berkel

iTrader: (5)

Hi all,

Well, I've battled misfire or boost cut near the tq peak in the past, but thought I had it squared away with NGK copper plugs gapped to .26 or so.

Lately, misfire around 4500 rpm was getting worse and worse. I had ordered NGK BPR8es to try (I was running the BPR7es). I installed 3, then realized that the 4th was a BR8Es. The "P" means protruding or something to that effect, and the BR8es electrode didn't nearly stick out as much. I had bought 8 plugs, so with 5 BR8ES's, I had to try that route (and remove the 3 I had already torqued down )

Anyway, the next day, car idled and drove great at light throttle, but WOT anywhere near tq peak caused misfire. What a pita.

I ordered more BPR7es and BPR8es, but I found some BPR6es locally. If this doesn't fix the misfire, any other ideas? I have magnecor plug wires, if one were bad could it cause misfire only at tq peak like that?

What about the coils? I had a coil go bad in my A4 (what a surprise), and it caused a cel and that cylinder didn't run at all.

I hope the plugs help, if not, I'm going to bag my plan to get cams in April for my bday until everything is sorted out.

<edit>
BTW, forgot to mention I even turned boost way down, but even at 15 psi it stumbles and misfires near the tq peak... Also, no cel, flashing or otherwise...
</edit>

TIA,

FB

EVOONYOASS

iTrader: (2)

If your coils were bad you would know it, no spark. Could be one of the wires, you could always test them to see if they are still good. I would stick with the 7's on your plugs and I would also keep the boost for what ever you tuned the S-AFC at. You don't need to run rich right now trying to figure out a misfire problem.

1. Double check the coils
2. Check the wires(test them, not visually)
3. Check for boost leak(pressurize system, spray soapy water on all piping)
4. Check and see if your gauge is reading the same boost you tuned it at
5. Bad gas?

What if anything have you changed or done different? When did the problem start?

berkel

iTrader: (5)

Thanks for the feedback.

Driving today with the BPR6ES, car is much, much better.

I think the non-protruding NGKs (BR8ES), esp in heat range 8 don't work in my car...

I turned up the boost slightly, to 18 psi or so, and I get intermittent slight hesitation/stutter around tq peak... I may swap my wires for the stockers and see if it helps.

Car was running great prior to the BPR7ES misfiring. I was really hoping this ongoing problem was fixed. My guess is the plugs are just fouling and need to be replaced more often. Maybe the wires are screwing me up too.

We'll see what happens with the stock wires. I'm glad it's probably not the coils, there probably fairly expensive..

Take care,

FB

smackdaddy

iTrader: (2)

berkel,
Funny you posted this as I am having the same issue at this very moment myself. Just swapped from stock wires to magnecors, and that did not help me. Replaced NGK BPR7ES that had only 2000 miles on them and regapped to .028 and that didn't help either. My coil packs look good physically, not melted like some have eluded to in other posts. I'm also going to pull the coil packs and visually inspect the boots on the bottom of the coil packs for any small pinholes that the spark could be arcing through the boot before getting to the plug. I've been told that it could leave a small hole maybe with some white markings around it. Right now, I'm wondering if a coil pack can be weak instead of just failing entirely? Also going to drop the gap down to .025 and see if it changes anything. I Hope this gives you something more to think about as well.

berkel

iTrader: (5)

Hi,

Yeah, I love this car, but this is the ongoing pita I've dealt with. One of the best parts of the rpm range, and I always have to think twice about going wot through there, fearing it'll stutter. I've been really happy over the past few months when it wasn't happening, so I hope I can get it all straigtened out.

The BPR6ES plugs definitely helped, car was running dreadfully with the BR8es... The fitment on the magnecors isn't ideal, although I've had them for over a year now. I'll just try the stock wires to take it out of the eqn.

Not sure on a slowly failing coil pack. My A4 coil pack failed all at once and threw a cel. I could barely limp the car home, it was ugly. You could smell all the unburnt fuel and the cat was BRIGHT red...

Good luck,

FB

GBEvo

iTrader: (4)

I have the same problem. I swithched wires to the Magnecore 8.5 and it didn't help. I pulled the plugs and they looked fine. Regapped them to .026 and I still get the Fuel/boost cut. It happened only once in 3rd but quite frequently in 4th and 5th between 4k and 5k rpms. I also tried turning the boost down with no luck. It is a pita. Mine started as soon as I put the intake on. I was told that I needed a flash. Let me know if any of you find a solution that works. If I can't find a fix, I'll try a flash sometime this spring/summer. Thanks!

smackdaddy

iTrader: (2)

well, mine seems to happen most in 1st-3rd gears. I've dropped my boost down to 16psi and it still happens although not quite as badly.

KillaSweep

iTrader: (1)

Well although you guys might probably laugh.....check your fuel pump....2 stock fuel pumps have failed on me and the dealership has replaced them both times. When it failed the exact same symptoms that you are describing took place. As soon as the heavy boost came in this sputtering/misfire noise started and got worse and worse the more you stayed in it.

Note: the dealership kept guessing at what was wrong...new bov, new coil pack, new plugs, vacuum hoses, and even tried blaming my boost gauge..haha stupid phuckers.

P.S. I'd almost put money on it that the fuel pump or fuel sock assembly is what is causing your problem. They don't throw misfire codes either....and you don't have to have very high boost for it to occur, but if you aren't getting enough fuel when the turbo needs the most gas it will cause a misfire. Goodluck

smackdaddy

iTrader: (2)

Ill through that out the window, on a walbro 255 with 780cc injectors. I can drive through the misssing and after the torque peak I can continue to accelerate up into higher rpms with out a problem. Doesn't make sense to me at all. you'd think if it was going to miss, that 21psi at 5-6k rpm would produce the problem. no such luck, only happens for me around 2500-4000k rpm. How bout you berkel?

berkel

iTrader: (5)

Hi guys,

I also have a Walbro pump. Also, I can also accelerate in the upper rpms, like after 5k without the stutter. I would also think that a failing fuel pump would be hurting in the upper rpm, right? I hope that's not the problem anyway. Also, my problem got much better with diff plugs, so I think I'm on the right track.

Since a third poster mentioned magnecor wires, that does seem suspicous, eh? I'm gonna swap wires as soon as my daugter goes to bed.

Regarding the intake, I do think you need a flash with an open element intake since it can cause funky maf readings. I have stock airbox with K&N drop-in.

Thanks for the posts guys, wish me luck with the wires, although I'll be bummed if the fairly expensive magnecors are no good.

FB

EVOONYOASS

iTrader: (2)

Sounds like a tuning issue maybe with the S-AFC at that certain rpm range. Who tuned it and was it on the dyno? Did they use a wideband O2 or a sniffer?

If your S-AFC has too big of a gap in between rpm ranges and you can't fine tune that area, that might be what is causing your fuel cut. Just a guess.

berkel

iTrader: (5)

Hi, in my case the SAFC isn't really tuned at all. When it first started happening last year, leaning out slightly in those rpm range (4-5k rpm) seemed to help. Doesn't seem to help as much now.

I just swapped the stock plug wires back on. Those thing are thin as hell, but they seem to have a snugger fit on the coils and they seem to seal at the two cylinders better. I'll let you guys know after my drive to daycare and work tomorrow. =)

Car felt pretty good on the way home from work, but still the occasional hesitation between 4-5K, usually 3rd and 4th gear for me.

Take care,

FB

Ev0ikon

iTrader: (18)

replaced my plugwires with from Magnecore 8.5mm and P0300 never came back. It's been about 5-7K miles since.

EVOONYOASS

iTrader: (2)

Sorry to tell you but that sounds like your problem right there. You can't just hook up a S-AFC and make adjustments without knowing if the adjustments are correct. I don't know what size injectors you are using but making adjustments on the S-AFC without seeing air/fuel ratio's is going to hurt your engine performance. If you copied #'s off the forum and put them in your S-AFC your liable to do more damage than good. All cars are different and particular settings for one car will be different for another. I suggest you get it to a dyno as soon as possible and have them tune your car properly. If you had told me this in the beginning I could have told you your problem sooner. Hope it works out for you bro. Sorry you had to learn the hard way and I hope you didn't screw up your engine. Good luck.

11secEVO7

iTrader: (37)

if it was the coils you would get an idle problem as well....