Bad Miss In High Rpm

[yellow34gtt]

Hi to all,

i need some advice on a problem which by other post sounds quite common in 34's

let me first infom you what i have had done recently to my 34gtt $ 6500.00 later i have my turbo hiflowed with trust internals from GCG, 550 cc injectors, apexi power fc computer,full hks super drager exaust,front mount, dump pipe, runnin 16 psi,walbro 255 lt pump, only just put in thinking this may fix my problem.

ok here is my problem when at hi rpm say 3500 upwards and anythin above 10 psi i get pap pap pap sound like a boost cut sound some times it runs good and some times it runs bad, it was tuned in brisbane and all went fine untill i return home I'm about 900 mtrs above sea level a bit colder temp as per say.

if anybody can help me with a solution or advice my mechainc says it now could be coil packs and recomends split fire items at a Cool $ 1000.00

any help would be great thanks heaps ......

[danielson]

dirty afm maybe??

[yellow34gtt]

dirty afm maybe??

thanks it's a one more thing i can check , it is one of those things that is driving me mad..

could it be spark related....

[R33-Lovr]

do you have a blow off, that might be it, the spring could be too lose or too tight,

i heard the stock coils are good enough you can take them out check if they r burned from the side if so that might be the problem. but better off take it through a dyno run and hopefully that will pick up the problem.

then again maybe your not leting enough fuel in for higher boost

[Tosh]

I agree with your mechanic... the amount of R34 GTT's we've had in the shop with buggered Coils after being boosted is astounding. I also agree with his reccomendation for Splitfires

[yellow34gtt]

do you have a blow off, that might be it, the spring could be too lose or too tight,

i heard the stock coils are good enough you can take them out check if they r burned from the side if so that might be the problem. but better off take it through a dyno run and hopefully that will pick up the problem.

then again maybe your not leting enough fuel in for higher boost

o yes sorry i did not mention yes i have a bov and will play around with it tomorrow and check the packs too.

the funny thing is when i take my car down the coast it runs fine, i did that exact thing to put it on the dyno and it did not play up a bit even the stock pump was good for it ,it made 195 kw at the wheels at 14 psi stupid aint'it ......

[yellow34gtt]

I agree with your mechanic... the amount of R34 GTT's we've had in the shop with buggered Coils after being boosted is astounding. I also agree with his reccomendation for Splitfires

thanks for the info looks like i may have ta fork out some $$$ and put some new coli packs ..

but i cannot work out why it runs better at the coast and only some times it acts up, it's more freqent now it is getting colder....

[Modena]

thanks for the info looks like i may have ta fork out some $$$ and put some new coli packs ..

but i cannot work out why it runs better at the coast and only some times it acts up, it's more freqent now it is getting colder....

I have the same spluttering problem in my R33... on the weekend I will inspect the coil packs and clean them from the inside... also check out the AFM...

Does ur car stall after this problem too?

Is it just me or is there way too many people cars with these problems????

[ZERO]

first of all dont pay for splitfires for $1000. buy them fron nungun for a cool $564 delievered to you door

i got mine 2 weeks ago... same thing is currently happening to me and i have stock engine aprat from boost to 10psi, front mount, full exhaust,filter and BOV,

when i hit boost around 4-5 to goes pap pap pap lags and then hit again...

but its not a smooth and quick delivery like most turbo cars should go...

but when i leave the car on 7psi its all fine no pap pap lagg...

i am also trying to find out the problem what i was thinking was maybe it was boost cut on the R34's or maybe my VTT is f**ked cause of the bad coils from before.

i have a apexi computer i want to put in and find out if it's the problem but not enough funds at the moment. BUT you have an apexi computer so i dont think there should be any fuel or boost cut. computer should have difused it...

Edited May 18, 2006 by ZERO

[yellow34gtt]

first of all dont pay for splitfires for $1000. buy them fron nungun for a cool $564 delievered to you door

i got mine 2 weeks ago... same thing is currently happening to me and i have stock engine aprat from boost to 10psi, front mount, full exhaust,filter and BOV,

when i hit boost around 4-5 to goes pap pap pap lags and then hit again...

but its not a smooth and quick delivery like most turbo cars should go...

but when i leave the car on 7psi its all fine no pap pap lagg...

i am also trying to find out the problem what i was thinking was maybe it was boost cut on the R34's or maybe my VTT is f**ked cause of the bad coils from before.

i have a apexi computer i want to put in and find out if it's the problem but not enough funds at the moment. BUT you have an apexi computer so i dont think there should be any fuel or boost cut. computer should have difused it...

thanks ZERO for the tips,

1st is this nungun an overseas mob or can you contact them in aus i would prefer a local person for these kind of buys

so you put your new coil packs in and it did the same thing is that what you are describing ....

mate your car has definatley a boost cut at 10 psi with a standard computer i found that out straight away when i got my car and have you changed the spark plugs that could be one of your problems and also your fuel pump for good pressure up high, test it at where you drive it most i have found it changes if you live where it is colder or if you live up from the coast ..

[12DFY]

Hey guys with all the same problem, usually the problem you describe is related to incorrect spark plug gap. If you run above 10 PSI you should consider dropping plug gap down to about 0.7/0.8mm (or get splitfire coils).

The reason this happens is because when air is pressurised it becomes denser, therefore more bost = thicker air. Standard plug gap works sweet for 7psi but any more boost requires stronger spark, otherwise the spark is extinguished by dense air. Reducing gap gives less distance for spark to jump so therefore it is less likely to be extinguished.

As far as being higher above sea level goes. Once you go higher the air gets cooler, cooler air means more dense air. Im sure you can figure it out.

Before anything else REDUCE your plug gap!!!!

[Iron Chef]

Not the rev limiter??

Edited May 18, 2006 by vrfour

[Smurf]

I have it on my car. It is all stock apart from exhaust. When they were tuning it they said that the boost was spiking and the computer momentarily cut power. They didn't suggest a fix.

Does anyone have this on their GTR or is just GTST's?

[ZERO]

heard from a few ppl already that its the sound running rich and retarded....

so what im going to do soon is put my computer in and i will update you guys again..

[ferni]

You all need to make sure you've gapped your plugs down to about .8 (drop it to .7 or even .6 if you have to) if you're getting a miss fire on full boost....

[MKDR33]

sounds like a coil pack problem..

Check --> http://www.skylinesaustralia.com/forums/in...howtopic=119403

Edited May 28, 2006 by MKDR33

[sam_33t]

hey ppl,

I was also having this problem with my r33, anything over 4000rpm and i would get a bad miss almost feels like its tapping on rev limiter. Today i took my coils out and inspected them and found 4 out of 6 couls had little hairline cracks in them. I taped these cracks up with electical tape (couple of layers), put the coils bak in and took it for a spin...there is now no miss at all, so the tape will hold for now untill i get new coils. So id suggest inspect ur coils, and look closely:)

[PHT33]

I just purchased new JJR coils for $399 from just jap, installed them tonight, and the missfire is worse.... So pissed. Do you need to run a smaller plug gap still? Only thinking this because plug gaps are engineered for most efficiency in igniting all fuel and oxygen in that cylinder...so...not sure about that. Also hit 1.57bar on the stock internals, thought id add that, these 33's are strong suckers...pity about all the damn teething.

[666DAN]

Missfiring R34 *ALWAYS* = coilpacks

My second R34, the first thing to get done on it was a set of splitfires....I never wanted to go through the frustration of those bloody things playing up ever again. Not doing them just wastes dyno time.

I always say to anyone buying an R34, always factor immediately a coilpack swap, the packs were just manufactured shit and don't last, no amount of electrical tape, silicone, gypsy tears will fix something that is inherent in the triggering circuit of these things.

Don't skimp on JJR bullshit, just get splitfires

[PHT33]

Added some new iridium plugs (0.8mm gap) to the equation, saweet as! It only had NGK 5's in it, was told to get 6's, even 7's. Ran with some 6's. Comes on in first, tire smoke, smashes second, tire smoke...etc etc, who ever though autos could be fun.