Stuttering, Stalling 997 CS

[jaysickler]

I purchased one of the first 997 CSs in Portland in November 2004. I have 8,000 miles on the car. I've had nothing but problems with the car stuttering, lurching and stalling from a stop. The problem is not always present and goes away after a few minutes of driving. It doesn't seem to be related to engine temperature, external temperature or gasoline used. I've driven M3s for the 8 years leading up to buying this car (my first Porsche), and have never experienced this before. After the first few minutes the car runs just fine. But I have to really feather the throttle and give it more gas for those first 3 minutes. I've stalled it a number of times pulling out in front of traffic. Very dangerous. And when it stutters and jerks it can be pretty violent (with sometimes a loud "thwack/thunk" from the engine). I first thought it was my driving abilities, but if that was the case the stuttering would happen all the time not just the first few minutes. The dealer (Sunset Porsche) and PCNA have not been able to fix the problem (which they think doesn't exist) and are not willing to replace my car (which is all I've asked for). Their attitude is basically live with it, we are not going to take care of you. Please help me if you can, as I had nothing but the runaround. I'm very frustrated. You expect more from a car that costs this much money.

p.s. I'm also only getting 11-12 miles per gallon. I drive spirited, but not like a mad man. Is this a common experience? R&T got 16.2 mpg when they tested it and I'm sure they ran it harder than me.

[Loren]

Replace your car? I've yet to see a problem that can't be corrected.

Tell us more about the history.

6 Speed or Tip?

Any mods to the car?

Has it been doing this since day one?

How many attempts has the dealer made?

Did they keep the car and drive it for a few days?

What have they replaced?

Did their shop PIWIS tester show any codes?

[jaysickler]

Replace your car? I've yet to see a problem that can't be corrected.

Tell us more about the history.

6 Speed or Tip?

Any mods to the car?

Has it been doing this since day one?

How many attempts has the dealer made?

Did they keep the car and drive it for a few days?

What have they replaced?

Did their shop PIWIS tester show any codes?

This car is a 6-speed

No modifications

Performing badly since at least early '05

Attempted to repair 4 times, kept it overnight a couple of times, no codes showed up in testing, and nothing's been replaced

They don't know what the problem is but have even admitted to me that they have had other similar complaints

[djantlive]

You left the car overnight and they were not able to reproduce it? Why not leave it overnight and have the tech drive it with you in the morning? Also, try different dealer. It'll be hard to deny the problem once dealer is able to replicate it.

[Loren]

I asked around with some folks here (shop foreman and independents) and they say that the NW US has had a lot of contaminated gas for several months now.

Here is a suggestion... Buy some Shell premium gas then add a can of HEET Gas-Line Antifreeze and Water Remover. The HEET will remove most if not all of water in the gas tank. You should be able to find HEET at Autozone, Pep Boys, Kmart, etc., etc.

What have you got to lose?

[jaysickler]

I asked around with some folks here (shop foreman and independents) and they say that the NW US has had a lot of contaminated gas for several months now.

Here is a suggestion... Buy some Shell premium gas then add a can of HEET Gas-Line Antifreeze and Water Remover. The HEET will remove most if not all of water in the gas tank. You should be able to find HEET at Autozone, Pep Boys, Kmart, etc., etc.

What have you got to lose?

Thanks for the advice. I've now run the proper proportion of Shell gas and Heet through my tank. No change. This has been going on for a lot more months than just recently. I've used all the major brands, Shell, Chrevron, Unical (I don't use Arco). No difference. I don't believe it's the gas. If it is, why isn't my wife's BMW M5 having the same problems? This is a Porsche problem that no one can solve.

[Loren]

I do not understand how your car can run with a stutter and stall and not throw a fault code. If there is any misfire in these engines they will throw a pending fault code(s) that, even though it does not turn the CEL on it is recorded in the DME and can be read with the Porsche test tools.

The three things I've heard of that could cause this problem (on a new car) are: DME cable not fully connected (happened to me), a bad DME, or fuel pump that is intermittently not holding pressure.

[JimB]

When this happens, will the car idle or do you have to feather the gas to keep it running? If you won't idle, you might look at the variable valve lift connections. The symptoms sound about right.

In simple terms, your car uses a different amount of valve lift at idle and low rpms than once you get going. I think this is just a smog deal. Your car will not idle unless the computer is sending a positive charge (12v?) to both cylinder heads. If you have a loose wire, corrosion or a confused computer you could be having the problem you described. I would think you would get a code but who knows. Just an idea.

Jim

[faterikcartman]

Agree with some advice above.

Talk to the dealership (to make sure they don't tow you) and park the car there Friday after work. Let it sit all weekend and then show up monday when the service department opens (don't leave them the key (though I guess they could cut another) if you think they might sneak out and warm it up), probably at seven or eight in the morning, and grab a tech and ride with him as he tries to drive it around the block. Repeat until it happens while they're there. Plus, after it happens bring it in and ask to see the fault code history before they reset it. Try a brand new dealer for this experiment so they may be more willing to work with you than saying you're nuts.

[caveman]

chefman, I'm working with the same dealer on a similar problem. At least with my car, the check engine light comes on when the stuttering and misfire happens. Dealer had the car 4 or 5 days before they saw the misfire and check engine light come on. But same as you, they are stumped as to cause or cure. They had previously thought it was the variable cam solenoid and replaced it, but the problem reappeared about 50 miles after that.