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Discussion Starter · #1 ·
I recently filled up with some Sams Club gas in Pomona when it was very hot recently. Right before this I know my car (335 coupe auto, jbs2) was performing normally because I had a friend with me and we were blasting around a little just because. A few days later I noticed that when I would take off from my favorite freeway onramp light I would experience what felt like severe turbo boost and then it would kick in around 4k+. I normally get some wheelspin with DTS active and suddenly nothing...

I thought about the gas and went and spent the $8.49/gallon for about 5 gallons of 100 octane fuel and another 6 gallons of standard 91 to fill it up the rest of the way. I estimate I had about 5 gallons of potentially poorly mixed fuel so now I should be well back above 91 even if the residual fuel was purely 87. Since then I think it has returned a little more normal but I still think it is far from what it was only a couple weeks ago.

My questions:
Do you think this is a case of bad gas even though I'm leading you this way?
Is there a way to reset the computer to learn the status of the engine/octane?
I think this might at least tell me if I have hurt the engine.
Has anybody with the JBS2 found that the computer fully adapts or over adapts to the increased performance conditions and steps it back down?

Thx
MS2008
 

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My $0.02.

One bad tank, heck probably even two, isn't going to really hurt your engine. Your computer will simply do a back of the spark advance. You'll lose lots of power, some fuel economy, that's about all.

One classic symptom of bad gas IS surging, I should add.
 

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Why would you put 100 octane in your car? There is no advantage in going above the recommended rated octane fuel. I don't know what octane your piggyback provider recommends but I doubt it's 100. The engine management system won't advance the timing or create extra boost over and above how it's programmed so the extra octane does no good.

Thanks, Mike.
 

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Why would you put 100 octane in your car? There is no advantage in going above the recommended rated octane fuel. I don't know what octane your piggyback provider recommends but I doubt it's 100. The engine management system won't advance the timing or create extra boost over and above how it's programmed so the extra octane does no good.

Thanks, Mike.
If you read his original post, you would see that he did it to even out the low octane level that could have been caused by 87 octane.
 

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If you read his original post, you would see that he did it to even out the low octane level that could have been caused by 87 octane.
Thanks, sorry for the confusion. To tell the truth I'm still confused because he never said the Sam's Club gas was 87 octane he just thinks it might have been:dunno:. Either way I doubt that 87 octane would cause the problems he experienced. It would lead only to reduced power and fuel economy. The bad gas theory makes more sense but this is not octane related.

Thanks, Mike.
 

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I recently filled up with some Sams Club gas in Pomona when it was very hot recently. Right before this I know my car (335 coupe auto, jbs2) was performing normally because I had a friend with me and we were blasting around a little just because. A few days later I noticed that when I would take off from my favorite freeway onramp light I would experience what felt like severe turbo boost and then it would kick in around 4k+. I normally get some wheelspin with DTS active and suddenly nothing...

I thought about the gas and went and spent the $8.49/gallon for about 5 gallons of 100 octane fuel and another 6 gallons of standard 91 to fill it up the rest of the way. I estimate I had about 5 gallons of potentially poorly mixed fuel so now I should be well back above 91 even if the residual fuel was purely 87. Since then I think it has returned a little more normal but I still think it is far from what it was only a couple weeks ago.

My questions:
Do you think this is a case of bad gas even though I'm leading you this way?
Is there a way to reset the computer to learn the status of the engine/octane?
I think this might at least tell me if I have hurt the engine.
Has anybody with the JBS2 found that the computer fully adapts or over adapts to the increased performance conditions and steps it back down?

Thx
MS2008
It's possible the gas was bad, but could also be a sign of a fuel pump failure, etc. Best to drive nicely until the crap gas is gone and fill up with quality gas.
 

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Why would you put 100 octane in your car? There is no advantage in going above the recommended rated octane fuel. I don't know what octane your piggyback provider recommends but I doubt it's 100. The engine management system won't advance the timing or create extra boost over and above how it's programmed so the extra octane does no good.

Thanks, Mike.
Generally the higher the octane the more power you will make on the 335i, up to a point. And adding race gas with a piggyback helps even more. The ECU is setup to adapt between 87-94 octane so there is a lot of room in there.

Having said that if his original tank was bad or had water, I don't think adding race gas will average it out.
 

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Discussion Starter · #9 ·
Thanks for the feedback everybody.

I was thinking the gas was low octane and not that it was actually poor quality. I will likely try to run it very low and give it a fresh fillup and see how it reacts.

Assuming low octane. Does anybody have any experience if the computer will slowly try to return to normal spark or will it just try full advance every time and if it knocks retard it again?

If its a slow return, how about resetting the computer? Will a battery disconnect do it or ???

Sams club and costco sell so much gas I expected it to be fresh and not contaminated.

Seperate observation on gas prices (hijacking my own thread) :)
Normally my car gets whichever station is near when it needs gas for the most part. I figure that saving 10 cents a gallon no longer makes sense to drive 5 miles out of your way to get. A 12 gallon fillup saves $1.20 at that difference. This equals about 1/4 a gallon of gas. At 20 mpg around town that 5 miles of extra driving just ate up the money you saved. It now makes some financial sense as well as good practice to give your car the brand of fuel you think is best for it.
 

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Thanks, sorry for the confusion. To tell the truth I'm still confused because he never said the Sam's Club gas was 87 octane he just thinks it might have been:dunno:. Either way I doubt that 87 octane would cause the problems he experienced. It would lead only to reduced power and fuel economy. The bad gas theory makes more sense but this is not octane related.

Thanks, Mike.
Mike,
Hey man. After re-reading my response to your post, I think I may have came off as an a$$hole. That was not my intentions at all and just wanted to say sorry if that's the way I came off:thumbup:.
 

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Seperate observation on gas prices (hijacking my own thread) :)
Normally my car gets whichever station is near when it needs gas for the most part. I figure that saving 10 cents a gallon no longer makes sense to drive 5 miles out of your way to get. A 12 gallon fillup saves $1.20 at that difference. This equals about 1/4 a gallon of gas. At 20 mpg around town that 5 miles of extra driving just ate up the money you saved. It now makes some financial sense as well as good practice to give your car the brand of fuel you think is best for it.
I'll go like a mile further to a different Chevron because it's not as close to the interstate as the other Chevron and as a result is a few pennies cheaper per gallon for premium. Really though I decided a while ago that a) my car would get nothing but premium (93 in Atlanta) Chevron and b) life's too short trying to save $.05/gallon on something that is a luxury (given that you could be in a Honda Civic and stretching each gallon much further).
 

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Mike,
Hey man. After re-reading my response to your post, I think I may have came off as an a$$hole. That was not my intentions at all and just wanted to say sorry if that's the way I came off:thumbup:.
Ryan, no problem at all. I did not take it that way. I misread the OP and you put me straight.

Thanks, Mike.
 

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Hello, MS2008. Since you hijacked your own thread, I'll chime in here. I can't believe no-one has done it yet! Anyway...

I've had bad gas in my 335 and it never seemed to affect the car's performance.

:D

Snaxster
 

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Hello, MS2008. Since you hijacked your own thread, I'll chime in here. I can't believe no-one has done it yet! Anyway...

I've had bad gas in my 335 and it never seemed to affect the car's performance.

:D

Snaxster
What makes you think it was bad gas?

ML
 

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Discussion Starter · #17 ·
My passengers insisted on keeping all the windows open. :eek:
mlaynemd stepped right into that one.

I'll put Snaxster on my list of people to never buy a used car from!
 

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