Missfire Boost@4500-5500 RPM - The Answer! (for me at least!)

[R33S2]

There is a Qld section of this forum. What is your plug gap and boost?

[HotPlates]

I can't get to my plugs because I can't disconnect the the loom plug. I can't get it off and I don't want to break anything!

There is a clip on the top, but do you push it down or lever it up? Either way I still can't disconnect the stupid thing!

[HotPlates]

Fixed. Mods please delete above post.

[DR-JEKL]

I went to Sydney to look at a few 99 R34 V Spec GTR's with a mate today he picked one out and we took her for a 'test drive'.

The car started fine idled fine, didnt blow smoke, wasn't running rich when cold, everything seemed great.

We hopped in went for a spin and from 2-4k rpm in any gear when cruising. It was coughing and farting like a $200 TX gemini running on sugared unleaded, but when giving it a squirt & hitting boost at 4k rpm the misfiring disapeared & it pulled nice and hard to 7-8k rpm.

Most cars that I have either heard of having misfiring occurs when the car hits boost at 4-5k rpm on a hot day, but this thing as soon as it hit boost smoothed out and pulled hard to redline in 1-2nd gear and idle smoothly also...

The car looks to have a genuine 25000 kays (its in mint condition) and just has minimal mods (pod filters, hks exhaust from the turbo) as far as we are aware its running stock boost, stock turbos and a stock ecu.

Obviously the car has been sitting around for 6 months or maybe more, and may just need a new fuel filter plugs and a new tank of juice.

Could a fuel pump cause this problem? coilpacks? timing? loose i/c hose clamps?

The car is booked for a full checkup on Wed, but it would be good to hear if any other forum members have had similiar problems?

Edited June 28, 2008 by DR-JEKL

[DR-JEKL]

Anyone out there?!?!?

Seems a bit dissapointing that a forum such as SAU is full of members with a wealth of knowledge, but not willing to help out a noob.....

[Gaspard]

It worked for me (S1 Stagea RB25DET):

Tape -- Free (from my toolbox)

1 hour labour -- dirty and annoying, but also free

Not misfiring!! -- PRICELESS!

-G

[rhys5169]

sorry can anyone point me int he direction of where to look and tape? im pritty sure ive got the same issue, when its cold i get a miss fire from around 4k......

cheers

rhys

[rhys5169]

ok so just taped every coil, the problem is a shit load less prevelant, but it is only backfiring in 1st gear when i turn right, this is the only time it has done it and only gear, i just spent the last 2 hours out there testing and fiddling!???

wat the heck does this mean?lol

[polishboi]

i had this problem and i originally had 1.1mm gap so just the standard gap for this plug then i gapped them down to 0.75mm it removed my problem for a while however now upgraded to a slightly larger problem has caused the same problem so im getting splitfire coil packs cant go wrong with them :-D

[Luciano]

this problem has been truly giving me the shits for a long time in the 33.

I originally dropped in BCPR7ES sparkys gapped at .8; it slightly solved the problem. You could still feel a bit of loss in power above 4000rpm.

After i installed a FMIC, in the cold weather shes boosting around 12psi, and the missfiring is a hell of a lot worse.

i'm going to try this coil pack taping over the weekend and post the results...

If i can truly nail it down as the coil packs being the problem, next investment for the car = splitfires

[Luciano]

Carried out the work today and took the 33 for a drive; no more miss! Fantastic!

a couple of the coils had scorch marks and even minor plastic melt. definitely time for a new set

[jutstar]

When mine developed a miss, I tried the taping trick, didn't work, re-taped - worked for 2 minites, so I've ordered some spitfires.

[kat_00seven]

Hey guys, just thought i would say great post. Very informative and usefull. I sugest people read the whole thread first before they post a question though, as alot of them were already answered before the new post was made. Anyway as i see it maybe some actual pictures would help people get a better idea.

I have recently bought a R33 from the importers, it had a miss when trying to run boost any higher than stock. I changed the plugs they looked like the original units from the factory lol but then u expect platnium plugs to last 80-100k and mine had 90k on the clock. Anyway changed plugs with good quality NGK platniums 1.1mm. Still had the miss but i changed the plugs at night and never got a good look at the coil packs. After reading this thread i pulled them out, every coilpack had arcing scorch marks on the sides and i araldited them all see attached pics before and after.

So far so good, pulls hard through to redline without any misses @ 0.85 Bar (12.3psi) big improvement and i didn't have to regap my plugs as im hesitant to do that. would rather a dyno tune once i get my dump and front pipe on and my front mount intercooler happening. get my A/F mixture right and it should help the stock coils alot.

Don't underestimate Aryldite, i once used it to patch up a bolt sized whole in the magnesium alloy engine casing on a Honda XL 250 motorbike. Last i heard it lasted 10years without any problems and still going strong :-D yay for bodgy backyarders ROFL (jk i plan on geting splitfires when my exhaust and frontmount intercooler are on)

[ian_and1]

Hi guys

just wondering if i could grab some advice, i have the same problem in my R34 now i have pulled out my coils and they are perfect no cracks or anything like that, taped them up just incase, now i was wondering could it be the ignighter in one of the coils that could be causing me problems ? it also back fires pretty loud sometimes between gear changes ?

[ian_and1]

any-1

[ian_and1]

well i just went and got new coils fitting them tomorrow will let ppl know if it was them or not (hope so )

[ian_and1]

FIXED

[Rolls]

Another cause can be the car running way too rich, this will exasperate the cracked or worn out coils. I've heard of people having this problem with f**ked coils and then getting a re-map from 10:1 to 12:1 and the problem going away.

Edited November 29, 2008 by Rolls

[ian_and1]

yeah well it's still doing it gonna go change plugs have a look over, but im running out of idea's

[julz2bit]

Hi i have a r34 and for some reason it goes into somthing like a limp mode where its only firing on 3 or 4 cylinders , Ive just replaced oxy sensor and plugs and 2 coil pack have been repalced ive cleaned the air flow meter aswell . Could it still be the coil packs ? I so run out of ideas . Because Its happening twice a day on the way to work and then on the way home. I used to be able to restart the car 4 times and it would be ok but now that doesnt help. The only other thing that happens is my slip light comes on and trac control light and the engine light and abs aswell. I went to the auto elec and he pluged his computer in and came up with a error 21 ? dont know what that means . Can somone please help.