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r34 gt25
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hey guys

i have recently replaced my coils and was driving for bout 2 months and my car started missfiring again

and engine light come on.

i checked the fault and it was fault 21 wen i replaced the coils it missfired every now and then then stoped completely for bout 2 month and now its starting to come back on.

my question is could it be my plugs or something else. i want to get it running properly so i can sell it as i need a bigger car cos i have a two week old little girl now and the 34 is to small lol

any help is much appreciated

thanks

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when was the last time you changed the plugs? if it's been a while I'd get those changed first as it's a cheap and quick fix. If it's misfiring on idle / low rpm, try a higher gap ... my 34 would constantly misfire on the copper NGK's on gaps smaller than 1mm (but just on idle and upto 3000rpm)

Get the NGK coppers ..heatrange 7 and try a .9 or 1mm gap, if that doesn't fix it search for "misfire" and see what else it could be. Chances are it's just the spark plugs.

If you're not mechanically inclined, take it to Unigroup in Girrwaeen they'll take care of it and won't charge crazy labour rates like some other shops.

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when was the last time you changed the plugs? if it's been a while I'd get those changed first as it's a cheap and quick fix. If it's misfiring on idle / low rpm, try a higher gap ... my 34 would constantly misfire on the copper NGK's on gaps smaller than 1mm (but just on idle and upto 3000rpm)

Get the NGK coppers ..heatrange 7 and try a .9 or 1mm gap, if that doesn't fix it search for "misfire" and see what else it could be. Chances are it's just the spark plugs.

If you're not mechanically inclined, take it to Unigroup in Girrwaeen they'll take care of it and won't charge crazy labour rates like some other shops.

thanks mate ill give it a go and what size gap do u run on your 34 and is yours turboed or na

mine is na

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I run 1mm and its a turbo .. not really sure what the right plugs are for an NA to be honest. But you shouldn't need a lower gap if there's no boost to blow out the spark especially if you've got new coils

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when was the last time you changed the plugs? if it's been a while I'd get those changed first as it's a cheap and quick fix. If it's misfiring on idle / low rpm, try a higher gap ... my 34 would constantly misfire on the copper NGK's on gaps smaller than 1mm (but just on idle and upto 3000rpm)

Get the NGK coppers ..heatrange 7 and try a .9 or 1mm gap, if that doesn't fix it search for "misfire" and see what else it could be. Chances are it's just the spark plugs.

If you're not mechanically inclined, take it to Unigroup in Girrwaeen they'll take care of it and won't charge crazy labour rates like some other shops.

You wouldn't have the part No for those plugs by any chance ?

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I cant see faulty plugs throwing a code 21. Check your loom and plugs to the coilpacks. Make sure the metal connectors inside them are tight. Could it be the coil ignitor also?

On the 34 the coils igniter is built into the coil also does anyone know what coils mainly go first and also how much would the plugs cost because most of my money goes towards my house and baby girl now.

thanks for any help you guys can give me

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BCPR7ES or BKR7ES

add -11 at the end if you want the ones gapped to 1.1mm from factory.

Edit: kudos has them http://www.kudosmotorsports.com/catalog/ngkntk-m-5.html ..but most import tuners would have them in stock too.

Thanks for that, I did a quick check of NGKs site so it's interesting to note that both the Iridium (BKR6EIX-11) and the Platinum (PFR6G-11) for A 98 R34GT-t have the 1.1 gap specified.

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the iridiums and platinums are a waste of money. they don't really last any longer but cost a heap more. you should be able to get the plugs at any store that sells plugs (supercheap, repco, autobarn, etc) as they aren't just used by imports. 1.1mm gap is good if the coils are nice and strong. if they were old then i would say to drop the gap, but since you say they are only 2 months old run the bigger gap in the copper plugs. unless the coils you put in were second hand then it might be a coil issue and not a plug issue (but at less than $30 for a new set of plugs it wouldn't hurt to do them anyway).

i also discovered a few weeks back that the BCPR plugs are a taller plug than the BKR plugs (by about 4mm i think it was), so they make better contact with the coils.

i ran BCPR6ES in my 33 gts-t and it was fine gapped at 0.8mm. no missfire at all and i was running the stock coils and 14psi.

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when was the last time you changed the plugs? if it's been a while I'd get those changed first as it's a cheap and quick fix. If it's misfiring on idle / low rpm, try a higher gap ... my 34 would constantly misfire on the copper NGK's on gaps smaller than 1mm (but just on idle and upto 3000rpm)

Get the NGK coppers ..heatrange 7 and try a .9 or 1mm gap, if that doesn't fix it search for "misfire" and see what else it could be. Chances are it's just the spark plugs.

If you're not mechanically inclined, take it to Unigroup in Girrwaeen they'll take care of it and won't charge crazy labour rates like some other shops.

my car is running fine now again and i know my car has triple platinums at the moment so are the copper ngks just as good

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yeah the copper NGKs are just as good but cheaper but may not last as long as platinums ... So what did you do/change so that it works again?

At the moment i havent done or changed anything ill put the NGKs in when i get paid on thursday

also i found when i put the car into tiptronic thats when the problem started so does anyone know

how to check the faults on the gearbox or will they come up when i check the warning light codes

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Does it come good when you give it a gut full?

Change the plugs....

Cheers..

At the moment i havent done or changed anything ill put the NGKs in when i get paid on thursday

also i found when i put the car into tiptronic thats when the problem started so does anyone know

how to check the faults on the gearbox or will they come up when i check the warning light codes

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i have recently replaced my coils and was driving for bout 2 months and my car started missfiring again

and engine light come on.

i checked the fault and it was fault 21 wen i replaced the coils it missfired every now and then then stoped completely for bout 2 month and now its starting to come back on.

In your last post, you mentioned that the misfiring goes away when the car cools back down.

So I assume that the misfiring got worse when the car is warmed up...

Q. Is the car running rich? The plugs will tell you if you are.

Q. The coils you obtained; were they new or 2nds (since I know you're on a tight budget)?

Coils tend to play up when the car is warmed up completely and the car is running rich. Second-hand coils more so...

When you take out the plugs, check if you're running rich & take the coilpacks out again and see if there are any scorch marks (particularly if you got 2nds). Check the Sticky on Misfiring if they're suspect and tape them up with high quality electrical tape.

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In your last post, you mentioned that the misfiring goes away when the car cools back down.

So I assume that the misfiring got worse when the car is warmed up...

Q. Is the car running rich? The plugs will tell you if you are.

Q. The coils you obtained; were they new or 2nds (since I know you're on a tight budget)?

Coils tend to play up when the car is warmed up completely and the car is running rich. Second-hand coils more so...

When you take out the plugs, check if you're running rich & take the coilpacks out again and see if there are any scorch marks (particularly if you got 2nds). Check the Sticky on Misfiring if they're suspect and tape them up with high quality electrical tape.

yeah im on a really tight budget with a home loan as well i got a set of second hand coils off a guy on here said they were fine

the car doesnt get worse when it warms up just stays the same if i knew someone in west sydney that had the software to turn off each cylinder i could find the problem coil and replace it with one of my ones maybe

what does taping them up do. thanks for all the help guys.

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Under "Important Topics" above your thread, there's another thread called "Missfire Boost@4500-5500 RPM which tells you why taping up the coilpacks can lengthen the life of them.

I have a second-hand set which may be still suitable for an R34 NA that are 'taped & siliconed'. You are welcome to try them out to see the difference - but I'll need to check the specs of them when I get home from clinic (ie 10.30pm). They're off someone else's R34 GT-R and I keep them as spares.

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