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Discussion Starter #1
I had missfiring above 5k rpm, but after a clean of plugs and refurb of coilpacks, i had the motor running completly smooth, just a few days from then i fitted the japspeed twin silencer system, de-cat and downpipe/elbow all in one, but its missing again at full throtle above 5k rpm. time for bigger AFM, intercooler, Apexi controller and stuff ? Or is there a simple reason for this missfire with the new exhaust ? Also anyone know how to safely extinguish the exhaust overheat light now theres no Cat, if its that sensor ?? Or is it the one on the elbow that makes the red light stay on ?

many thanks peeps !
 

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I recon that you just have a coil-pack breaking down and as for the sensor, if its the one off the de-cat then just chop it off if there is not a place to mount in in the de-cat pipe. I am sure if I am wrong someone on here will put it right. Good luck though
 

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i had a similar problem, a slight flufyness above 5,500 rpm, if i took the plugs out cleaned and refitted them and the coil packs it runs fine for a couple of days, i did this twice and could'nt see anything wrong and it still went fluffy again so i fitted a new set of ngk iridium 6's and it has made it pull clean and strong right upto 7,500 now, throw the plugs away and fit some new ones!!
 

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Discussion Starter #4
mmmmmmmmmmm, all makes sense. They are iridiums in the engine, but 7's i think. Might just pop a new set in anyway as the ones in there are a year old now. The warning light, thats baffled me, there is the hole to screw the sensor in on the japspeed de-cat pipe, but it doesnt get shot of the light, tried pulling it out, still stays on.

I think, HAH, new plugs, splitfire coilpacks, bigger intercooler, Z32 afm, and apexi controller for fuel and air and then sell the car as i need something to carry a dog in soon.

If anyone has any of the above mentioned, let me know. And thanks for your advise so far, much appreciated !
 

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I had missfiring above 5k rpm, but after a clean of plugs and refurb of coilpacks, i had the motor running completly smooth, just a few days from then i fitted the japspeed twin silencer system, de-cat and downpipe/elbow all in one, but its missing again at full throtle above 5k rpm. time for bigger AFM, intercooler, Apexi controller and stuff ? Or is there a simple reason for this missfire with the new exhaust ? Also anyone know how to safely extinguish the exhaust overheat light now theres no Cat, if its that sensor ?? Or is it the one on the elbow that makes the red light stay on ?

many thanks peeps !
fitting a elbow would have increased your boost,id say your blowing out your spark, try droping your plug gap
 

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Fitting complete exhaust system lets your turbo breath better and lifted up you boost slightly. More boost=more air! More air=more fuel! Your overfueling now if you don´t have SAFC or similar. That´s the reason for your misfiring. Try gapping plugs to 0.8mm first and cleaning packs. If not try new plugs-buy pregapped ones! If still s**t try coilpacks-I prefer Splitfire. Of course Apexi SAFC or ECU does help you a lot, cause you can control AFR and avoid overfueling!

Hope this helps! :cheers:
 

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Plug gap first mate, your exhaust is more free flowing better boost build up. LIke slingo says, drop teh plug gap. If it aint that then its i definitely your coilpacks....
 

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Discussion Starter #9
Grand, all makes sense, thanks for the tips. Ill have the plugs out tommorow before i make the journey from lincolnshire back to scotland. I want the splitfire coilpacks and a SAFC as soon as i can, just need to locate them for a good price :)

And on another note: Flames, should i expecting any or not ? Cause i read some say with elbow as well you should, others say no....
 

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depends on the fueling.... if your overfueling then probably a few flames but if the safc is mapped properly then you might have the odd few when booting it....
 

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Discussion Starter #11
Put a post up on wanted parts for a SAFC to sort me missfire, or at least aid in resolving the problem, I hear Apexi is a good one to go for ?? Also splitfire coilpacks, then i should be on the way to getting the problem sorted.

Thanks again !
 

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Discussion Starter #12
Big thanks to all for the advise, esspecialy Blitzer for the thought on gapping the plugs, I did that just today, got above the 5 k rpm mark, and it kept going trouble free ! So im well happy, feels like i got the BHP that i should have with the mods so far. I feel it running sightly flat ( still pulls no problem 5-7k rpm ) So i think an AFC type thing should help, boost the fuel rate a bit, but get new plugs anyway and the coilpacks.
 

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Im planning on getting a 3" turbo back exhaust this coming weekend...Im just concerned about this running flat thing when getting a new exhaust...Is this a common problem or issue??? Because at the moment i have NGK Irridium plugs...
 

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Discussion Starter #16
Well, talking to me dad who used to tinker with old baford begal vans and the like, reckoned he same as me that regapping the plugs by Blitzers recomendation makes sense, so i regapped them today, tried to find some straight road to get up through the gears, missfiring gone ! - But i can feel a tiny tiny flat spot, or more like a tiny drop in power above 5k rpm to the redline, so im guessing whatever that may be ( although in no way obtrusive ) a controller for the air and fuel flow will aid in that. Then splitfire coilpacks and new properly gapped plugs, bigger intercooler....and that will do for the engine for me for now i think ??...But im happy to feel the grunt back again ! I want to get some videos done when i get back home as i promised Japspeed i would as a happy customer. Again, thanks for all the help ! Where would i be without this forum !??
 

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Discussion Starter #17 (Edited)
I think for me because its the entire 3" system turbo/elbow all in one, de-cat and twin silencer the rest of the way, thats why i feel, or at least think i feel a minute tiny little drop of ..IE. 100% most of the way to 95% at the top, but seeing as my plugs are a good year old now and im running other minor mods - might be time for an increase/adjustment to fuel and air flow.

I think you will be fine with those plugs myself. If you get any missfire like i did after fitting your system, regap them and you should be fine im sure.

PS)as by an old thread, but sure is good, if you get that hunting problem when the idle sped drops with aircon on, take that aux idle controller do dar off the back of the intake, near the clutch and brake fluid resevior and clean it out - excellent results for me - problem solved.
 

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This seems such a good thread - so rather than start a new thread a month later ...

I wanted to ask a few questions - because I seem to have a similar issue ...

I bought my R33 GTS25T totally stock ... but added HKS actuator (as the standard was boosting only at 0.5bar) and an HKS panel a/Filter ... by the way, the boost was set at 0.7bar and heat range 8 Iridium NGK plugs were used.

I noticed that during colder weather there was a slight mis-fire at between 5,500 Rpm and 6,000 Rpm ... so I VERY CAREFULLY re-gapped the plugs to 0.8 and the problem was cured ... although I did still notice that she still perhaps didn't quite pull as hard in this little 'band' of the rev range, but this was hardly noticeable - so I never really paid it any more mind

I then fitted recently an RSR-Invidia straight thru Cat-Back 3" Exhaust System ... and once again the symptoms have returned slightly ... the mis-fire during colder spells (mainly at night) is slightly there and in the day time the hesitancy is there in the 5,500 to 6,000 rev range .... with what seems a bit like a 'surge' in power between 6,000 right up to the 7,000 red line ... it's therefore a bit like driving an S2000 cos you really notice the increase in pick-up right at the high end of the rev range, near the red line Hahahah!!

But, jokes apart, I think it isn't the plugs as they are '8' heat range so they are nice and 'cold' and the coil packs were all cleaned and refitted ... could it be that there is a little too much boost which is making the car over fuel at this point in the rev-range??

I have a buddy who is a bit of an ECU expert and ( I ashamedly know very little about this stuff or anything really to do with mechanics) he says that it could be a 'blip' in the "Throttle Switch" mechanism ... and I may therefore need to replace that ... rather than getting an after-market SAFC to regulate the fuel flow ...

I, myself am not sure .... I also wondered if any of you in your better experience and knowledge than me would honestly think that the mods I had made to an otherwise 'stock' car would necessarily warrant having an uprated SAFC fitted???

Please can you help? :confused:
 
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