deilenberger

You're getting too many codes now for it to be coils unless the coils you're getting are total rubbish. I'd have to suspect the wiring between the ECU and the coils, or the ECU itself. One thing about misfires - strangely - when a coil goes bad on a cylinder something often seems to happen to the spark plug it was supposed to fire, making it difficult for it to fire the plug. My suggestion would be - new coils and new plugs - if that doesn't fix it - then the ECU and wiring are the next places to look.

MisterMisfire

The car is going in to an independent Porsche/Audi garage so I will let you know what he says. But I am inclined to agree with you about the electrical/ECU fault. Nothing else makes sense. I just took it out for a drive and within a mile the CEL was on - only one code - P0306 so it is the 6th cylinder again.

My guess is that it is a dry joint or a cracked wire between the ECU and the coil pack. How they check for that I don't know.

But it definitely is not coil or plugs. It isn't fuel pump. It may be the injector if it has a piece of crap in it and causing it to squirt instead of spray.

Will find out tomorrow evening....

And to add to my woes there have been 2 nails found in 2 tyres in the last 2 weeks!

MisterMisfire

Right, just got back from the garage. The engineer showed me the live readout from his diagnostic equipment which showed straight away a misfire in cylinder 6 - but also a smaller number of misfires from every cylinder. With jerky pumping of the accelerator the misfires on 6 rapidly rose to about 180 whilst the other cylinders came to between 10 and 45. Once the car was at steady revs of about 3000rpm then all misfires disappeared. Every one of them was at zero.

He did a smoke test under pressure and found a small vacuum leak in a breather pipe but doesn't think it is major enough to cause all of the misfires.

I told him the timing chain tensioner was replaced and he thinks it may need adjusting.

They're keeping the car for the first few days of next week. Will replace this breather pipe and see what happens.

Any thoughts from folk out there?

MisterMisfire

I still haven't received the AOS diaphragm but he is interested to check to see if it that. He has warned me that there is a high chance of him snapping the plastic cap as he removes it - I hope not at that one piece is stupidly expensive. Hopefully it arrives soon and he can fit it for me. But like I said, if anyone has any ideas about these misfires I am all ears....

Rod Croskery

Maybe your bargain coil packs are no better than the set of eight from China I fought with last week. Four of them would not work.

Try some tape on that hose before you pay $182. for a new one.

If you spray the ends of the hose with WD40 they become a little easier to compress and remove but don't bend the hose.

MisterMisfire

Seriously $182? That is bonkers. The garage are good. They don't waste money so they'll buy a less expensive oil filter or air filter. But something like this pipe they'll buy Porsche with the idea that they might create a problem that doesn't exist (or mask a problem that does exist) if they use another part.

Friday the 13th......was hoping for some GOOD luck. Currently driving a VW Polo for the next 4-6 days!

MisterMisfire

Okay, the latest from the garage is quite serious - suspected timing chain problems. Looking like 15 hours to remove the engine, strip it down and locate the problem and I am told that the cam shaft may have worn in places. They reckon the minimum bill is 1000 pounds and more likely to be 2-2,500. It simply isn't worth doing so I've told them to get it back on the road and I'll be popping down to a dealer sometime soon to try and part-exchange it for something else.

Really gutted!

Rod Croskery

Very sorry to hear this. Are you sure it's not an electrical fault? Have you pulled up the carpet to check for moisture and corroded wires as Deilenberger suggested?

deilenberger

These aren't known for timing chain problems - at least not the US model V6.. why was the timing chain tensioner replaced some time ago? Normally that lasts the life of the vehicle. If it doesn't - usually something is wrong with the chain causing the tensioner to fail.

MisterMisfire

I called the garage this morning and they said that they have a service whereby they can call a Porsche helpline to run through things and it was a combination of the helpline and the engineer's view of things that led them to the timing chain being the problem. I had the car looked at by another garage a month or so ago and they said that the timing chain tensioner was worn and needed replacing.

I never saw the worm part.

I asked the garage this morning to look under the carpets and they said they would and get back to me. I really hope it is a dry joint or a corroded writ.

I just don't understand how it can drive perfectly on one ignition firing but then be a complete dog on the next.

These intermittent faults are so hard to track down. That said, this misfires more than it runs well.

And the fact that there are no misfires when the car is running at 3000rpm. I just don't get it.

I've pointed the garage at a potential electrical issue and hope they find something easy and cheap to fix.

MisterMisfire

Garage haven't looked under the carpets. They're convinced that the Porsche technical helpline is right and that it's a timing chain issue. They've not looked under the carpets as they say they've got to take the seats out.

I saw a guy had posted on here some photos of his efforts to expose the wires and it didn't seem to involve seat removal. Anyway, I might look at our this weekend but I can't see how this will make one cylinder misfire a lot and the others misfire a little...

Douglas61

Have you tried to look at it with a durametric?

MisterMisfire

No, I don't know anyone with a Durametric. Current situation is that I'm driving it and it's sluggish. I've got a Bluetooth OBD2 reader in it and an app in my phone. The P0300 is coming up all of the time, and usually with P0306 so it's a random misfire and pot 6 is the worst offender. Yesterday on the drive home I noticed that the vacuum dial in this app was fluctuating between -0.5 and -24.0 but stayed mostly in the negative. One one occasion it surged into the positive.

Something to worry about?

On a positive note, I bought the car on a credit card and I'm going through my credit card company to recover the estimated £3000 cost of putting this car right.

Fingers crossed that it works out!

Douglas61

I think it is a good idea to recover the estimated cost for repair first. What do you mean by "sluggish", engine shaking? Does it happen when running idle?

MisterMisfire

It's not greatly noticeable, but yes the engine is shaking. Once you get to 3000rpm then it stabilises. It has to do a gear when traveling at 65mph and you hit am incline - it struggles like hell. It's just rough.

The engineer told me that the timing chain has worn (they don't stretch, contrary to common belief) and may have slipped a tooth on the cog. Once they get the engine out they'll be able to see what the state of the cams is, but they're predicting that there will be uneven wear which will result in them needing replacing.

An expensive job, but one which the dealer should have addressed prior to selling the car. He's being a slippery fish, so I just hope that the credit card cover will sort it out.