996 C2 check engine - fuel problem solved

Thanks to all who posted responses on my question about experiences with the check engine light. My problem turned out not to be poor fuel (although I still have bad gas from that Mexican lunch). Turns out it was a dead coil, so the car was running on 5 cylinders. Interestingly, although it idled poorly, it still ran okay. There also wasn't much evidence of unburned fuel overheating the catalytic converter or anything else like that, although running unburned fuel through a cylinder for an extended period can wreak havok on things like rings and valves. Maybe the computer stops fuel from entering a bad cylinder? All should be interested in the dealers recommendation, which was to replace all 6 coils and spark plugs for a total of $970 (that's the "bend over, this won't hurt a bit" part). Cheap guy that I am I opted o replace the fauty coil and plug for $270, which is still a bit of a "drilling". I realize that any of the other 5 could be near the end of their life, but apparently you can drive with a dead coil in a "limp home" mode, so I will replace the next ones when they need it.

Bad fuel seems to be fairly rare. Glad your car is running again even though dealer wanted to clean out your piggy bank. At least that problem is behind you and you'll know what it is the next time.

Keep an eye on this. My 996 engine had a "bad" coil that was allegedly fixed 3 times before the engine went grenade on me. Fortunately I had warranty and PCNA replaced the engine at no cost. Hopefully you will be fine and this will never be an issue, but keep an eye on your CEL.

Strange....but I just had the same dogone thing happen. I cheaped out and went and got a tank of gas at Costco. Got home after a brisk drive, parked the car, then got back in and fired it up. It felt like it was running on 4 cylinders...noticeable vibration like all the cylinders were'nt firing. Check engine light started flashing so I pulled over and stopped the engine immediately. Waited a bit then fired back up....check engine light stayed on steady so I drove over to Autozone and used the code reader. It threw a 0300 code and read out "multiple cylinder misfire" and "random cylinder misfire". I was going to drive to the dealership and have them check it out, but after driving on the freeway for about 20 miles, the CEL cleared itself. All I can figure is bad gas. but I won't be buying Costco gas again....at least not for the Porsches.

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Around me COSTCO gas is delivered by Exxon. I use it in my 964 for 4 years and the TT for the last year without ever having gas problems. Ask them who delivers their gas. You may be surprised.

There's more here on "getting drilled" by the dealer. My total bill for the $270 coil was $802! That's $270 for the coil, $426 for an oil change (!!!!!), and $106 for our beloved government and miscellaneous expenses to keep the dealer's speedboat gassed up. Normally I would like to have dinner with someone before I let them do that to me ;-). And they wonder why we avoid the dealer.

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+1 Bad gas is very very rare. Look at it this way - what constitutes "bad gas"? Well, usually it's high sulfur content, buyt not exclusively. All fuel for a region comes from the same pipeline, regardless of who sells it. The distributor/retail company then adds a detergent package to it. Bad gas could be caused by poor refining or improper charging of additives. Both are equally unlikly in today's world. For "bad gas" to happen it would mean that all fuel delivered to a region (refining problem) was improperly refined and all brands would equally be affected, or the additive package was badly charged at incompetently high levels and that would also affect a large number of gas stations. Both events would be newsworthy. I get a kick out of people picking on fuel when the difference between all brands is really in the noise.

get a kick out of people picking on fuel when the difference between all brands is really in the noise. What do you mean by the difference is in the noise? I did ask the Costco trucker who was delivering the gas and he told me he got the gas from the Exxon refinery....same place most of the local stations got it. It just gets delivered in a generic truck. He laughed at me when I suggested that somehow the gas was inferior. I guess Jimq is right....but the guys down at my boat shop swear that you should only use either 76 or chevron in the bass boats......I think we'll find a variety of opinions on this....

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I meant what I said. Gasoline gets refined to a certain grade. It then gets fed into a pipeline with gas from all other refineries. It gets fed out of the pipeline into a storage tank. From there distributors add their generic or proprietary additive package (read <100ppm of additive added) and it goes out in tracks to gas stations. The only difference between any fuel, regardless of the gas station that you buy it from is the additive package. The effect of the additive package has been written about ad nauseum and has little effect upon the performance of a car during it's lifetime when studied under controlled conditions. Can there be a difference between the amount of engine buildup depending upon the brand of fuel you buy? Sure, Shell's V-power has a detergent package 5x that of the Federally mandated minumum and that has been shown to minimize build-up. Does that make a difference to performance and maintenance costs of a modern engine during it's lifetime? I've seen no scientific study that shows that it does. Some might claim difference in fuel economy, I would say that those that claim it either have something to gain by claiming it (i.e, they're selling something), or have not done a controlled study and are basing their comments on "feel". There is no such thing as "inferior" gas, much as the name brands would like people to believe.

Once addendum before I forget. The GAS STATION that you buy from does matter. A gas station with poorly maintained tanks, or an an older gas station can have an impact upon the quality of you fuel. Why? 2 reasons: i) degrading fuel tanks, although federal and state laws have mostly solved that issue and forced gas stations with older, degrading tanks to shut down (or upgrade). ii) older gas stations are more likely to have higher moisture levels in their tanks. Most of the time that doesn't matter, as water and fuel are not miscible and the water settles to the bottom of the tanks. That's fine, unless you happen to fill up at the time of the fuel delivery from the tank truck. The pumping of new fuel into the tank will cause the water collected at the bottom of the tank to be mixed up and pumped into the cars lucky enough to be around at the time of delivery (or shortly afterwards). Plus, if there happens to be sediment on the bottom of the tank for any reason that will also make it's way into your fuel tank. Never fill up your car at the same time as a fuel delivery is happening, as that can be a recipe for trouble. I've actually drive away from a gas station if I'm unlucky enough to arrive while the delivery is occurring.

Interesting discourse on gas. This is exactly why I originally suspected the gas - it was a blustery and rainy day so everything was wet already. It was a gigantic gas station that's been there and gigantic for 25 years. And there are always big tankers in the parking lot so you can never tell if their tanks have just been refilled or not. On the discount gas subject - I usually buy from a nearby no-name station that's only 3 or 4 years old (= new underground tanks). Never a problem.

100 octane baby !!!