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

Nightman

By Nightman,
in General Maintenance

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SLY33
SLY33

developed a pretty bad miss from 4grand up, well its more like a rev limiter sound after 4 grand! other than that it drives normal. Suspect its a coil or even 2 coils seeing as the miss is so bad. I

GTofuS-T
GTofuS-T

MrStabby just posted this video in a different post and thought it was very relevant to this thread. (Can't seem to embed it) http://youtu.be/Qirx_G4x5i0

Mitch_Dubya
Mitch_Dubya

Here's a pic of the coil that was arcing out on me. Running down the side and arcing to the head of the bolt.

Posted Images

Links Veteran

Links

Posted
Posted

Quick question ppl..

Can someone describe what this feels like when occuring..

Went for a drive on sat in an R33 - in second car would hit about 4,000 - 4,500 than for a split second it would lag/pause/slow/stop/cruise however you want to put it for about 500rpm than it would kick in again and race to redline..

is this the same issue.. talked to the guy and he said "most likely fix it by adjusting the timing".. wasn't sure about that, seems to be the same issue as this..

didn't hear any missing, didn't feel like it.. just kinda paused for a second than came back on the power..

benl1981 Grand Master

benl1981

Posted
Posted

I'm having some trouble. Put new spark plugs in gapped to 0.8mm. I thought the coils looked ok. Couldn't see a hairline crank on the front, though maybe I missed it. But most of the coils had stange bits on the side where it looked like they had seen lots of heat.

Just lately I get a misfire, well more like a boost cut but it happens at just above 3000rpm up a hill in 4th gear at 0.65bar (about 9.5psi).. I thought maybe it is the ECU sensing too much airflow and going rich and retard. But I thought this was at more like 12-14psi...

Can somebody have a look at the pics below..not the best but gives an idea of the what is going on on the side. I heard somebody in the thread saying the heat on the side may be from arcing?

img01967ss.jpg

img01972ln.jpg

  • 2 weeks later...
SideWaysChef Collaborator

SideWaysChef

Posted
Posted

I did a decent job of taping my coils up, worked fine for about 1 week

then back to the same old crap of laggin round 4500-5000rpm

have since poured some octane boost into a 1/4 tank of petrol and it now revs straight to 7500rpm

definately think the coils can be a bit of an issue but is more likely due to poor octane ratings of aussie petrol

just took my car for a thrash with the boost wound up to about 1 bar and it is still loving it

why oh why dont they sell some decent petrol in australia

kezza Proficient

kezza

Posted
Posted

hey, I had the same problem for 3 weeks. it started off, missing and shitting its self around 4 to 6 tho.

And as the weeks went by it got worse, anything over 2 grand made her crap on!

i pulled out my coil packs and a few of them were marked like were you can see spark has been jumping out of the side of the coil..

i checked the plugs, they were alittle but crap from fule not being burnt.. but i cleaned them and wacked them back in.. and slipped in some new split fire coil packs in..

took her out for a belt and it works fine now, up around 6 and a half grand she splatted once but i have noticed a big jump in get up and go!!

Oh and idling is HEAPS better, it used to surge a little, now gone..

The only other thing im going to do next is take the AF sensor out and spray some contact cleaner on the sensor part, Im sure that will help a little bit too..

the last time i cleaned out my air filter, i think i used too much oil in the filter, and if it gets on the sensor it will cause it to faul up !

So i think a few of my coils are still fine, ill have a good look at them and test the ones that are good, and if anyone wants to buy some off me they can..

[email protected]

SideWaysChef Collaborator

SideWaysChef

Posted
Posted

Have any of you guys had you computer's remapped to run on 98 octane petrol

would like to hear any experiences people have had after getting their ECU reprogrammed

Coils seem to be part of this problem of missfiring, but im sure the low octane ratings of aussie petrol are having a significant affect on performance

Most of this cars would be running on petrol with octane ratings of 100 or more in japan

Cubes Grand Master

Cubes

Posted
Posted

From what I understand jap fuel is 100.

2 points doesn't make a big difference.

The majority of people do not have issues with missfiring.

It is definitely not the fuel, rather the coils.

My PowerFC's base map ran aggressive ign. timing at WOT.

It only made the thing ping its head off, no miss-fires.

However, there is such a thing has a lean missfire. Run the car lean, it will detonate then get to the point where there isn't enough fuel and will begin to missfire.

Bazelinez Proficient

Bazelinez

Posted
Posted

Took my coils put today and 3 were split on the greay part surrounding the metal thing. Very technical eh? Taped them up but in thr process I noticed a shitload of green calcium build up and general crud up inside.

I took a Dremel (small high speed drill thingy) and lightly ground the inside of each coil pack until it was shiny again. I already had new springs inside and I screwed a tiny allen bolt up the guts of each spring to replicate the factory set up.

In all I had about 3 teaspoons of carbon/calcium/crud I removed from all the coilpacks.

Result is fixed mis firing, stronger performance, better idle. :rofl: Worth the effort if you have the tools.

Zahos Mentor

Zahos

Posted
Posted
Took my coils put today and 3 were split on the greay part surrounding the metal thing. Very technical eh? Taped them up but in thr process I noticed a shitload of green calcium build up and general crud up inside.

I took a Dremel (small high speed drill thingy) and lightly ground the inside of each coil pack until it was shiny again. I already had new springs inside and I screwed a tiny allen bolt up the guts of each spring to replicate the factory set up.

In all I had about 3 teaspoons of carbon/calcium/crud I removed from all the coilpacks.

Result is fixed mis firing, stronger performance, better idle. ;) Worth the effort if you have the tools.

http://www.skylinesaustralia.com/forums/sh...?t=51046&page=2 post #57

No need for Dremel tool.

Just spray some WD-40 or CRC-50 on them and it washes off instantly!

Then just rub inside with a bit of steel wool for a few seconds and they are right to go.

kezza Proficient

kezza

Posted
Posted

well, i can say after puting in the new coil packs. It went alot better, but it has come back!!

noooooo, but not as bad! it feels like when ya in 4th and you power up alittle it hits this ,,, like flat spot, but its a miss spot! thats when it starts to piss me off..

I took the AF meter off, and sprayed a heap of contact cleaner(the one that desnt leave a resadue) and let it dry... but still doing it!!

ill change the apark plugs on the week end, and if that desnt fix it... well im going to sell it and get a holden

Zahos Mentor

Zahos

Posted
Posted
nah mine did not come out with just degreaser or anything. Its easier with a high speed buffer anyway :thumbsup: Mine were well and truly stuffed...

To do one of them with steel wool wrapped around the end of a drill bit (I know it's no dremel tool) took me a few minutes, and there was still some left...

To do all 6 with WD40 took 30 seconds. I then used the steel wool to clean any residue. Spraying degreaser will do nothing, you need to use WD40 or CRC50.

WD40 is much easier.

Bazelinez Proficient

Bazelinez

Posted
Posted

reagardless, the car runs fine now and the packs are nice and shiny. How ever its done doesn't really matter. I tried with all sorts of cleaners last time, they did sfa. I think after 15 years it was beyond it.

The dremel took 5 seconds on each coil to bring them up like new so I still stand by the method if you have access to one.

whatever works for you :rofl:

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