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Hello All,

I purchased a 2005 Carrera base with 60k a few months ago. Being a Porsche fan all my life, this was finally my first one. The car fax and records looked good but since I got it, its has been nothing but problems. Within the first month, the water pump went out. Considering the car is 7+ years old, I was okay with that. The following month the CEL came on with misfiring sum and all cylinders. I took it to TPWS in Austin and they said I needed to replace the spark plugs and coils so I had them do it. Now 2 weeks later, the CEL is on again with misfiring sum and misfiring 3, 5 and 6 cylinders. I made an appointment to take it back to TPWS. I don't mind replacing my coils and plugs but it seems like that wasn't the root cause of my CEL to begin with. Questions to the forum:

Should I expect to have my 911 in the shop every month (i. e. is this normal)? Shop always seems to be really busy.

Is going through a list of possibilities the correct way to approach these CEL codes or should I take it to someone else?

Thanks in advance,


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  • Admin

Odd that there is no misfire on cylinders 1,2, and 4 currently.

Are they sure their are no other codes?

Here are some possibilities:

When misfires occur on both banks:

- Incorrect/low-grade fuel

- Tank empty

- An engine-block heater is used

- Secondary air

- Exhaust system blocked/narrowed

- Foreign bodies in intake tract, this can lead to sporadic misfires on changing cylinders

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Checking the codes myself using Durametric. Thanks for the info. I will see what they say when I take it in on Tuesday.

Funny, I don't see plugs or coils in your list.

I've been using the highest grade Shell gas from the same station since I got it...maybe I'll try a different one.

About the engine block heater...I've noticed a burning plastic smell from the engine when it's hot. Would that correlate to the issue with the engine block heater?

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It would be quiet odd to have all the spark plugs or all coils go bad at one time (it just does not happen that way) - so with misfires on all cylinders (to start) would steer me away from plugs and coils.

Water in your gas?

Bad gas?

Any recent changes to the intake or exhaust?

If you had a block heater then you would like see a plug hanging down for it. Is the car new to you?

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  • I hope you get to the bottom of your problems.. And just to put your mind at rest the cars are incredibly trouble free as long as you keep up the scheduled maintenance. I have had 4 now and only one was a problem. But I never should have bought it (because I knew it had issues) so that one is on me.

Totally agree with Loren .. The coil packs dont all go bad at once. If this shop cant help you perhaps you should see another tech..

Good luck!

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Didnt some of the early cars have problems with the grounding cable? I think it was even a recall or a TSB. Could that be it? Have the battery checked too, these cars don't like weak batteries.

Water pump, is very very common for the mileage.

I went from a bomb proof 996 Turbo, to a 997 Carrera S. Then afterward came across a 60 page report about all of the design weaknesses these motors have. I came close to selling the car the very next day, it made me so paranoid.

But I did not. I added the Porsche 3rd radiator kit (Porsche kit, sold by Suncoast for really reasonable) and added aTungsten Disulphide oil additive, changed the thermostat out to a cooler unit that starts circulating coolant sooner than the stock unit. And I drive it almost daily. Now has 82k miles and no smoke on start-up, burns very little to no oil.

So I say this to give you a small heads up that there can be some major problems with these engines, but if treated right, and you stay observant to some things and service the car more than Porsche recommends, it should be fairly problem free.

I've noticed in the past on two Porsche's that I bought that didnt have a lot of miles and hadnt been driven a lot, that when I started driving them daily I had a few quirks develop soon afterwards. Fixed those quirks and the cars remained fairly trouble free.

I honestly think the more you drive them the more reliable they are. Letting them sit, and then driving them every once in awhile I think leads to little quirks and problems.

Send me an email if you want the report...it may scare you, but its good info. to be aware of, so you can recognize any of the major problems if they start to develop. Dustinr@nvbell.net

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Thanks Dus10R. Send you an email in a minute.

So the shop couldn't find anything wrong.

Repair order: They performed diagnosis of faults with PIWIS, performed short tests, verified my MAF sensor was good, no misfires or rough running in multiple test drives and no reocurrance of faults.

Maybe it was just a batch of bad gas...I'll keep monitoring it. Thanks everyone.

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  • 2 weeks later...

I have the same issue... random misfires on all cylinders

Was told by the indy shop that the misfire sensors on the early 997's were too sensitive and there was a TSB to widen the CEL range.

Anyone know if this is true ?

The car runs great and smooth otherwise

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Update: So my 911 has been running without the CEL coming on this month. I have been reading that report Dustin provided and will probably opt to add the 3rd radiator kit.

Dustin, where can I find a similar thermostat as the one you installed on your Carrera S?

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Update: So my 911 has been running without the CEL coming on this month. I have been reading that report Dustin provided and will probably opt to add the 3rd radiator kit.

Dustin, where can I find a similar thermostat as the one you installed on your Carrera S?

Pelican Parts sells them... as I'm sure a bunch of other places do as well. They are called "Low Temperature Thermostast" they start to open at 160F instead of 181F

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Update: So my 911 has been running without the CEL coming on this month. I have been reading that report Dustin provided and will probably opt to add the 3rd radiator kit.

Dustin, where can I find a similar thermostat as the one you installed on your Carrera S?

Pelican Parts sells them... as I'm sure a bunch of other places do as well. They are called "Low Temperature Thermostast" they start to open at 160F instead of 181F

The OEM stat starts to open at 186F, and is not fully open until well north of 200F..............

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  • 2 weeks later...

I have mine (997.1 C2S) for 2 years now with some minor problems such as watch pump, oil level sensor, door lock, etc. which has all been solved, no problem so far and I think once you have resolved the problem, it will be a nice ride for you, so don't let these problems stop you from enjoying the car. My previous 996 3.4L litre has more problem than you could expect but I still enjoy it the moment before I sold it.

As a Porsche fan since I was a kid, I have had 2 so far (996 & 997) and I have driven my friend's 993 C2, I must say as a sport car, daily ride, 997 is the best I have driven so far. Of course, new 991 is even better (I have test driven one last month) but the price tag is way too much.

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Thanks Eric. So my first 4 months of owning it, I have had to replace/change the items below. Any other parts I should be concerned with for an '05 997 with 66K miles?

Water pump replaced

Thermostat replaced

Belt replace

Spark plugs and ignition coils

Brake fluid flushGear fluid changeFront and rear brake padsCoolant tank replaced

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  • 4 weeks later...


Did you have a PPI done prior to buying it? I'm just curious. Seems that some of those things you had to replace could have been flagged.

I recently bought an '08 997 and the PPI turned up some maintenance that needed to be done but at least I knew that going in.

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No, unfortunately, I did not get a PPI done before the purchase. It was a "let's go take a look at this car" scenario with me ending up driving it home. The records reported everything current including the 60K done but definitely a PPI would have helped. Anyway, it's been smooth sailing so far. Now I'm finally seem to be enjoying the car. Congrats on your recent purchase, btw CA_Boxter.

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