Hey guys,
I'm hoping someone can lend some advice as to how I can chase down this p0301 misfire code. It started when it was below 40 Degrees for the first time mainly under high boost (1.3-1.4 bar) but occasionally happens at partial throttle when the engine is cold coming out of my neighborhood uphill (not sure if the details matter or not). My setup was running fine before but then out of nowhere this started happening, nothing was changed in order to cause this which leads me to believe a part is failing.

Before I installed the k24/18g's I changed coil packs and plugs (3,000 miles ago) with the 997 beru packs and bosch fr6 LCD per EPL's recommendations (who's tuning the car). I have a brand new MAF and brand new 02 sensors all the way around. I'm running 72lb EPL injectors and stock fuel pump. I swapped out a coil pack with an older unit I had laying around, both passed the visual inspection but the missing / stutterring at high boost continued. I then swapped out the suspect plug for a NGK fr6 plug (nobody local carries bosch) and still have the same issue, possibly worse. I don't know if i should spend the $40 on a new coil pack just in case and buy a new fr6LDC plug just to be safe, but i hate throwing money away.

I've read that the next items are injector, fuel pressure, or air leak somewhere. I don't smell fuel, I don't see any leaks (although it's tight in there to look around), and don't think I could be hitting that high of boost with an air leak. I could try and swap injector 1 to injector 2 to see if the code followed the suspect injector but I'm not looking forward to that day for the amount of work it would take. Is there anything else i can check or a way to tell exactly what's causing the misfire? I suppose I could swap a coil pack and plug from 1-2 and see if it follows but what are the odds I had two bad coil packs in a row (when it never misfired with old coil packs).

I'm open to any advice, just would like to get this resolved before the snow comes down heavy and I can't really test anything. Thanks in advance!






edit: update 12/14/14 : swapped in new injector and resolved issues. Will report back in a few weeks to make sure stuttering is completely gone. Also swapped in new fuel filter. Will need to wait for EPL to confirm injector was at fault.

 

ngk doesn't make an "fr6" plug. thats the wrong heat range for an ngk ( 5 iirc would be stock ). you need a bk7re BUT you shoiuldnt mix plug type but that isnt as bad as mixing diff heat ranges. the bosch fdc 6 is the heat range 7 for the ngk, always go one step colder on a tuned car eg the bosch 6 yuor tuner installed,

 

thanks for the tip ; I was simply trying to rule out the possibility of the plug going bad. does the plug look bad? should I order just 1 replacement bosch to rule out that or is there something else I should look for?

 

A low battery that that will still start car etc can cause that code but I would suspect vac leak.

 

car stays on tender whenever it's in the garage. the car typically drives fine until driven hard under boost, wouldn't vacuum leak show up under low boost / no boost?

 

you're doing some things that will ensure you have issues, namely mixing old and new.

i would begin anew with the bosch or beru coils ( doesnt matter which! ) and all new plugs the bosch fdc 6 ( for gt2 )

it that doesnt eliminate the codes or stuttering? then something else might be amiss.

but you cannot diagnose/correct issues by mixing old and new ignition components. this i promise is true. i'd start fresh ( though its a hassle ) and see what happens. good luck!

 

I'm trying to avoid dropping the $300 on new coils and plugs just to 'guess' if that's the issue. The coils /plugs only have 3000 miles on them.

 

What would a shop do?
A code P0301 may mean that one or more of the following has happened:

• Faulty spark plug or wire
• Faulty coil (pack)
• Faulty oxygen sensor(s)
• Faulty fuel injector

So if it only happens under boost, is one or more likely? I'm thinking injector as it pops up when the demand for fuel is at its highest. kenny

 

I know on Audis its usually the plugs- coils-icm or battery for that code but vac leak can cause it. Its yet another pinta code to solve.. My A4 did it recently and was the ignition control module but I replaced coils and battery also as I had 90k miles.

 

I personally have never had that code be an injector but the thinking above makes sense.

 

i wouldnt buy all new coils. it's early and my reading com skills may be at ebb tide, but if ONE coil isnt new? then sawp that and make sure all the plugs ( 7/8 bucks each? ) are new,. i realize if you are not actually doing the changing, this is relatively costly due to labor $ but this is what i would suggest you do, make sure ALL the colis.plugs are new. the bosch pugs are pre gapped out of the box.

 

They were all new a few thousand miles ago. So you are suggesting just purchasing an additional new one to swap the suspect coil pack, correct?




How can one test an injector?

 

absolutely if its ONE coli that isn't new like the others. also, check for cracks anywhere. after all its only a plastic housing and thats what fails, is they crack.

i can't help on the 2nd at all. sorry. I've never heard of them clogging and i run some additive cleaning gunk 1 or 2 x a year

 

As rudimentary as it may sound...make sure that each of your spark plugs are properly tightened.

Also, make sure the tappet solenoid brackets aren't cracked...
http://rennlist.com/forums/996-turbo...3-and-6-a.html

(Photo credit to Speedtech John)

 

^thats some fancy ** parts list you got there brother lol..

so do you know what happens when these solenoid brackets crack is it? misfires... thats some complicated stuff, and tough to diagnose i bet.