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Rb20Det Very Strange Misfiring

R33 0wnerrr
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R33 0wnerrr Enthusiast

R33 0wnerrr

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Before anyone says, yes I have searched and on many different forums

My rb20det was running fine one day, then started to develop a very bad miss on boost, so changed to NGK0.8gap copper plugs, new wasted champion spark leads, and the missfire continued.

A few weeks later after not driving the car, it was very hard to start, then when it finally did it sounded like it was running on 3cylinders, would idle but struggle insanely to rev past 3k rpm without sounding like a bee r limiter

I have changed the standard ecu, maf, injectors, plugs, leads, cas, a bunch of grounds, no error codes etc etc

It runs super rich backfiring if i manage to rev it past 3k rpm, but yet each cylinder has good spark and makes no difference when anythings swapped around

Oh and for some strange reason when the car has warmed up it runs better (running very bad still) to the point i can drive up and down the driveway, but it splutters and full boosts and wont get past 2500rp

Anyone have any ideas they could throw out? the car is completely standard except a straight pipe exhaust, pod

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JSF Apprentice

JSF

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I'm having the same issues at the moment, although mine doesn't seem as bad. My misfires around 3 - 5k rpm, still goes hard, but yeah is still misfiring. I've tried cleaning AFM with carby cleaner, changed spark plugs, changed fuel filter and my coilpacks are only 500kms old and they are splitfires. Going to try and put in new coilpacks and see how i go, :x. But yeah good luck with yours, if i find a solution and it's not one you've tried yet i'll let you know.

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R33 0wnerrr Enthusiast

R33 0wnerrr

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Yep please if you do find out let me know, Ive heard of the looms being the problems aswell but ive checked mine and it looks fine but maybe might be worth me changing it

And to the above posts, I have a wasted spark setup.... similar to http://www.skylinesaustralia.com/forums/topic/115690-wasted-spark-ingnition/\

so uses leads to go from the packs to the spark plugs, but this has been tested and is working fine also....

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Ben C34 Grand Master

Ben C34

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Sounds like coils dude. When they crap out it is under boost. when you say tested already what do you mean? just seeing if they spark? That's not enough to confirm they are working under boost/ higher revs. You need to swap them out with known good ones.

Edited by superben
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Ben C34 Grand Master

Ben C34

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Actually something else to consider is the dwell the coils require.

If you arent supplying the correct dwell, the coil wont be operating at its optimum, meaning when it craps out just a little it really craps out, if that makes sense,

I did an LS2 coil conversion, and with stock dwell it would misfire on boost (18psi) with brand new coils. Once dwell was adjusted with Nistune, miss went away.

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R33 0wnerrr Enthusiast

R33 0wnerrr

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Sounds like coils dude. When they crap out it is under boost. when you say tested already what do you mean? just seeing if they spark? That's not enough to confirm they are working under boost/ higher revs. You need to swap them out with known good ones.

Im not missfiring on boost, im missfiring constantly off and on boost at all rpm, its not a small missfire, this is huge, stopping it to even rev past 3k rpm,

its not running on all cylinders, cant even rev properly. The packs voltage it was sending out was test and found to be ok, ive also tried other coilpacks that are known to be working fine and it runs the same on this engine.... so i dont think its coilpacks

Edited by R33 0wnerrr
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kitto Mentor

kitto

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Just because a coil packs output voltage is ok under no load, doesn't mean it's firing properly under load.

What coil packs are you using? What part no plugs?

Have you considered it might be the igniter or CAS?

Is your fuel pump working ok? A dud fuel pump and or restricted fuel system will cause an engine to not run on all cylinders.

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R33 0wnerrr Enthusiast

R33 0wnerrr

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Ive swapped my setup and used a friends spitfires and they had the same problem in my 20det, same with his cas, and igniter. Have used BCPR7ES 0.8 and a set of iridiums

Fuel pump seems to be working ok, i presumed seeming it has been running rich backfiring extremely when rev'd up that its working fine, the injectors are all working and have been swapped also, but might try swap the fuel pump and see what happens?

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kitto Mentor

kitto

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Check fuel pressure before replacing it. Have you changed the AFM for a known working one? You havnt got a massive vac leak somewhere?

How does it run with out the AFM?

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R33 0wnerrr Enthusiast

R33 0wnerrr

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Ok good idea especially as I have a fpr lying around somewhere in the garage that i can hookup

Yep maf has been changed 3 times with working ones and when its unplugged it will stall. Ive checked all my pipes for leaks etc cant see anything

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al-himself Apprentice

al-himself

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im experiencing a misfire on full boost on my rb20, its running a gt3076r .82 rear housing mapped on a power fc, after about 5500rpm it misfires and hesitates.

also the cat temp light flicks on and off which im told is a pfc check light.

car was mapped and is boosting 1.3bar

I swapped plugs for bkr6evx11 iridiums.

what should I swap out next, coils loom and ignitor?

car runs fine apart from that, no miss on idle or out of boost.

in perth If anyone can help

Edited by al-himself
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