ECU cut out/Boost cut at 9.5psi?? Or faulty coils? R33

[benl1981]

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 would be 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?

[benl1981]

Can somebody help out if they know...thanks

[Panikin]

Looks like your coilpacks are rooted (the burn marks on them are a tell tale sign of this.). try some without those marks where the spark is esacaping or buy Splitfires if you have the funds.

[benl1981]

Really! Most of the 6 have the burn marks on the side. I don't know if you can see but it also looks like there is glue in little patches on them. Is this something inside that has leaked?

So that is where the spark is escaping you think.

Sometimes when you rev it out you can feel the power fluctuating, almost missing.

Just lately got that what felt like a boost cut..

[benl1981]

anyone else? any ideas. Thanks

[benl1981]

Seems almost perfect on 7psi, some slight hesitation yet turn it up a little and things turn nasty...

[rd-runr]

I get boost cut with standard coils at 12psi.

At 10 psi floored, I get popping!

[benl1981]

THe popping is just extra fuel right?

[rd-runr]

Yep!

[benl1981]

So you think at 10psi I shouldn't be getting a cut due to the ECU???

[Panikin]

the plastic gets brittle over time and cracks appear however small they are there, the spark jumps from under the cradle to the metal (just a note i used hi temp gasket silicone as a quickfix until funds for spiltfires are available). My car was fine on stock boost any more and it felt like crap and sputtered badly.

[HKS-R33]

I was having the same prob. On 7psi it was fine, 12psi and it would missfire at about 4000rpm. Checked the coil packs and they all had the burn marks down the sides. I changed the coil packs and all is good now.

My guess is ur coil packs are stuffed, maybe try and get a lend of someone elses to try it out

[benl1981]

Thanks fellas.

Mine really feels like a boost cut though..feels almost like a rev limit. Really just kills all the power. Is that what you guys are calling a misfire? I think I just back off straight away aswell as it doesn't feel good.

So Panking - do you think mine are cracked on the side rather than the front where most people find cracks?

[blackrb20silvia]

my rb20 does this to only sometimes but at 15psi its bad at 10psi there is nothing but i do have a big T4 turbo and have been told this seems like airflow meter cut,

and its not coils these are brand new so sorry added another possiblity to your saga

cheers

matt

[siksII]

Thanks fellas.  

Mine really feels like a boost cut though..feels almost like a rev limit.  Really just kills all the power. Is that what you guys are calling a misfire?  I think I just back off straight away aswell as it doesn't feel good.

So Panking - do you think mine are cracked on the side rather than the front where most people find cracks?

hey, i have a series 2 skyline (the coilpacks are different to series 1 so may crack in different areas) and 3 of my coilpacks were stuffed, they had burn marks on the side just as yours did.

a way u can see if they are arcing (spark escaping) is to get the car hot then park it somewhere dark open the bonnet and u should see small sparks around the stuffed ones, this is the spark arcing to the head/bracket around the coil.

when mine played up, they did way more on 9psi than they did on 7psi i knew it was coils/plugs because i have pfc (no cuts)

the sound mine made was a high frequency popping noise out the exhaust, which was all the extra unburnt fuel burning on its way out.

try the test i mentioned above see if u can see sparks, u can try and araldite them or tape them up to fix it but that usually does not last long, and it looks as though someone has tried that already on your coils.

and yes it feels like a rev limit just as you described, it does not feel like it wants to rev any higher.

[benl1981]

Hey thanks siks!!

So you can see the small sparks at idle once warm? I'll have to run it without the centre cover I guess. I might leave that off anyway to stop the coils getting so hot.

Feels like a fuel cut but hopefully is as you say as about 5 of my coils had those burn marks.

[siksII]

Hey thanks siks!!

So you can see the small sparks at idle once warm?   I'll have to run it without the centre cover I guess.  I might leave that off anyway to stop the coils getting so hot.

Feels like a fuel cut but hopefully is as you say as about 5 of my coils had those burn marks.

all of mine had burn marks, however only three were arcing.

yes u have to leave the cover off so its easy to see. i know people who have left the cover off which has improved the missing problem. i think you will find that the hotter the car is the worse the problem is. also it will miss more depending on load ie very easily in 4th gear.

anyway get the car hot then have a look and see how it goes.. make sure u go somewhere really dark so its easy to see the sparks. u can give it a good rev while watching to get it hot/under a bit of load that that may help, although i found just letting it idle was enough to see the arcing.

[benl1981]

Yes I found 4th to be the main problem. I'll check it out tomorrow afternoon.

Thanks for the advice. So you only replaced the ones that you could see arcing the other burn mark ones you left in?

PS. Can you get to all the coil packs without taking the plumbing off if you leave that cover off. I.e. does the plumbing stop you getting to No.4 or 5 coil pack.

[siksII]

Yes I found 4th to be the main problem.  I'll check it out tomorrow afternoon.

Thanks for the advice.  So you only replaced the ones that you could see arcing the other burn mark ones you left in?

PS.  Can you get to all the coil packs without taking the plumbing off if you leave that cover off.  I.e. does the plumbing stop you getting to No.4 or 5 coil pack.

i tried taping all of them, then covering all of them in araldite, which did not make it much better once the car got hot... so finally gave up and bought a set of splitfires

if the cover is off, you can definetly remove all the coils without touching the plumbing. (another reason to leave the cover off, laziness )

[benl1981]

Thanks again. I'm just worried that some won't be acring at idle yet at 9psi they may start to.

Or do you think you would see a small amount of arcing at idle to show if one is had it or not...