Just changed from my old Denso Iridiums', to a set of NGK coppers as the old plugs are badly fouled. I've gone with a set of NGK BCPR6EY-11 which I've re-gapped to 0.8mm. Now while the Densos' were in, it had developed a nasty intermittent (intermittent in the sense the severity ranged from mild to unable to accelerate but it was always constant) misfire under boost/high rpm. With the NGKs, the misfire is still there >14 PSI & 4500 RPM, but waaay more linear and controlled and same low level of consistency. It changed significantly, but as I said the misfire is still there. Driving around normally is perfectly fine (probably even better then the Densos' actually), up till those two parameters I listed earlier. EBC is set to 16 PSI on High and 18 PSI for Scramble (which I hardly touch). At idle and free rev'ing, happily rev's its nuts off to any RPM, very responsive and zero misfire. Thoughts? Cheers, MoulaZX
Spark plug choice... thats what I was leaning towards. Just needed some confirmation that indeed the Plugs I chose are sole reason. Those Plugs are recommended for Stock to Mildly Modded TTs. The only thing stock in my engine is the Cams & Cam Gears. I'm thinking the spark is being blown out? This is the first time I've ever run Coppers, always been Platinums before and Iridiums after the rebuild. MoulaZX
i run BKR6es-11 gapped to 0.7 works a treat . arnt the Y shaped plugs the ones with the special V groove?
Is the hole thing breaking down or just a couple of cylinders? You might have a coil pack on the way out.
What PSI though? And yep, it's got that V groove thing. Well, this is where I'm sorta not sure. It 'feels' like just 1 Cylinder is dropping. I guess I could record a clip? MoulaZX
Strange development. Took it out again just now and it only happens 15-20% of the time now when boosting as opposed to the 100% of the time when I first put the plugs in... Wtf?! MoulaZX
If its a sever cut under load, it might be you CAS plug. Give it a wiggle while it's idling, if it stalls, thats your culprit.
It's a minor cut, it still pulls, but you can easily tell the misfire and loss of power however small it is. Engine note changes to that of a very slight resemblance of a WRX engine. I'll double check the CAS plug anyhow. MoulaZX
Yeah...odd. It certainly points to plugs if it improved with the coppers, either that or your getting a weak spark for some reason. For shits and giggles, Run an earthing wire from the negetive terminal to a couple of the upper plenum bolts. Might have a weak ground. CAS is almost always a sever cut as the engine torques over and it moves the loom. This can also be seen with some dodgy coil connections.
so 4k + it splutters and misfires..? i had EXACTLY that a week ago.. drive around normally, no issue, boot it, struggle to accelerate, almost like it was running out of fuel.. changed S1- S2 PTU and hasnt been an issue since
S2 is planned. But it just seems to be a bit of a coincidence that right after I replace 2 Injector connectors, the original hesitation occurs on the Densos, then after I replace the Densos with NGK, my current issues took over. Prior to all that, was running just fine, only 2 days ago, MoulaZX
if you have another PTU or have a s2 ptu get it and put it in... over all runs 1000x better. if its anything like what i said, after 4k splutters, cant accel, almost feels lacking in fuel then change the ptu... took me 20 mins on the side of a car park lol
better... woohoo!! i have power over some one you are so my bitch now... it was actually the CAS.... SYKIE!
:rofl: Not really. I'm just tired of everyone immediately suspecting PTU and giving me crap when they hear that I still have an S1. Then later on fixing the issue... STILL using my S1. Like my own little way to stick it to all you S2 elitist bastards. MoulaZX
Hey Mouly, I think you definitely have a plug issue. That they are coming out black is the first clue. Secondly you are using a JIS standard plug that are physically different to the factory speced ISO standard plug. http://www.aus300zx.com/forum/showthread.php?p=1230120&highlight=spark#post1230120 We have had other members with similar problems that have been resolved by fitting the correct plug. And probably a whole heap with unresolved problems that could benefit from doing so. I would suggest considering OEM recommended plugs setup per Z1Motorsports recommendations, consider for a moment they are probably the most experienced Z32 tune house in the world. http://www.z1motorsports.com/product_info.php?products_id=1621 There is the option to go Iridium and up the heat range to suit boost level per CZP.
