Bad Gas??
- Thread starter samlee4444
- Start date
![[:D]](/images/smilies/biggrin.png "Big Grin [:D]")
What about 94? Anyone used that? There is a Sunoco (sp?) gas station around where I live that has 94 on sale 2 days a week, I think it's just 2 more cents per gallon than 93. I didn't fill up there in a long time since I usually get Costco gas because I never had a problem with it and it is SO much cheaper, 93 is cheaper than 89 on other gas stations (no kidding).
It could be the station you filled up at. Maybe they have a slight bit of moisture in their tanks or got a mix of bad gas themselves. I have used both 91 and 93 octane gas without any problems at all with either. I don't believe it is the octane level you are using as it is more likely the gas and where it was purchased.
Okay, I have not read most of the replies, so I am not fully up to date with this stuff, but I just wanted to say that there are differences in quality of gas based on the different gas stations. I once read this test performed by Maxim (yup, Maxim) and they concluded that Amoco, Exxon, and Mobil served the cleanest, highest-quality gas. I think the worst was CITGO or Chevron or something.
Bryan330i said:
So far I did not find 93 here. ![[8]](/images/smilies/icon_smile_8ball.gif "Retarded [8]")
But I did find 100 at a couple of 76 stations in town. I wonder how it would run on that. [fake]
But I did find 100 at a couple of 76 stations in town. I wonder how it would run on that. [fake]
From the 2004 330 CiC Owner's Manual...
----snip
Fuels
Use unleaded gasoline only. Fuels containing up to and including 10 % ethanol or other oxygenates with up to 2.8 % oxygen by weight - that is, 15 % MTBE or 3 % ethanol plus an equivalent amount of co-solvent - will not void the applicable warranties respecting defects in materials or workmanship. Field experience has indicated significant differences in fuel qualtiy - volatility, composition, additives, etc. among gasolines offered for sale in the United States and Canada. The use of poor-quality may result in drivability, starting and stalling problems, especially under certain environmental conditions, such as high ambient temperature and high altitude. Should you encounter drivability problems which you suspect could be related to the fuel you are using, we recommend that you respond by switching to a recognized, high-quality brand.
Failure to comply with these recommendations may result in unscheduled maintenance.
----snip
Fuel Specifications
The engine uses lead-free gasoline only.
Required fuel:
Premium Unleaded Gasoline,
min. 91 AKI.
AKI= Anti-Knock Index
---snip
The following talks about about the relationship between octane and AKI from Chevron (link below). Note: I have put some pertient items in bold
Knock-free engine performance is as important as good driveability. Octane number is a measure of a gasoline's antiknock performance - its ability to resist knocking as it burns in the combustion chamber. There are two laboratory test methods to measure the octane number of a gasoline (see Chapter 3). One yields the Research octane number (RON), the other, the Motor octane number (MON). RON correlates best with low speed, mild-knocking conditions; MON correlates best with high-speed and high-temperature knocking conditions and with part-throttle operation. For a given gasoline, RON is always greater than MON. The difference between the two is called the sensitivity of the gasoline.
Because RON and MON are measured in a single cylinder laboratory engine, they do not completely predict antiknock performance in multicylinder engines. There is a procedure to measure the antiknock performance of a gasoline in vehicles (see Chapter 3). The resulting value is called Road octane number (RdON). Since vehicle testing is more involved than laboratory testing, there have been a number of attempts to predict RdON from RON and MON. The equations take the form:
RdON = a(RON) + b(MON) + c
A good approximation for RdON sets a=b=0.5 and c=0, yielding (RON + MON)/2, commonly abbreviated (R+M)/2. This is called the Antiknock Index (AKI).The Federal Trade Commission requires dispensing pumps to be labeled (posted) with the gasoline's AKI. (The gasoline being dispensed must have an antiknock index equal to or greater than the posted value.) Owner's manuals also must indicate the octane requirement of vehicles by AKI. (Older owner's manuals of some foreign cars specify RON; some more recent ones specify both RON and AKI.)
Neither the AKI nor the several other single-value indices that have been developed work for all vehicles. The performance of some vehicles correlates better with RON or MON alone than with a combination of the two. And for a given vehicle, the correlation can vary with driving conditions. (See Chapter 5 for the variables that affect an engine's octane requirement.)
As the formula indicates, gasolines with the same AKI can have different RONs and MONs. This may explain why a vehicle knocks with some fill ups of the same brand but not with others; or why it knocks with one brand of gasoline but not with another. Of course, for a comparison to be valid, the vehicle must be operated under identical conditions, which is not easy for the typical driver.
Generally, three grades of unleaded gasoline with different AKIs are available in the United States — regular, midgrade and premium. At sea level, the posted AKI for regular-grade is usually 87 and for midgrade, 89. The AKI of premium-grade varies more, ranging from 91 to 94.
The posted AKIs gasoline are lower in the Rocky Mountain states. These altitude gasolines historically provided the same antiknock performance as higher-AKI gasolines at sea level. The octane requirement of older-model engines decreases as air pressure (barometric pressure) decreases the barometric pressure is lower at higher elevations.
Since 1984, vehicles have been equipped with more sophisticated control systems, including sensors to measure, and engine management computers to adjust for, changes in air temperature and barometric pressure (see Chapter 5). These vehicles are designed to have the same AKI requirement at all elevations and the owner's manuals specify the same AKI gasoline at all elevations.
It is difficult for a driver to know whether a gasoline has the antiknock performance the engine requires when the engine is equipped with a knock sensor system. These systems, which temporarily retard spark timing to eliminate knocking, are installed on many late-model engines (see Chapter 5). Retarding the spark reduces power and acceleration. The knock sensor responds so quickly that the driver never notices the knock. Loss of power and acceleration will be the only clues that the antiknock quality of the gasoline does not meet the vehicle's octane requirement.
Using gasoline with an antiknock rating higher than that required to prevent knock or to prevent spark retardation by the knock sensor will not improve a vehicle's performance.
http://www.chevron.com/prodserv/fuels/bulletin/motorgas/ch1a.shtml
I can only imagine that newer BMWs adjust for altitude, but those with older BMWs may be able to get away with lower AKI gasoline if at higher altitudes.
----snip
Fuels
Use unleaded gasoline only. Fuels containing up to and including 10 % ethanol or other oxygenates with up to 2.8 % oxygen by weight - that is, 15 % MTBE or 3 % ethanol plus an equivalent amount of co-solvent - will not void the applicable warranties respecting defects in materials or workmanship. Field experience has indicated significant differences in fuel qualtiy - volatility, composition, additives, etc. among gasolines offered for sale in the United States and Canada. The use of poor-quality may result in drivability, starting and stalling problems, especially under certain environmental conditions, such as high ambient temperature and high altitude. Should you encounter drivability problems which you suspect could be related to the fuel you are using, we recommend that you respond by switching to a recognized, high-quality brand.
Failure to comply with these recommendations may result in unscheduled maintenance.
----snip
Fuel Specifications
The engine uses lead-free gasoline only.
Required fuel:
Premium Unleaded Gasoline,
min. 91 AKI.
AKI= Anti-Knock Index
---snip
The following talks about about the relationship between octane and AKI from Chevron (link below). Note: I have put some pertient items in bold
Knock-free engine performance is as important as good driveability. Octane number is a measure of a gasoline's antiknock performance - its ability to resist knocking as it burns in the combustion chamber. There are two laboratory test methods to measure the octane number of a gasoline (see Chapter 3). One yields the Research octane number (RON), the other, the Motor octane number (MON). RON correlates best with low speed, mild-knocking conditions; MON correlates best with high-speed and high-temperature knocking conditions and with part-throttle operation. For a given gasoline, RON is always greater than MON. The difference between the two is called the sensitivity of the gasoline.
Because RON and MON are measured in a single cylinder laboratory engine, they do not completely predict antiknock performance in multicylinder engines. There is a procedure to measure the antiknock performance of a gasoline in vehicles (see Chapter 3). The resulting value is called Road octane number (RdON). Since vehicle testing is more involved than laboratory testing, there have been a number of attempts to predict RdON from RON and MON. The equations take the form:
RdON = a(RON) + b(MON) + c
A good approximation for RdON sets a=b=0.5 and c=0, yielding (RON + MON)/2, commonly abbreviated (R+M)/2. This is called the Antiknock Index (AKI).The Federal Trade Commission requires dispensing pumps to be labeled (posted) with the gasoline's AKI. (The gasoline being dispensed must have an antiknock index equal to or greater than the posted value.) Owner's manuals also must indicate the octane requirement of vehicles by AKI. (Older owner's manuals of some foreign cars specify RON; some more recent ones specify both RON and AKI.)
Neither the AKI nor the several other single-value indices that have been developed work for all vehicles. The performance of some vehicles correlates better with RON or MON alone than with a combination of the two. And for a given vehicle, the correlation can vary with driving conditions. (See Chapter 5 for the variables that affect an engine's octane requirement.)
As the formula indicates, gasolines with the same AKI can have different RONs and MONs. This may explain why a vehicle knocks with some fill ups of the same brand but not with others; or why it knocks with one brand of gasoline but not with another. Of course, for a comparison to be valid, the vehicle must be operated under identical conditions, which is not easy for the typical driver.
Generally, three grades of unleaded gasoline with different AKIs are available in the United States — regular, midgrade and premium. At sea level, the posted AKI for regular-grade is usually 87 and for midgrade, 89. The AKI of premium-grade varies more, ranging from 91 to 94.
The posted AKIs gasoline are lower in the Rocky Mountain states. These altitude gasolines historically provided the same antiknock performance as higher-AKI gasolines at sea level. The octane requirement of older-model engines decreases as air pressure (barometric pressure) decreases the barometric pressure is lower at higher elevations.
Since 1984, vehicles have been equipped with more sophisticated control systems, including sensors to measure, and engine management computers to adjust for, changes in air temperature and barometric pressure (see Chapter 5). These vehicles are designed to have the same AKI requirement at all elevations and the owner's manuals specify the same AKI gasoline at all elevations.
It is difficult for a driver to know whether a gasoline has the antiknock performance the engine requires when the engine is equipped with a knock sensor system. These systems, which temporarily retard spark timing to eliminate knocking, are installed on many late-model engines (see Chapter 5). Retarding the spark reduces power and acceleration. The knock sensor responds so quickly that the driver never notices the knock. Loss of power and acceleration will be the only clues that the antiknock quality of the gasoline does not meet the vehicle's octane requirement.
Using gasoline with an antiknock rating higher than that required to prevent knock or to prevent spark retardation by the knock sensor will not improve a vehicle's performance.
http://www.chevron.com/prodserv/fuels/bulletin/motorgas/ch1a.shtml
I can only imagine that newer BMWs adjust for altitude, but those with older BMWs may be able to get away with lower AKI gasoline if at higher altitudes.
Bryan330i said:
So far I did not find 93 here. But I did find 100 at a couple of 76 stations in town. I wonder how it would run on that. [fake]
But I did find 100 at a couple of 76 stations in town. I wonder how it would run on that. [fake]
But yeah, 100 octane (unleaded) can give you more room before you knock if your car is really hopped up, but especially with a stock ECU you won't feel a difference. but man.... gotta love the smell of that nice race gas
![[hihi]](/images/smilies/icon_smile_hihi.gif "Hi Hi [hihi]"){kind=icon}
At one point my car was riding so rough I even had BMW look at it and they told me they didn't see any physical problems, however low octane gas (i was using 89) could be causing the problem.$80.00 to fill up
So I thought I would try the Competition 100. WOW, is it expensive.![[ohcrap]](/images/smilies/icon_smile_ohcrap.gif "Oh Crap! [ohcrap]")
It would be like $80.00 to fill up. ![[:(!]](/images/smilies/icon_smile_angry.gif "Angry [:(!]")
So I tried a mix to see how it runs, I got 4 gallons 91 (the highest here) and 4 gallons 100 to see if it runs better. It wants to die sometimes at stops, like frolf said, this is likely something else.
So I thought I would try the Competition 100. WOW, is it expensive.
It would be like $80.00 to fill up. So I tried a mix to see how it runs, I got 4 gallons 91 (the highest here) and 4 gallons 100 to see if it runs better. It wants to die sometimes at stops, like frolf said, this is likely something else.