Jump to content
SAU Community

Recommended Posts

i was gettin a misfire on high boost before, so i put in new plugs gapped to 0.76mm (damn non-metric feeler guages:D )

anyway, now it pulls hard all the way to redline on 1bar boost, but it seems to misfire at idle?! (sounds like ive got cams!) is this because im now running too small a gap? or is this what you sacrifice in order to get a reliable spark under high boost?

thanks

adam

Link to comment
https://www.sau.com.au/forums/topic/6160-plug-gapping-and-misfiring/
Share on other sites

Could be the smaller gap and worse still if you have installed a colder heat range of plug.

The smaller gap/colder plug provides better combustion for top end (as per the reason you did it) but, provides poor combustion at idle. The plugs will have less life in them as well.

Best thing to do is practise changing plugs, so you can change to a colder set for race use and leave a nice warm setting for the street. Poor combustion also shortens the life of the engine BTW.

but theres only poor combustion @ idle so should be sweet:P

i dont fancy changing plugs THAT often, took me long enoug thanks to nissan's coil packs :) the plug is 1 heat range colder, so thats gunah add to it as well.

i guess im sacrificing the bottom end for top end, as it seems to go with turbo cars when they make big power.

The plugs foul at idle, and get cleaned up when you floor it.

They just won't last as long as your old ones. Why not run the gap at 0.9 or so, with a colder range plug I'm sure you won't be down any power and it will give back the idle perhaps.

0.9 on a colder plug should be fine.

Nope! I've tried numerous combinations with heat range and gap, and what I'd recomend for street use is a heat rating of 6, and a gap smaller than 0.8mm. If you have an aftermarket ECU, or a SAFC, then this recomendation doesn't really apply to you...

With stock ECU, b/c the mixtures can get really rich, you need a warmer plug that can burn some of the carbon deposits off the plug. The colder plug will not last long, as it will get fouled very quickly (a couple of weeks), and will need to be pulled out to be cleaned. A warmer plug will go a lot longer before it needs a clean.

As for gap, I've tried

0.9 with a colder (7) plug, 0.8 and 0.7 as well. I found the smaller gap to be the best....

But like I initially said, a warmer plug and smaller gap is best for street use..

I'd say NGK BCPR6E (NO S). This has a heat rating of 6, and the v groove. Gap this anywhere between 0.65 and 0.75, and your Line will run much better (remember, only if you nave stock ECU meaning rich mixtures). At this configuration the 5000rpm misfire on the R33 happens much less!

I only see it when I have been driving the car for more than 30 mins... weird!

Zahos

Originally posted by Zahos

But like I initially said, a warmer plug and smaller gap is best for street use..

I'd say NGK BCPR6E (NO S). This has a heat rating of 6, and the v groove. Gap this anywhere between 0.65 and 0.75, and your Line will run much better (remember, only if you nave stock ECU meaning rich mixtures).Zahos

Zahos ... does this apply to R32s as well??

OK then, well I guess the same theory applies to R32's as well. But no matter what, if u have stock management, and higher boost, you will see this problem. What I suggested merely deminishes the magnitude of the problem, and will prolong it from creeping up. I have had my plugs in for 2 months now, and I dont see the problem very often (running 0.7 bar ~10psi).

Originally posted by Zahos

Nope! I've tried numerous combinations with heat range and gap, and what I'd recomend for street use is a heat rating of 6, and a gap smaller than 0.8mm. If you have an aftermarket ECU, or a SAFC, then this recomendation doesn't really apply to you...

As for gap, I've tried

0.9 with a colder (7) plug, 0.8 and 0.7 as well. I found the smaller gap to be the best....

But like I initially said, a warmer plug and smaller gap is best for street use..

I'd say NGK BCPR6E (NO S). This has a heat rating of 6, and the v groove. Gap this anywhere between 0.65 and 0.75, and your Line will run much better (remember, only if you nave stock ECU meaning rich mixtures). At this configuration the 5000rpm misfire on the R33 happens much less!

I only see it when I have been driving the car for more than 30 mins... weird!

Zahos

Adam's got an HKS AFC thingo.

Like you I run the stock rated 'warm' plug. Regardless of gap they (warm plugs) will have a nicely cooked electrode in no time with a setup like Adams with revs and tO4 style boost.

the problem doesnt seem to be as bad anymore actually. im not sure why...

even if it didnt rectify itself i was happy to run a 0.75mm plug gap as it pulls very nicely through top end

jimi if ur running the VG30 at that sorta boost (which u should :D) then run the same plugs as me. i think theyre BKPR6ES or something

what gap do u guys think I should run:

I have -

full exhaust (dump, front and rear)

10 - 11psi boost

pod

cold air intake

Also, how long does it take to remove all of the stuff under the plastic panel on the engine head to get to the plugs? is it hard (i got to it and then stopped)?

thanks

Try 0.7 or even 0.65+

A good spark plug (copper) is NGK BCPR6E

Platimuns r good, but not worth the money, as the only benefit they have is a longer life span. I dont plan to leave plugs in there that long anyhow, as they foul easy when running rich....

I have the same problem with my r32

Running 19 psi through a hks gt2535 and a rechipped computer it misses at about 5000 rpm.

Have tried lots of different things to fix it with no luck yet.

Iam now running a gap of .65 and when i did this it developed a miss at idle (like adam32) . This does not worry me as all i want is for it to rev cleanly to redline.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • The German place in Cabramatta was rock solid, fresh pretzel cooked to order back then. Then it went all quiet, after all the poker machines were removed, then I believe it closed for good. I did drive past the other week and noticed outdoor lighting a big screen, but no idea what is there now.  
    • Yeah I suspect even if you hold airmass per cycle/cylinder constant if you get too far away from stock you're still going to have problems running the factory tune within the bounds of the factory load scale. Cams, different displacement/rod ratio, etc. I'm just lucky that the GTIII-SS with wastegate boost + CA compliance cats is pretty much equivalent to stock turbos. When I have actual space I can finally get it tuned and modify the fuel system for flex fuel to 100% handle any detonation concerns when cranking the boost to whatever those dinky turbos can put out.
    • I would say no, why, because my daughter, who also lives in Goulburn, hasn't recommended us going there Pity, as we miss all the German joints around in Sydney, actually, the restaurants are the only thing I really miss about Sydney, and a special mention to Ishibanboshi at Bondi Junction, their Kara-age Don is heart cloggingly deliciousness (always added a special boiled egg...or 2) 😋 
    • Does that German restaurant still exist in the old place out the NW end of Goulburn? When I say "out the NW end of"...I am really being vague. It was 1997 when I was last there, and the only point of reference I can recall is that it was on the opposite side of the main drag from the big merino. And when I say "opposite side of the main drag", I don't mean "on the main drag". It was either a couple of streets back from there, or might have even been out in the sticks a bit further. Was an old farm building or mill or somesuch. And when I say "the big merino" I might actually be thinking of a completely different part of town, because I just looked on maps and the big bugger is not where I remembered him to be! The food was good, consisting largely of various German mystery-meat sausage/loaf things and kartofflen.
    • So while the second sentence is completely correct and the whole point of the conversation, the first sentence bears consideration. If this bloke is just hoping to throw big turbos on and drive it around, because there are no helpful facilities at all in his tropical paradise** then he likely has zero chance of even knowing what the TP is on the last column in the stock maps, let alone know whether the ECU is operating anywhere near it or past it. So the point is very very moot. And, per what I said before, at stock boost on those turbos, you may well be off the end of the map. **I'm just back from Vanuatu, so I know exactly what small Pacific nations can be like wrt paradise without requisite facilities. But it's not even that simple. I put a high flow on my car and had to drive it around without a proper tune because of the lack of opportunity*** to put the bigger AFM and injectors into it to allow it to be tuned. I had to turn the boost down to less than I had before, and back off the boost controller's ramp, because it was exploring parts of the map that it didn't drive in before, and really couldn't access for tuning on the dyno either, and so was pinging. It was still well within the last column, because when I first**** set up the Nistune on the Neo I rescaled all axes of the maps to give some more space to explore. ***Family dyno was broken ****This was 13 years ago, and the TIM thing wasn't a thing then and so TP would definitely grow when pushing past the stock tune's limits.
×
×
  • Create New...