R33 S2 Missfire At 10psi +

[g0t pSi?]

Yes, I have searched...yes there is alot on the topic, I have read it all, I want specific opinions please.

Anyhows I have just put a Profec B onto my 33 and cranked the boost up a bit. Existing mods are:

*Blitz LM FMIC

*Apexi Pod

*XForce 3" Turbo Back

Still running the standard ECU and standard turbo. I have checked and tested the coil packs (still standard), there are in perfect condition, no arcing at all.

Now before putting the Profec B in, I put in some platinum plugs, heat range 6, which are pre gapped to 0.8mm (I am aware you cannot gap platinum plugs). I put them in replacing the plain NGK copper ones I was using and I found the platinum plugs to be better all round, much smoother, performed better in varying temperatures. Just based on this observation I find it hard to believe the missfire is an ignition related problem.

It is still running the standard fuel pump and although I will be replacing the fuel filter again this week, I doubt that would be the problem. Just as soon as the car hits high cam (about 4500rpm) on anything more than 10 pound is just starts spluttering like a little girl and even though it holds boost till redline, it just isnt smooth above 4.5k rpm. I have reason to believe it is running quite rich (just going by the ferocity of backfires while tuning the EBC) so perhaps the annoyingly standard ECU is the culprit.

I have an SAFC (one of the old school turn dial ones) sitting around, don't know if I want to bother with it though...I want to try and fix the missfire by spending as little cash as possible basically - I don't like getting robbed of top end performance. So what you guys would do in this situation?

- Throw money at a new fuel pump

- Throw money at a set of copper plugs and play with the gap (from what I have read 0.8mm is optimal and that is what the performance superior platinums are running...)

- Throw money at installing the dinosaur SAFC

- Rage quit on the car and burn it into a pile of rubble

Cheers all, appreciate responses.

[Richieb]

Coils..

[livedazzle12]

I use to have this problem I replace a spiltfire coil and twinpower hks yeh!! it can solve the problem. 100% it coilpack . when boost over 8 psi ecu will retard ignition and rich fuel then the standard coil can't spark as well.

[TTT]

2 things.

1.) how did you test the coils? how do you come to the conclusion that there is no arcing?

Did you remove the bonnet, remove the spark plug cover and strap your mate to the engine, go for a drive at night and load it up on second gear to 4500rpm down the road and get him to yell if he could see any arcing?

of course there's no arcing at idle or free reving.

there is no load.

2.) R33, stock ECU, 10psi, 4500rpm, misfire is as common as 14 second skylines.

If it didn't misfire at 7psi, and it does at 10psi, and you have new spark plugs, and you own an R33, you should look at the ecu.

Don't use the old AFC.

either get the original blue screen SAFC, or even cheaper, get the Jaycar Digital Fuel adjuster and hand controller kits and put them together.

but the SAFC is less hassle.

When I bought one about 3 years ago for the S14, it cost me $250 second hand.

since there have been a few new ones introduced, the original blue screen SAFC would be worth even less.

It'll cost you about $200 to get it tuned.

installing it is like 6 wires and come with instructions.

All this is if you don't want to spend about $1500 for a PFC or similar ecu.

your problem is ecu or coils.

probably ecu.

[LatinR33]

Sounds like coils, I know of a few boosted skyline running stock ecu's with 10psi and running great. I would still upgrade the fuel pump as you have boosted it past stock, extra insurance. Just my 2c

[g0t pSi?]

2 things.

1.) how did you test the coils? how do you come to the conclusion that there is no arcing?

Did you remove the bonnet, remove the spark plug cover and strap your mate to the engine, go for a drive at night and load it up on second gear to 4500rpm down the road and get him to yell if he could see any arcing?

of course there's no arcing at idle or free reving.

there is no load.

Something like that...on a dyno though and I can say that there is no arcing AT ALL. If what livedazzle claims is true though and the stock ECU just doesnt run the standard coils strong enough on higher boost, then a new ECU should fix the problem...

your problem is ecu or coils.

probably ecu.

Yeah I am thinking ECU too... I gave it a reset last night, but it hasnt made much difference, although the missfire didnt seem as bad in the initial 'relearning stages' (yes I know this could be interpreted as the coils getting warmer and arcing more - I will say again, I have not witnessed ANY arcing).

Oh well, $600 odd for Splitfires, $500 odd for an SAFC or $2000 for a Power FC/ECU solution. Gah, the money pit...probably the smartest thing to do is just *try* and be content with 10 psi until I scrape together for a new ECU

Thanks all.

[ashneel]

just my 2c

double check your coils. if you have the time (i did this and it solved my problem) get clear nail polish and brush it on your coil packs but put nice thick coats on so you will need two bottles and that should seal up the coil packs nicely.

if your getting misfires obviously its spark issue. most of the guys here are running 10psi or so on stock ECU and they aren’t having and problems with their boosting or misfiring.

Start with the small tests first that you can do your self before jumping in to a conclusion that you need a new ECU.

also i have NGK platinum plugs in my line also not sure of the gapping and its running perfectly.

so my guess is the coils or fuel pump.

[simpletool]

Well I'm in the same boat.

I have changed from platinum plugs (heat range 4!!!) to copper heat range 6. Changed fuel pump and filter (because it isn't a bad idea anyway) and have a SAFC 2. I have yet to fit and tune the SAFC 2. But judging from the fact that the longer I drive it the worse the misfire becomes (down to 3100rpm occasionally on 600km trip) I think the coil packs aren't coping well.

Now maybe when I lean out the mixtures a bit with the SAFC it will spark ok again. But I'm not holding my breath on this one - thinking I will need splitfires as well. As I'm back to running 8psi and although it doesn't misfire as intensely it does misfire quite regulary around 4500 - 5500 rpm.

Perhaps I should try the nail varnish trick? Is the problem fixable with the coilpacks, ie. is it the grounding of them? Or is it the actual coil packs themselves?

[ashneel]

Perhaps I should try the nail varnish trick? Is the problem fixable with the coilpacks, ie. is it the grounding of them? Or is it the actual coil packs themselves?

its the actual coil pack. it gets very fine hairline cracks on it and thats where the spark jumps from. so ye try it. i did mine overnight so it dried nicely. nice thick coats. did about 4-5 coats every 30mins. but when your putting them back in be careful not to chip and polish of.

its the most easies and cheapest test to do. atleast this way ou will know if your misfires gone you have a temp fix till you have enough saved for splitfire coilpacks.

[TTT]

couple of layers of electrical tape is a cheap way to test if there is any arcing issues that you can't see.

tape em up, go for a boot.

I did 3 layers when I had mine and it fixed the missfire issue.

considering it will set you back maybe $5 and an hour of your time, it's a worthy test before "new ecu" "new coils" "new tune" etc.

in the DIY section, there is a thread about this sort of thing and going one further by using spray on silicon spray that hardens up for a full seal.