tappet solenoid brackets look fine, the plug look a little dark, probably from me repeatedly misfiring it (after switching coils around). I don't see any cracks so far in coils. Time for swap.

Going to be swapping 1-5, 2-6, and 3-4, and switching over to NGK BKR7E's and see what happens.

Thanks again everyone for their help, i'll report back here in a few.

 

for the record, every dead coil I've replaced( a lot)-have never seen one cracked...always fail internally
I'd just buy a complete new set of Beru coils and 'GT2' spec Bosch 7410 plugs...
Cam act. brackets look like crap, replace.


CHECK THE CONNECTION AT THE COIL! P.O of my car had a 'renown' local Pcar shop do the coils/plugs, spark miss=coil connector not fully plugged in...

 

my last coil change saw one visibly cracked. car ran as one would expect. it stuttered.

 

well...after the swap, i'm having the same issue and the same p0301 cylinder 1 misfire. the coils snapped each time, i made sure to be extra cautious about that.

What's next? Injector swap?

 

yes looks like it

 

The brackets are cheap so agree it couldn't hurt to replace but he said coils only have 3000m so they should be fine. I would clean all connections with electro-clean and add some injector cleaner= has worked wonders in the past for me but who knows lol.

 

I have a bottle of techron fuel injector cleaner ready to run, but not really that excited to drive it (until the tank is low) when i can't get into boost :/

 

to clarify, you just(now/today) swapped coils/plugs with no luck?
have you pressure tested the intake manifold yet?... complete waste of time swapping injectors(big job) without doing a pressure test first(simple)...

 

I'll do that next . I need to build my own piece if I want to test off the throttle body though.

 

absolutely, as 32 has just suggested. i'm back with ANYthing related to spark and fuel as in the beginning. so injectors would i suppose be the next logical item to eliminate as the cause. but robs point should not be overlooked. testing is key and a lot easier than opening everything up.

this thread had me techron the car myself yesterday, so thanks for that. we all share your pain.

 

Wires crossed indeed.

Could be a boost leak but local to the #1 cylinder. I don't really like this but you have to be sure.

OTOH, I note you are running a tuned engine making 1.2 to 1.4 bar boost. That's quite a bit over the stock engine's boost. A boost leak has to be a real possibility.

You've pretty much eliminated plugs, coils, at the #1 cylinder and at adjacent or opposite cylinders.

I don't know about the fuel rail filing.

You haven't tried swapping injectors. I don't think the injector will prove to be the source of the misfire, but I could be wrong.

Before you do that I'd suggest you pressure test the intake system to eliminate a leak.

Trying Techron at this stage? Not sure I could go along with that. The misfire seems too persistent to be attributable to something Techron can help with. Also, I prefer to when troubleshooting something like this to avoid running the engine any more than necessary to avoid possibly doing collateral damage. To get the benefit from the Techron you'd have to run the engine drive the car enough to perhaps go through a tank of fuel. That's around 200 miles.

I'm still leaning towards a burnt valve or an intake valve lifter that doesn't proper switch from high lift to low lift or doesn't switch from low lift to high lift. But of course, I hope you find some other less serious explanation and my suspicions are proved wrong.

As I think I touched upon in another post there is a large section in the Turbo factory manual regarding persistent misfires and the steps necessary to track down the source. Some of these steps involve road testing the car while monitoring the engine's telemetry to confirm the low to high lift/high to low lift switchover occurs correctly.

My point is my suspicion is based upon the fact the factory went to great trouble to document the testing for what must be a very real possibility when other more common reasons for persistent misfiring have been eliminated.

For the burnt valve there is the compression test.

Oh, blaming the misfire on the DME is like blaming it on the wiring harness. It is easy to assign blame but before replacing the DME I'd have to have conclusive proof the DME was at fault. Like the wiring harness the DME is a pretty expensive piece of kit and replacing it is not something one does generally. I mean there is throwing parts at a problem and then there is throwing parts at a problem.

Besides, it doesn't really read like the DME (or the wiring harness) is at fault. The behavior is not as consistent as I would think it would be were the harness/DME at fault.

I hate to belabor this, but before I tossed a DME or wiring harness at the symptom I'd seriously consider a compression test. But as I have mentioned more than once you should discuss this with a trusted Porsche tech to see if he agrees with this. He may not. But if he doesn't then he must offer something else to look at, to try.

 

^ that seemed all good advice. but i have never had a boost leak result in a "stutter". is my experience uncommon? any leak i've ever had merely resulted in lack of boost with or without cels. but always there are codes. i agree also that going for the ecu or even harness is premature and sky is falling even at this stage. but the qualifier being i know very little beyond what has occurred to me and any attendant fix.

is he really at the point where are compression test is advised!? though a pressure test,.. everyone should have one of them home depot diy jobs, or have a bud who does.

there's a diy in here on how to make them for those capable/inclined. sounds like the op can handle it. it isn't complicated thats for sure.


one last thought re "throwing parts". plugs and coils on tuned/modded cars should NEVER be considered as thrown parts lol. or throw them frequently. take your pick.

 

what i posted was verified causes of the specific misfire. 3 cars at the shop i use needed a complete harness rebuild and scsponger from here needed a dme after gmg racing spent countless hrs of labor changing everything from plugs to turbos. to me it reads EXACTLY like an electrical problem as no matter what the op does the misfire stays at the # 1 cylinder. the only thing left at this point is an injector swap to see if it moves the misfire. boost leak testing is fine but that seems very unlikely to affect a single cylinder. as for a compressionntest i said before its fine to do but this isn't a ongoing issue. it ran fine one day and misfire the next. unless there was a catastrophic event (and i would bet you could hear that ) its not compression related

 

IIRC the coils and plugs are fresh. They are fresh because it was time to freshen them. And a misfire is just further incentive to do this. I do not consider this throwing parts at the symptom. If my reading comprehension is still working reasonably well, I believe the OP has swapped both plugs and coils around enough I think that if it were one of these the misfire would have appeared at another cylinder or at least gone away at the #1 cylinder.

I would consider it throwing parts at the symptom if the OP replaced the plugs or coils again without more evidence these, well, at least the plug and coil at the #1 cylinder, were responsible for the misfire.

A pressure test is I believe rather easy to do. It should be easier than a compression test. I'm not convinced there is a pressure or intake leak but Turbo's blowing a lot less pressure than 1.2 to 1.4 bar have had their share of pressure or intake leaks.

A compression test is advised when the only explanation has to be from the cylinder's integrity, that is from the cylinder being suspected of not holding pressure. Now I say when the only explanation has to be the cylinder's integrity but that doesn't mean the compression test will turn up a bad cylinder. If the cylinder and the adjacent ones check out OK, this is a sign something else was overlooked or something else is at fault.

If you don't think a compression test is called for at this stage, then what do you advise? Replacing the plugs and coils again? Replacing VarioCam solenoid brackets?

Checking out the wiring harness is a possible course of action, but it is a fair bit of work. If one is not careful he can static discharge into the harness and all wires in that thing lead to the DME.

There there is the DME. Ok, the DME has to be considered if other possible explanations are scratched off the list. Again there's the risk of damaging this if one isn't really really careful.

I mean if the finger of suspicion points at the wiring harness or the DME then these have to be checked and eliminated. I won't argue that point. But I would not tackle the harness or the DME until those were the only two things left.

If the OP decides another round of plugs/coils is called for well, that's his call. If after this if the misfire remains if he wants to delve into the wiring harness or the DME that's also his call.

Added: I went back and read the initial post, and while the coils and plugs are fresh, they have 3K miles on them. To require replacement again at just 3K miles would be exceptional, but as I have noted a couple of times the engine is making 1.3 to 1.4 bar boost. This is nearly double the stock boost level. It could be possible the plugs have gone off just enough. Or a coil (maybe all the coils) are just not quite up to the task of firing a plug in a chamber with 1.3/1.4 bar boost. The #1 cylinder could be quite healthily otherwise but just a shade down from the other cylinders and at these extreme boost levels could be the most sensitive of the cylinders.

Thus I could go along with another round of new coils and new plugs. Not sure if there are any aftermarket coils that are better able to handle over boosted engine spark needs. As of the plugs I'd be darn sure I didn't compromise on these either. Now is not the time to see how low quality plugs one can get away with.

 

I don't doubt you regarding the wiring harness business. If that's what's wrong then that's what's wrong. However, I don't believe the OP has exhausted all the possible explanations yet.

And moving ahead with a wiring harness rebuild is going to be an expensive undertaking. I would need to be very sure this was what was needed before doing it.

I agree the boost leak test will probably not turn up anything. But I'm not sure I'd skip it.

As for the running fine one day and not running fine the next this happens a lot with these (and other) engines. Generally everything is fine until it is not.

For the misfire to appear out of the blue doesn't require anything catastrophic. The OP is running 1.2 to 1.4 (or was it 1.3 to 1.4?) boost. That's a lot of boost. Combustion chamber temperature and pressure is going to be very high. Exhaust valves already run quite hot when the stock engine is working at full load. These can be dull red from the heat. Now double the boost and don't tell me you can't believe over time this could possible cause a valve to leak? And once the leak starts a tiny notch will be burned into the edge of the valve and at some point the cylinder will misfire because it can build pressure.