r33 misfiring ?

[DJ_L3ThAL]

hi guys

ive had this problem since i started 'modifiying' my completely stock from the start r33 95 gtst

current mods

full exhaust and high flow cat

safc2

boost (10psi.. want 12)

pod

front mount intercooler

ngk platinum spark plugs

evertyhing else is 100% completely stock engine etc wise.. i have mags etc but they are negligible for the problem i have...

so the problem...

when i give the car full throttle or even really 85%-100% from anywhere (from standing or whilst driving.. dropping gears etc) i get this weird un-even popping around 4k-5k RPM and i feel a significant power loss.. ive been told its misfiring.. i think spark plugs were gapped to the stock height (1.2mm) so i was thinnking perhaps lowering them to 0.8mm might solve the problem ? it seems to be worse the more boost i give it.. iots really shitting me i just want my car toi be nice n smooth right through the rev range to the red line in all gears.. copz it goes pretty hard its just i dont like to do it in case im damaging the car... what could it be ? how can i fix etc ?

cheers boys

[whistla]

I had the same problem

once i regapped some new plugs in at .8mm the problem stopped

Heres a pointer though, forget about these fancy shiney what not ngk platinum spark plugs

Just use copper plugs and change them every 20thou or so kays, the car will run better and smoother all the time

Key some tools, a plug gapper and do it yourself

[GTST4G]

Sounds to me like a coil problem. I have seen it on most of my mates 33's. Of ocurse I would try a new set of plugs regapped to 0.7-0.8 first, as these are a great deal less expensive than coils. If all else fails a new set of coils is on the cards.

Oh yeh on all my mates cars the only time it happens is when the boost is increased.

Bad news is that coils are expensive. Look around $1200 for factory replacement or something like $900 for splitfire.

Cheers

[DJ_L3ThAL]

yer i was hoping the coils werent the problem... well ill tell the guy to regap them to 0.8mm tomorrow morning and ill see how i go with that... if that doesnt work or if it reduces it slightly ill get some coppers and try those.... if not i guess ill have to find which coils are playing up and replace accordingly :S DOH!

[whistla]

when was the last time u change your plugs? (kays)

same goes with the fuel filter...

[DJ_L3ThAL]

the plugs were about 4000 k's ago (only had the car for about 8000 tops) and never done fuel filter.... which fuel filter do i need ?

[slayer_1971]

yeah...I've also currently got the same problem....just waiting now for some coil packs to come through the post. Hopefully this will fix it...

[predator]

u need a Z201 or Z200 filter from repco.. but itz prolly not tha filter

[DJ_L3ThAL]

slayer how uch werre they /were u get from

yer gordo i agree but ithink it neds doing lol

[whistla]

the filter may not be the problem, but its a contributory problem

there is no harm in changing it

u may as well do plugs and fliter first before u go to the extent of changing the coil packs

iv seen this problem all too often, and its always the simplest option (which is the plugs or injector cleaning)

then when those options fail, test the coil packs

[Driver]

I have the same problem, my mechanic said its the coil packs but its hard to tell which one it is on mine since it doenst happen all the alot, and i dont wana pay to get them all replaced.

[TTT]

Do a search in this section for "misfire"

you will see, that 90% of R33 GTST's have this problem.

once boost goes over 9psi (that is the lowest I've seen this problem) they get a miss at about 4500rpm or about there..

re-gap the plugs to 0.8mm and the problem will go away.

it is very common.

also, in regards to the coil packs.

One of mine died and I bought one off these forums for $40.

never had a problem since.

Wreckers sell them anywhere from $60 - $100 each.

I belive that the spark plug gap will fix your issue.

make sure that you do the plugs ONLY then go for a drive.

that way you will know that it was the plug gap.

then I would also recommend you do the following just for good measure.

**clean your AIR FLOW METER (take it out and spray carby cleaner on to the wire in there... let it dry. it will evaporate on it's own).

**if you have a re-usable filter (pod or panel) clean it (cleaning kits are available most auto spares shops.

**change fuel filter.

it's like a cheap service on the most used parts..

considering that you had an oil change 4000kms ago, you can wait another 1000kms before the oil and oil filter are replaced.

good luck.

[slayer_1971]

I'm getting them from another forum user in Sydney

[DJ_L3ThAL]

well re-gapped the plugs today and put my pod filter on (was running just with AFM.. but still had the problem before anyway when ihad the olds pod on)

AND ITS ALL GONE!!! w00t im so happy i gave it a test drive near the workshopa dn it was fine and booted it occasionally on the way home and its all fine. dropped the gap to 0.8mm gunna gop for a few more runs later tonight but im pretty sure its all sweet now... but still i think i might get the injectors cleaned (is it good preverntative maintenance ???) and change the fuel filter on my next oil change (shouldbe in about 3000ks)

thanks for your help guys

[whistla]

Good stuff...glad it all worked out

[TTT]

man someone should put up a sticky post in this section about misfiring in the R33's.

it is almost ALWAYS the spark plug gap.

[DJ_L3ThAL]

[anish maharaj]

same problem here.. hopefully it will be resolved swiftly and cheaply

[Guest mort]

When the coils on these things playup you generaly find that the affected cylinder will drop out when the car is hot and at idle, all rb twin cam engines will suffer from this at some stage, second hand coils are fairly cheap at around $60ea but you only need to buy one to fix the problem. The igniter on the back of the rocker cover is also another problem area.