Dennis C

I'm not sure why, but today I went to drive the C4S and was greeted with a flashing CEL and a message to drive to the workshop. The car fires up without a problem, but it idles rough immediately. Giving it a little gas makes it run smoothly. The CEL comes on after about 15 - 20 seconds. I turned it off and then started it again, and it did the same thing. The car ran fine yesterday, but not today! Unfortunately our Porsche dealer is closed until Monday, so I'll have to wait.

We are between houses - we sold our house here in Indiana and moved into temporary housing until we close on our new house in Colorado in May. The car was parked on a hill all night - with the front wheels elevated compared to the rear wheels. I'm not sure if this could possibly create my problem... but who knows...

I'll search here and see what I can find...

Sneaky Pete

Maybe some sediment in your tank? With the car at an incline, maybe the sediment rested over the opening of the fuel line and it clogged your fuel filter? Just guessing on this.....

Dennis C

I was wondering about something like that too...

Dennis C

I just went out and started it again. The CEL is solid now, not flashing. Still runs rough. Having it sent to the dealer on a flatbed on Monday.

Macster

Flashing check engine light is sign 3-way converters at risk of damage.

Without error codes tough to say but likely the CEL due to misfires. The rate of misfires is such the converters could overheat. (Misfiring cylinders dump too much raw gas into the exhaust which is burned in the converters and this can overheat and damage them.)

If car parked on a hill/incline and if the fuel level low (low fuel light on low at least and this may not be low enough though it depends upon the steepness of the incline) the engine could have been partially run out of gas. This will cause misfires. IIRC the fuel level is recorded and if the fuel level extremely low no error codes are recorded cause the misfires are attributed to the low fuel level.

Another possibility is the fuel has become contaminated and when the car sits the fuel stratifies and if the car parked on an incline a particularly unpleasant layer of "bad" gas develops right at the fuel pump intake and this is ingested by the fuel pump, misfires are possible. Generally gas is ok but in some areas leaking tanks and ethanol in fuel work to really accumulate water in the fuel tank. Ethanol and gas are not real happy and want to separate and with water added to the fuel... The ethanol and water combine and this mixture then becomes even less likely to remain blended with the gasoline.

Upon engine start and vehicle movement the gasoline is agitated and sloshed about and mixed up and the gas/ethanol/water gets blended together again and this stuff is consumed with possibly no further untoward symptoms from the engine.

No one can say without draining the tank - and I'm not suggesting this required this would be between you and your mechanic whether this is a needed action to get the car back on the road again in good health -- but as a preventative measure you could treat the gas tank to a dose of some fuel treatment that could improve the fuel in the tank. Not sure which fuel treatment you should use. Check with your mechanic. Swepco makes one but there are others.

You might hold off adding anything to the gas tank until after your mechanic has had a chance to trouble shoot the symptoms. You don't want to change things right now.

Afterwards, though, your area may have stations with water contaminated gasoline and some periodic fuel treatment may be a good idea.

Of course there are other possible causes to the misfires. When you take car in be sure to ask all error codes be read and written down for your benefit. Post them here. I'd be interested in knowing what they are.

Sincerely,

Macster.

Dennis C

Thanks Macster. I'll ask them about the codes. I really need to get a code reader. It is clearly misfiring, but I don't know why. I'm just going to leave it alone and let the mechanic deal with it. The total run time since this problem developed is about 30 seconds, so I hope that wasn't enough to damage my converters. If so, I guess that will be an opportunity to upgrade to a new set of sport cats!

Thanks for your thoughts.

Barn996

Too bad about the rough idle Dennis,but congrats on selling your home. Are you in Colorado in temporary housing or Indiana?Good luck at the dealer on Monday.

Dennis C

We're in Indiana so the kids can finish school. All our stuff is in a storage warehouse in Golden, CO, but we're still here! We close on the new house on May 14th. The kids finish May 28th, so I'll meet the movers on the 14th, and then come back and get the whole crew at the end of the month.

Macster

30 seconds not long enough to damage the converters. Porsche is responsible for the converters (as are all car makers) for the duration of the emissions warranty and the engine controller is very quick to flash the CEL in plenty of time to avoid under most conditions converter damage.

You are doing the right thing, getting the car flat bedded to the dealer come Monday.

Hope you like Golden. I'm not that familiar with it, but it is a nice place. I've spent a night or two there and maybe a day or two running about when passing through CO on my way elsewhere. A coworker and his wife moved there. She teaches at the college there -- CO School of Mines -- and he works for an electronics firm.

They own a smart car. Don't know the color.

Sincerely,

Macster.

Dennis C

Thanks Macster. We're actually going to live in Evergreen, just a little past Golden up in the mountains. We're really looking forward to getting out there.

Dennis C

Headed to the shop on a flatbed truck... not the best way to start a Monday morning.

Dave!

I see your car is wet, if it was raining all weekend I would guess cracked coils. Had you already ruled that out as a possibility?

Dennis C

I haven't ruled that out. It was raining all weekend, including my drive home from the office on Friday.

My local Porsche dealer was booked all day today, so they won't give me the diagnosis until tomorrow.

Dave!

Yeah, ten bucks says it's your coils. Your engine was hot and dry in a cold and wet environment, going to pick up a lot of moisture and condensation.

wanabe911 owner

any word?