digitalsam

Driving 03 CS4 home from a track event this evening, the check engine light came on and the engine felt jerky and rough, especially when driving over 50mph . I got the car towed home.
Codes were;
P3000 Random Misfire Detected
P0301 Cylinder 1 misfire
P0306 Cylinder 6 misfire
The car has little over 55k miles. Any ideas what is causing these codes?
I appreciate your help

KrazyK

Are your serious that you dont get the connection?

Macster

A CEL with the engine running poorly is generally not a time to take up DIY engine diagnostics.

Without knowing the history of the car all I can offer is the obvious: Coils/plugs.

But there are other causes too. In one case a bad MAF was triggering misfires and just one bank too.

Unless you are prepared to get your hands dirty my advice is to tow the car to a qualified Porsche shop (dealer/indy) and have the misfires looked into.

digitalsam

Thank you for your reply Macster. I wasn't planning on doing the work myself, however just educate myself on the possibilities. The car has little over 55k miles. Last CEL problem turned out to be a nightmare (https://rennlist.com/forums/996-foru...-opinions.html)

One think I forgot to mention is that the CEL was flashing. Also, I find it little odd that the problem is happening on cylinder 1 and 6 that are on different sides. Any opinions on that?

Imo000

Since mechanic will be fixing it, there really is no point guessing what it might be. I could be a dozen different things.

KrazyK

Flashing CEL after track event is a clue.

Macster

About the only thing I can maybe take away from the misfires on both cylinders 1 and 6 is is that the problem might be a common failure, common to both banks. Maybe.

I did read the link you provided and I then recalled the what you went through before. What a nightmare. But the cause of the problem was found. However, I do not want to dump more gloom on you in your situation but I just watched that video for the first time and I was left wondering why the cam developed that flow problem? Was the cam bad or did something make it go bad?

Anyhow, IIRC the plugs and coils are I guess new, or new enough that they can be moved down the list of possible things to consider, though I will say that marginal coil connections at the wiring harness has been known to cause misfire grief.

Since you are not going to tackle this yourself time to get the car to your favorite shop and get the car on the road to good health.

Macster

Maybe.

Maybe not.

What would you say about all the car owners who have reported a flashing CEL without having just left the track, some have never been to the track? It's their imagination?

Come give the poor guy a break. His engine's sick, possibly seriously sick, though I hope I'm seriously wrong, and it turns out to be something relatively minor.

KrazyK

Mac, I know your trying to think positive but flashing CEL w/misfire on both banks leaving track? I think we know where this is going. I hope hes not still running the engine. I agree he needs some pro help.

digitalsam

Macster, regarding the cam, my mechanic thought that the problem was a poorly constructed cam, bad quality control, etc. The cam ended up collapsing, which eventually led to the blockage.

The 60k service hasn't been performed yet, it was to be done this summer. So the spark plugs are relatively old (changed at the 30k service). As far as the coils, I think they the original.

digitalsam

KrazyK, can you share with us what you think the problem is. You keep mentioning the track, but I know that there are lot of people on this forum who track their Porsches, and haven't had this problem.

I am hoping to keep the focus of this thread about the mechanical problem, but I can tell you that my track event wasn't exactly a race, but a PCA DE event. Porsches are built to be performance driving cars, and they can withstand some spirited driving, don't you think?

It is very possible that driving on the track could have contributed to the problem, but the CEL came on at ~ 20 miles after I left the track, on the highway, where my avg speed was probably higher than the track. (It was a slow track!)

Macster

Well, with the plugs having some miles on them and the coils being probably original then that provides a ray of hope the misfire cause is related to plugs/coils.

Given what ultimately turned out to be the cause of your engine troubles a while back I was not looking to get pulled into a quagmire of trying to offer any help regarding misfires causes.

Anyhow, I'm thinking -- hoping anyhow -- the track time extracted the remaining life from the plugs and coils. But your trusted mechanic will have to make this determination.

Ubermensch

I'd look at the coils and plugs, and then the AOS. If the AOS is failing and blowing oil into the intake you'll get misfires and rough running. Many track rats run oil slightly below full to avoid pulling extra oil into the air stream.

Regarding Krazy's comments: "E' meglio vivere un giorno da leone che 100 anni da pecora" (it is better to live one day as a lion than 100 years as a lamb).

halik

Flashing CEL is not a good sign, the misfire counts in the measured time interval kept increasing, so you were likely running on 4 cylinders. Hopefully it's just bad coils - any issues with oil pressure?

halik

Clue of what? Dropped coils? Bad Maf? Scored cylinders? Internal damage? Electrical problems due to all the vibration? Exactly what does a track even clue you into?

Low oil pressure on the gauge after a track event is a clue; cel tripped by misfire counter can be a million things, regardless of where the car has been.