Anyone have misfires running non oxygenated fuel?

So before last winter I filled my tank with non oxygenated fuel and added sea foam, come spring ran the can and had various misfires which I put down to the sea foam (first time I tried it vs stabil). So as I am getting close to retiring the car for winter I filled it with Jon oxygenated fuel and after running a full tank you guessed it misfires. Anyone experienced this?

Sorry for the crap spelling, 2 glasses of red wine and iPad autospell

Don't use Seafoam in the fuel. It is a blend of oil, naphtha, and ethanol and won't do anything good for your fuel system or engine. Non-oxygenated fuel is probably not the problem, per se. The problem was probably the fuel just went stale and the presence of Seafoam just made things worse. It is important to fill up the tank with fresh fuel. And fuel with the right octane. This applies whether it is first tank of the driving season, or the last tank.

Thanks Macster, but to be clear I haven't run seafoam in the car since last winter. Last 1 1/2 gas fills this fall I have added non oxygenated fuel and the misfires have started to occur. Hence the only common cause of the misfire is the non oxy fuel not seafoam

Sorry for the ignorance but what is non oxygenated fuel?

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If no Seafoam is involved then just oxygenated fuel and it is reasonably fresh then it is possible the fuel is the cause of the misfires. What is the fuel oxygenated with? Around here (northern CA) ethanol is the only oxygenate additive. The only other oxygenate I can recall being used was MTBE (Methyl tert-butyl ether) but I thought this was phased out because the EPA mandated the use of ethanol. Are you perchance filling up with a gas/ethanol blend that is more than "10%" ethanol? I put 10% in quotes as my info is even though the sticker on the pump says the fuel has 10% ethanol refineries have kept the blend to the 7% to 8% range. However, the EPA was pushing a 15% ethanol blend and in fact mandated it, but then after protests about concerns of running this high an ethanol blend by just about every refinery and automaker has backed off in the form of offering waivers. Still, there may be pumps offering 15% (and "10%") ethanol gasoline (and don't forget E85). If you filled up with gasoline with 15% ethanol this could very well be the cause of the misfires. (And I don't want to think how the engine would react if you filled up with E85) Where does this leave you? Well, if you filled up with 15% gasoline/ethanol (or worse) then avoid that in the future. If you filled the tank with 10% gasoline/ethanol fuel then consider changing brands. Somewhere in the owners manual Porsche says something to the effect if the engine doesn't run well with one particular brand of fuel to switch to another brand, try another brand of fuel. Probably should have asked this before now, but when does the misfiring occur? Cold start? Warm start? On the road? Under hard acceleration? Does the engine manifest rough running? My concern is if the misfiring is severe you might want to go to the trouble of having the fuel tank emptied and then refilling it with another brand of fuel, and one with just the 10% blend of ethanol unless you can find ethanol free gasoline in your area. My other concern is the misfiring is not due to the fuel but something else. Which prompts the question are the plugs due to be changed? If the car is a daily driver and you live in a region where the humidity is high the coils can go away, so even if the plugs are ok the coils may not be. Last, but not least, you probably want to consult with your trusted tech on this. If oxygenated fuel causes misfires he's probably encountered this before and can advise you. If he hasn't then the odds are higher the misfires are not directly the result of oxygenated fuel but arise from another problem and one that needs to be id'd and addressed.

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Non-oxygentated fuel is fuel (gasoline in this context) that is not blended with an oxygen carrying chemical. The most common chemical used for blending is ethanol.

New plugs this spring (when it first started showing misfires). Misfires are random, cleared them each time to see if it was a particular coil. This to me says it is not coil related. Car runs perfect on oxygenated 10% blend fuels, no misfires. Filling with non-oxygenated fuels seems to cause these random misfires. I think I know what the issues is - Fuel related, but I wondered if anyone had a similar experience, or could explain why. I was always under the assumption the cars would run better with pure gasoline vs blended.

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Good grief, my reading comprehension has just gone to pot. You are using *non* oxygenated fuel and the engine misfires with this fuel while with oxygenated fuel the engine doesn't misfire. Ok, I think I have it. (Took me long enough...sigh.) The misfires can still arise from the engine's sensitivity to the in this case the non-oxygenated fuel. While generally all other things being equal (mainly the octane rating and freshness, oh and price) non-oxygenated fuels are preferred, if the engine doesn't like the non-oxygenated fuel, then you need to find something the engine likes and if it is oxygenated fuel so be it. As long as the engine runs ok with this oxygenated fuel and you are otherwise ok with it -- assuming it costs about the same, is readily available, of course has the required octane rating -- I would not worry about why the engine didn't appear to like the non-oxygenated fuel. If the engine begins to act up -- and I do not necessarily believe it will act up -- with the oxygenated fuel then you will have to deal with that when (if) the time comes. What you may find if this ever comes about is whatever you find is causing the engine to negatively react to the oxygenated fuel was also causing it to negatively react to the non-oxygenated fuel. Afterwards you may then find the engine is quite tolerant of non-oxygenated fuel.

What is the octane rating on the non oxygenated fuel? The reason I ask is that ethanol is by nature a high octane fuel. I read somewhere that pure ethanol has a 113 octane rating. Maybe the non oxy fuel is too low in octane and your engine is protesting this?? To be clear I am not a proponent of oxygenated fuel. There are pros and cons with ethanol. As other's suggested I too would suspect that the non-oxy fuel might be old and stale.

I am pretty sure the non Oxy fuel was 91 or 93. Thats why I just dont get why it doesnt run very will with it. I am fine running oxy fuel as thats whats readily available here, and as stated the car runs great on it. I only put the non oxy fuel in before I stored the car, my assumption was having non oxy fuel & Stabil in the system over winter would be the best plan. Looks like I will still stick with blended oxy gas and a dose of Stabil. Either way I'm still looking at a bleak winter without the 911 on the road

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So, if non-oxygenated fuel is preferred, what brand are we talking about?

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Based on what I have picked up over the years my advice is to use a name brand fuel with the proper octane rating. Buy from a busy station. This ensures the fuel is the freshest. (Real busy stations can get deliveries several times a day. One station, a Shell station off of I-35 in Olathe, KS, got up to 4 deliveries a day.) Another benefit is generally busy stations offer the lowest or most competitive prices.)

Any benefit to filling up with so-called top-tier gasoline? Shell BP Costco - believe it or not.

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This is gonna be an oil type question.

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Personally I believe yes, there is a benefit. From the link: http://www.toptiergas.com Here's some info on top tier: Top Tier Detergent Gasoline TOP TIER Detergent Gasoline is the premier standard for gasoline performance. Seven of the world's top automakers, BMW, General Motors, Honda, Toyota, Volkswagen, Mercedes-Benz and Audi recognize that the current EPA minimum detergent requirements do not go far enough to ensure optimal engine performance. Since the minimum additive performance standards were first established by EPA in 1995, most gasoline marketers have actually reduced the concentration level of detergent additive in their gasoline by up to 50%. As a result, the ability of a vehicle to maintain stringent Tier 2 emission standards have been hampered, leading to engine deposits which can have a big impact on in-use emissions and driver satisfaction. These automakers have raised the bar. TOP TIER Detergent Gasoline help drivers avoid lower quality gasoline which can leave deposits on critical engine parts, which reduces engine performance. That's something both drivers and automakers want to avoid. There's more. EVO (UK published car mag) that did a fuel test a few years ago. It found that while discount/supermarket fuel did OK the results were inconsistent and blamed this on the reliance of different fuel suppliers. Discount/supermarket gas stations sell on price and they must shop around for the best price. EVO found that name brand stations fuels were consistently better but even so found this was not always the case. This inconsistenty was traced to the fuel being stale. Hence the recommendation to buy from a busy station. As I think I mentioned before my experience was using a discount station for gas vs. using Shell station for gas was my 02 Boxster would manifest a P0430 error more often. The converter was marginal due to -- as it turned out -- a loose brick. But it was informative that it was more sensitive to the different brands of gasoline.