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M2 Technical Topics > N55 Engine / Drivetrain / Exhaust / Bolt-ons / Tuning > Should i be worried about bad gas?

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      12-10-2019, 02:13 PM   #1
GeraldM2
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Should i be worried about bad gas?

Im from CA and recently just saw the thread about a guy blowing his engine on track, with FBO and a stage 1 91 tune. From what i understand the consensus was that the gas he was using was caused irregular IAT which lead to knocking and eventually causing his motor to blow. Ik that CA has really bad gas so im worried that this could happen to me even on a stock tune. I dont plan on tuning until im out of warranty, and im going to get a custom tune rated to CA's shitty gas, but how can i make sure something like this wont happen to me on my stock tune?
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      12-10-2019, 03:09 PM   #2
bmw_m2_cali
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Could this be from bad gas?

https://s.amsu.ng/p0ebEDPcZpVN

It is a stock N55 M2 (minus a few cosmetic touches). I brought it in to the dealer, but they won't look at it for a week and I'm left wondering when I will get my car back/how serious this is.
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      12-10-2019, 03:09 PM   #3
greasypeanut
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I'm on these forums more than I probably should and I also track mine in Cali with a stock tune. I don't recall ever seeing on here and on track any stock tuned m2 blowing an engine.

The issue you will see tune or no tune regarding gas is limp mode while on track due to the fuel pump not being able to pick up any fuel. This happens on right turns leading to straights. The fuel pick up is on the right side of the tank and those right turns swish all the fuel to the left side. I've had an issue even at little more than half tank left.
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      12-10-2019, 03:33 PM   #4
Pray for Mojo
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Quote:
Originally Posted by bmw_m2_cali View Post
Could this be from bad gas?

https://s.amsu.ng/p0ebEDPcZpVN

It is a stock N55 M2 (minus a few cosmetic touches). I brought it in to the dealer, but they won't look at it for a week and I'm left wondering when I will get my car back/how serious this is.
Sounds like the exhaust flap is rattling.
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      12-10-2019, 05:46 PM   #5
bmw_m2_cali
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Quote:
Originally Posted by Pray for Mojo View Post
Sounds like the exhaust flap is rattling.
Glad if that's what it is. Thanks much for the input!

I almost wish I didn't bring it to the dealer and just went to a Dinan dealer or other aftermarket shop...if I'm waiting now for this.
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      12-10-2019, 06:42 PM   #6
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I wouldn't worry about bad gas hurting your unmodified cars.

BMW makes these cars for the entire globe, there is far worse gas than California 91.
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      12-10-2019, 07:22 PM   #7
Anthony1s
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Quote:
Originally Posted by bmw_m2_cali View Post
Could this be from bad gas?

https://s.amsu.ng/p0ebEDPcZpVN

It is a stock N55 M2 (minus a few cosmetic touches). I brought it in to the dealer, but they won't look at it for a week and I'm left wondering when I will get my car back/how serious this is.
Since the sound is only coming from the left exhaust pipe, I would say there is something loose in the actuator valve.
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      12-11-2019, 07:03 AM   #8
squixs
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Quote:
Originally Posted by bmw_m2_cali View Post
Could this be from bad gas?

https://s.amsu.ng/p0ebEDPcZpVN

It is a stock N55 M2 (minus a few cosmetic touches). I brought it into the dealer, but they won't look at it for a week and I'm left wondering when I will get my car back/how serious this is.
That sounds like a loose Exhaust flap. I had the same thing on my old M135i. It's a spring-loaded system, so likely replacing this spring will solve your issue.
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      12-11-2019, 01:05 PM   #9
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Quote:
Originally Posted by GeraldM2 View Post
Im from CA and recently just saw the thread about a guy blowing his engine on track, with FBO and a stage 1 91 tune. From what i understand the consensus was that the gas he was using was caused irregular IAT which lead to knocking and eventually causing his motor to blow. Ik that CA has really bad gas so im worried that this could happen to me even on a stock tune. I dont plan on tuning until im out of warranty, and im going to get a custom tune rated to CA's shitty gas, but how can i make sure something like this wont happen to me on my stock tune?
To answer your question briefly... Yes, you should be worried about bad gas, but only so as to be mindful.

There are a few things that a DME can do if it's seeing pre-ignition problems, which are usually caused by insufficient octane:
  • Pull timing
  • Reduce boost
  • Pump in more gas (to cool the combustion)
In the thread you referenced, the owner got several limp mode situations, and even read a code that mentioned knock issues but he continued anyway. We also know from his logs that the IATs were very high, but that's about all we know.

The theory is that because of low octane and high IATs, the DME tried to pump more gas but wasn't able to because the HPFP was already at the limit. This may have actually resulted in less gas when more was needed, causing the catastrophic failure.

Now on to what bad gas means for us...

There are two issues with CA gas, one is that it's low octane (min 91 AKI / ~94.75 RON / ~87.25 MON) and low Sensitivity (7.5), which is the difference between RON and MON; higher is better. The other is that it's less energy dense, mostly because of the added Ethanol, which means that more needs to be pumped to achieve the correct Air / Fuel mixture, putting more strain on the HPFP than with other fuels.

Keeping IATs down is important, so upgrading the FMIC even for stock vehicles running CA gas will provide a benefit.

Run 1 step cooler plugs to reduce the temperature around them. It's a small change, but many have seen less timing issues after changing them.

Running the highest octane you can will help, either by blending more E85, up to about E20, or by using Octane Boosters or avoiding the issue altogether and using Race Gas. Keep in mind that adding E85 will further strain the HPFP and so may not be the best approach.

Consider WMI to improve Fuelling, IATs and Octane in one hit... It's another thing to keep an eye on and another thing to fail, but it solves the issues with CA fuel pretty much totally.

Once you're tuned, keep an eye on logs. Make sure that if you run an OTS map, you're using the ACN maps rather than using the 93 AKI map and 'hoping for the best'.

If you track the car, flash a more conservative map and keep an eye on logs real time. The BM3 system has a dashboard where you can monitor IATs and timing with dials on screen. If you notice any warnings, pay attention to them.

For running on street, I'm not aware of anyone who has had issues with a FBO tuned vehicle. There are hundreds of tuned M2s and even more N55 motors that are running CA pump gas. Any tuner that's worth working with will know all of this, so there isn't much to worry about.
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