I had no luck with these plugs. Ran a lot worse than the platinum Densos. Just my experience.

Andreas

 

Ok since you are catless disregard the o2s for now ,ots not that. Check all the vacuum lines again but since it is intermittent and on one bank it sounds like something electrical. Double check cam sensor for that bank . The ground strap is on chassis above passenger turbo . It grounds the engine to chassis.

 

did you measure the plug gap? mine are gap at .024 before 0.28 and i had a lot of misfire

 

That's the first thing you should have done.

 

For future reference; the problem was fixed by changing the bank 2 o2 sensor (the sensor responsible for cylinder 4, 5, and 6). Since the tune is now mafless, the o2 sensor is relied upon more than others.

Thanks for everyones help!

 

Glad to see problem solved. By 'changing' you mean replacing the O2 sensor, right? (I've seen people swap O2s to see if faults follow the part to the other side)

Henry

 

Wow i forgot about the 02 sensor this is great info. Im glad you fixed it but would like to know how did you guys find the issue????

 

Luckily my buddy had two spare o2 sensors... He had only used them a few hundred miles. I figured I'd plug a new one in and try it out. Vwala.. Problem gone.

It goes to show how important your o2 sensors are for driveability. Mine are most likely 5+ years old before I switched to the new ones. It took a mafless tune to figure out they were (ok only one was) bad. The car is smoother than it has ever been. Something to look into for cars that arn't running perfectly.

 

OP. have you put some miles in with the new O2 sensors ? I had that happen last year and replaced with brand new sensors, had problem come back 6-700 miles later, swapped them and problem would come up intermittently, then I would get left side O2 codes. Turns out it was a crack in the weld of the cats that were only noticable once warmed.

 

Its funny you say that. I just tested the car again today (which before I had just driven around a little) it missfires badly once I hit 1.2bar (1.4 bar being my peak). This time the missfires are coming from the other bank. Im going to switch my o2 on the other side (bank 1) with a newer one now. If that doesn't work, ill look for some cracks.

 

Update: I changed my plugs, and gapped them to 0.025" (0.63mm). This worked! The car no longer missfires at wot. I assume the bad o2 sensor caused the plugs to foul from running rich.

 

That's great! So you didn't end up replacing O2's on Bank 1? Do you know if your bank 1 and bank 2 AFRs are pretty equal?

 

I haven't done much dataloging since the fix (it was today and I haven't driven much since). I did replace the bank 1 o2 the previous day and it had no effect.

Hopefully my afr's are the same now!!

 

Which plugs did you end up going with?

 

when your car misfires at WOT. does it make a muffled popcorn popping sound?
I have been fighting a problem that I think is missfiring not Knock.
I have heard knock and it was much louder of a sound. my durametric does not show misfiring counts though.
I changed my spark plugs but did not regap them. and the problem lessoned some.

However this misfiring is not something I Feel. I really just hear it and it's only in above 1.0 bar mostly if the engine is colder and the waterinjection is on.

do you hear your misfire or just feel it?