for the difference in fuel price.