Thanks, don't think I even have a torque wrench that goes down that low

 

Xmas is coming soon :-)

 

It is either a coil, a plug or you have a vacuum leak somewhere on the intake - I just went through this on my 996 and it turned out that I had split an intercooler - gave me the same codes and ran terribly.

It is becoming very apparent to me, that these cars do not like vacuum leaks and these leaks can cause other seemingly unrelated codes to appear.

 

It's going to be a bummer if after changing plugs and coils its a vacuum leak. You split an intercooler or intercooler hose?

 

Well, at least you have it apart...

You should be able to change the coils/plugs and then do a pressure test and listen for leaks - no leaks detected, put 'er back together and enjoy. I was thinking that it wasn't apart, this will make it much easier to check.

 

On your 996 you were getting a cylinder misfire on the same cylinder with a vacuum leak? Did you split a hose or a hole intercooler?

 

On my 996 I actually split an intercooler core, which made it incredibly hard to trace. My visual inspections showed nothing wrong, everything was connected. It wasn't until I disconnected the output side of the turbo and put about 20psi into the closed circuit could I identify the problem with the intercooler. One of the issues was that the misfire was seemingly random - it moved from cylinder to cylinder and it went away (completely) when you drove it - only at idle did it sound horrible and throw codes. It also had an interesting side effect - at about 2k rpm it would in fact hold the car at a constant speed like a for of cruise control - I suppose that was the natural 'balance' between the throttle body and the split in the IC.

 

Harbor Freight here I come.

 

Update, new plugs and coils are in and so far no miss fires. I think if I had to do it again I could knock it out in one day. Number one and four cylinders are the hard ones to get too.

 

DUPLICATE

 

I just picked up a misfire code as well... Car went into limp mode, lit up all the warnings (First engine fault, then PSM, PDCC, 4-wheel drive, all "drive on carefully"). Off/lock/wait/restart didn't clear codes.

After Dealer says problem with coil pack. Full 60K service was done less than 3K miles ago with new plugs, but presumably didn't put in new coil packs (stupid. It was before I owned the car, dealer prepping it for CPO which it has).
Codes where:
P0301 (Cyl. 1 Misfire)
P2302 (Bar ignition module on cyl 1, soft shutdown).
(and a course a bunch of others, but I think these are the relevant ones)

Also waiting to hear if coil packs are "wear and tear items as defined by PCNA". Kind of sucks, the coil packs themselves are not that expensive, but dismantling the rear of the car for access, which THEY JUST DID for the 60K service, is quite a few book hours. There is no "scheduled maintenance" replacement for the coil packs.

After dealer pulled codes, they said they were going to reset them, but when I got back in the car the codes were still present. So either they reset the codes and they reoccured almost instantly or (my theory) they didn't actually reset them even though the service writer said they did. I

I reset them myself when I got home, and so far, at least on a short test drive, they have not reoccurred.

Sigh... This is why I do most work on my cars myself.






Has anyone ever seen an official list of "Wear and tear items defined by PCNA "? Sure, brakes, tires, wiper blades, clutches and spark plugs are obvious "wear and tear" items. I personally wouldn't consider coil packs to be "wear and tear", and they are not a "scheduled maintenance" item, and IMHO a coil pack failure under original or CPO warranty *should* be covered. Service manager wasn't in, so I won't hear more until Monday.

 

Mine was cylinder 4. I saw some where that dropping the motor is what it calls for, I could see it make it a little easier. I don't know how involved dropping the motor a couple of inches is though.

The hard part for me was the heat in San Antonio while working on it.

 

I've done coils and plugs on a 996 Turbo several times... Quite a bit of work, but not terribly difficult. Sounds like the 991 Turbo is very similar, but perhaps just a bit more difficult.

But I will be more than a little irritated if it is not covered under my CPO, especially since they just did a full/major service ~3K miles ago.

 

its been a long time since I had my 996 Turbo, but I remember it to be way easier.