Miss Fire After 4500 Rpm

[clkngezz]

hey guys just to get a few different opinions and see if anyone has had the same problem, i have a stock r33gtst s1, i just put a 3 inch stainless turbo back system on it, since i have done this, my car missfires after 4500 rpm, popping a fair bit, any ideas why it would do it know after exhaust is on? was not missing when i had stock exhaust on! could it be now that i have more air coming out intake there is less to ignite? im not sure just throwing some opinions out there to try get it sorted asap, have a few parts pending installation because of this

thanks guys

[sleepy33]

i have the same problem.. but mine only started after i put on my zorst, pod front mount and upped the boost..

i've been told that it could be the coil packs or the spark plugs need to be regapped..

not sure but ill do anything to get rid of it

[clkngezz]

i have the same problem.. but mine only started after i put on my zorst, pod front mount and upped the boost..

i've been told that it could be the coil packs or the spark plugs need to be regapped..

not sure but ill do anything to get rid of it

yeah mate, thats what it will probably be, im just very confused how it starts after a slight modification is done, i haven upped boost as yet! i need to get this sorted before i do that , i bought some new plugs and regapping them to .8 to see if that fixes the problem! if not ill try the next thing, probably coils, but when i change plugs i will leave rocket cover off so they can stay cool, see that also could be the problem!! to HOT? but its sooooo wierd for it to happen after exhaust fitted! so guys SEND HALP

[Slim Mat]

Hey,

Your exhaust could be too big, but I doubt it. We have problems with V8's doing it, putting a large exhaust on a standard engine, but only having a rough idle really. Some engines will be effected right through the rev range, but not usual.

It's more likely that you have a proper miss since it is happening over 4500rpm, under load right with boost? Could be plugs or leads.

[sleepy33]

yeah bud.. definatly let me know if the plugs work..

rather spend a couple hundred than a grand

cheers

[clkngezz]

Hey,

Your exhaust could be too big, but I doubt it. We have problems with V8's doing it, putting a large exhaust on a standard engine, but only having a rough idle really. Some engines will be effected right through the rev range, but not usual.

It's more likely that you have a proper miss since it is happening over 4500rpm, under load right with boost? Could be plugs or leads.

yeah very doubtful exhaust is to big! but hey im hoping its just the plugs or leads, when i got my 100k service im not sure if i got the mechanic to gap them, they are probably gapped at 1.1 mm, and there iridium ngks? so who knows i guess ill find out when i pull em out, and at this stage i just want a few different opinions, keep them coming, i know a guy who is really clued up on this stuff so he is helping lots to keep the opinions coming guys

[RB30-POWER]

more then likely the boost or actual airflow atleast has gone up and is tripping the airflow limiter in ecu (aka rich and retard)

lower the boost and you will find it will more then likely dissapear.

alternative is to fit powerfc or FCD/SAFC as a semi-perm fix.

[clkngezz]

rb30-power, yeah see thats what i dont think, its running stock boost :| so im not sure if it still can run r & r, i had a theory now that more air is coming out of the intake there is less in there to combust! in saying that the plug gap could be to big! i not really sure if thats right but its all i can think of myself , does anyone think its wierd that it happens less sometimes then other times if at all ?? wierd!

[RANDY]

Get up to 50-60 and put the boot right in. If it's a coil problem, it might happen at a much lower revs if you really boot it. (but don't speed... .back off at 70-80)

Mine did the same with a faulty coil and I could force it to happen earlier with an aggressive foot and too high a gear.

[clkngezz]

hey Randy, i did what u said this morning on the way to work! no miss at all, so i thought i would go onto a highway and go through the rev range a little more! still missing after 4500rpm but as i have said before, it misses sometimes more than others and sometimes not at all?? anyone else got any ideas?

[RANDY]

So... how stock is this? 4500 is where the dual stage solanoid switches from 5psi to 7psi... and I think the vvti changes over around that range also?

I couldn't accurately guess what the problem is... short from some kind of fuel issue (if your pump is semi-dead)

[clkngezz]

if it was a fuel problem, why would it arrise now that exhaust is on? but ur right could be that??

[RANDY]

Just a wild guess... exhaust allows the turbo to push harder at lower revs (earlier spool etc), but if the fuelling can't match it... problems?

Or if the car *is* heavily modified in terms of boost/cooler/etc, it could just be the rich and retard problem even? TOO much fuel? These are just really random and wild stabs in the dark. I don't think anyone could definitively say what the exact problem is without some element of a guess. (short from actually working on the car and diagnosing)

My money is still on coils though. =-]

An S14 mate of mine had the same thing, but then he put a tuned length manifold on and it went away. There are some strange, strange things that happen with cars. =-/

[clkngezz]

OK so i took my plugs out, which were ngk iridiums BKR5EIX-11 gapped at 1.1 mm , much to my surprise they were rusty looking orange after 8000kms of use? i dont think that is right, so a put in the NGK BCP6ES-11 and gapped them to .8mm or close to, when out for a drive and i have pretty much elimenated the miss, i can still feel the car wanting to go but something is holding is back, kinda feels like a miss but more like a slight struggle.

http://www.skylinesaustralia.com/forums/in...rt=#entry874231

this thread was very helpfull thankyou

i had a mate over so we took it back to my place, reset the ecu, then took her out for another spin once again very very very slight struggle/small miss, he had a theory that the car could be running very lean! hense the orange plugs, in saying this, my problem could be dirty injectors/dirty fuel filter/semi dead fuel pump/coilpacks, i did notice some type of resin on the sides of my coils, i think a previous owner did the cheap fix, i inspected each coil and couldnt find any cracks or splits so i just put them back in

at the moment im thinking fuel pump, because the miss only happens when it hits 7psi after 4500rpm my pump might be struggling ???

i will be running a few bottles of injector cleaner through it over the next couple weeks to see if that improves the high rpm!

let me know your thoughts guys very eager to get this sorted, and maybe help a few of u other guys out

adam

[TTT]

Always try the cheap things first.

any increase in flow (exhaust, intake, boost) will bring out spark issues.

new copper plugs are cheap @ $4 each.

gap to 0.8 as above.

I also taped my coil packs up with electrical tape ($7 for a roll of good quality 3M branded stuff)

I pulled each coil pack out and started down the bottom (the part that goes OVER the spark plug).

I went up, then down, then up again and ended it up the top (at the very top of the actual COIL)

As I wrapped it with the tape, each turn went over half the last turn so it was a tight, thick layer.

this completely removed the misfire.

Mine was on an 1989 R32.

so it was 18 years old with factory coils.

since the above will only set you back like $30, if it doesn't help (99% of the time it will), you have only spent $30 and besides, you now have brand new spark plugs and sealed coils for when you do find the problem.

New pump and filter are always a good idea on a modified skyline.

if you are not looking to change the turbo, then a WALBRO pump for like $170 is enough.

People say they don't flow well under high pressure but with your stock turbo in an RB20 you'll get like 170rwkw if you're lucky and about 200rwkw on an RB25...

the pump can handle that.

also get a new fuel filter to make sure.

Not sure about the off the shelf injector cleaners..

nor do I know how much it costs to get them taken out, ultrasonically cleaned and flow measured.

I'd say more than the above costs though..

If these do not fix the misfire issue, then it will be R&R issues that R33 owners have..

search for threads by user WOGSRUS...

he's had 1 or 2 misfire threads..

[700HP-GTR33]

hey guys just to get a few different opinions and see if anyone has had the same problem, i have a stock r33gtst s1, i just put a 3 inch stainless turbo back system on it, since i have done this, my car missfires after 4500 rpm, popping a fair bit, any ideas why it would do it know after exhaust is on? was not missing when i had stock exhaust on! could it be now that i have more air coming out intake there is less to ignite? im not sure just throwing some opinions out there to try get it sorted asap, have a few parts pending installation because of this

thanks guys

All the above can be true.....

It can also be your afm....at fault..etc etc

I have a stereo,aircon,lights and all the goodies in my car....I was always missing at night at 3700rpm.

Changed the battery to a heavy duty type...biggest I could fit and walla...no miss

It sound like an electrical fault....could be loom,coils, etc etc...not to mention battery

Good luck....

[clkngezz]

ok i have now tried the taping of my coils as the DIY thread says, still hasnt elimenated my problem, when it hits 4500 rpm and after to about 6000 rpm it feel like its trying to go but cant then after 6000rpm it picks up for a second till it almost hits limit! my next thoughts are that i may need a new pump to help with the extra boost in high revs? what do you guys think, if my fuel pump still doesnt fix my problem, i will have my safc/fmic/boost controller/boostgauge/all fitted by then, if the safc doesnt fix it either, i will try new split fire coils!

i was also thinking of just going to get a new o2 sensor?

what are your thoughts guys!??

need help

[craked]

Its not the o2 sensor standard ones dont read after 3000

step one borrow an air flow and try that first as it wont cost anything the air flow meters do sh*t themseleves but i think will find the new exhaust has allowed the engine to brethe and the boost hads more than likely picked up 1 or 2 pound s1 coils are really sh*t even if you replace and regap the plugs it proabley wont fix it get spit fire coils and ngk plugs and that will do the trick

Edited July 4, 2007 by craked

[clkngezz]

ill try the air flow meter, ta, i have new ngk .8 gapped plugs, so if the flow meter, doesnt do the fix, split fires are coming my way , thanks craked,

anyone else got any ideas

[joeyjoejoejuniorshabadoo]

i have this in my 93 33gtst

its DEFINATELY the coils (have checked them)

with non restrictor plugs gapped to 0.6 and a power fc the problem is gone... although i dont spose a $1500 ecu is a cheap fix!

either way spitfore coils comming next