Spark Plugs And Gaps

[mii11x]

firsty the car is making 236rwkw with an rb25det series 2, garrett 3071, power fc, 555cc injectors, 19psi etc and began making a misfire when i hit about 4000rpm on full throttle. i could lightly use the go pedal and creep up on boost but the misfire seemed only when throttle was mashed to the floor.

was in need of service so while doing oil etc decided to change plugs. they looked fine and even through out 1-6 when i pulled them out. i made the mistake of putting back in platinums with a 1.1 gap (heat range 5) and the problem became worse. like really bad pretty much had to drive around off boost. anything above say 50% thorrle gave a misfire and a continuous one at that. i thought it might be coil packs but read the forums and found out that the higher power output from standard the gap of the spark plug should decrease. i was unaware of this.

changed the plugs back to the standard $5 plug and gapped them at the 0.8 which seems the norm for most people on here. guess what.........problem has been pretty much resolved. it slightly misses once at about 4000rpm but other than that i can make full use of the power the car has.

any other ideas about what could be causing this slight misfire still. not that its a bad miss(compared to the old plugs and the platinums) more like a clearing of the throat quickly, but it shouldnt be there as it never was when i got the car back after having the upgrades done around 14months ago(bout 12000km's). i should have tested the resistance on the packs but it became dark, might do tomorrow if i have the time.

any ideas

mick

[blind_elk]

Because you are making more power than standard, you might like to try a heat range 6 plug, gapped down a bit, say 0.9 .

[AngryRB]

1-standard coilpacks should be replaced, there old

2-whats going on with that power output? thats a low figure for that boost isnt it??? i was recently speaking to MTQ and they were talking about a guy that made 300kw with a gt3071, but surely atleast 260kw's is expected.

Edited June 23, 2012 by SliverS2

[Dobz]

1-standard coilpacks should be replaced, there old

2-whats going on with that power output? thats a low figure for that boost isnt it??? i was recently speaking to MTQ and they were talking about a guy that made 300kw with a gt3071, but surely atleast 260kw's is expected.

+1

Also do as blind_elk stated, get at least a heat range 6 plug with a 0.9mm gap. Get it back on the dyno and get the tuner to sort out the tune because unless you have noticable intake or exhaust restrictions you should be making around 260kw with that setup.

[rondofj]

I still believe one coilpack could be still out, if u have a friend with the same car, swap the coils over and see if it solves the missfire, i had exactly the same prob, bought new coilpacks, prob gone completely

[boostn0199]

I would go the bcpr7es at 0.8 if 19 psi but if there old coils they could be getting tired.

[mii11x]

Because you are making more power than standard, you might like to try a heat range 6 plug, gapped down a bit, say 0.9 .

the fella at auto one suggested these also.....think he said they were in the platinum range

[mii11x]

1-standard coilpacks should be replaced, there old

2-whats going on with that power output? thats a low figure for that boost isnt it??? i was recently speaking to MTQ and they were talking about a guy that made 300kw with a gt3071, but surely atleast 260kw's is expected.

+1

Also do as blind_elk stated, get at least a heat range 6 plug with a 0.9mm gap. Get it back on the dyno and get the tuner to sort out the tune because unless you have noticable intake or exhaust restrictions you should be making around 260kw with that setup.

he did tell me if i wanted a power figure he could get me the 260ish. he said it was tuned really safe and also by lunchtime it was 40degrees(i was there watching the tuning on the dyno). i dont think i ever put the graph on the critique my tune section, so maybe i should, or maybe post it here if your keen to check it out.

i was a little dissapointed at first but glad it made that(236) as the old engine had done 340000km's so it was a massive improvement for me. but now i am thinking of going for more power so i will need to contact him, however i dont know where he has moved to. Not sure if i should say who tuned it now, but i was extremely happy using him to do all the work for me and he is pretty well known amongst silvia enthusiats. i would recommend him to anyone as i had no nonsense with him doing the work for me, we sat down at the start of it all, what i wanted to do with the car etc, then questions bout parts etc. he came back to me with some options and rough extimate and was very helpful with all my questions. didnt exceed my budget by too much which is always good.

[mii11x]

I still believe one coilpack could be still out, if u have a friend with the same car, swap the coils over and see if it solves the missfire, i had exactly the same prob, bought new coilpacks, prob gone completely

ill prob be checking them out tomorrow and testing the resitance to see if they are still fine, if they arent well ill buy the splitfires. looking to get a new loom while im at it also

[DVS JEZ]

ill prob be checking them out tomorrow and testing the resitance to see if they are still fine, if they arent well ill buy the splitfires. looking to get a new loom while im at it also

Resistance wont tell u a thing.

U can try gapping the spark plugs down to .6mm or

Get some splitfires

[mii11x]

Resistance wont tell u a thing.

U can try gapping the spark plugs down to .6mm or

Get some splitfires

so even if the coilpack is rooted the value will still read in the 0.6 - 0.9 range??? im waiting for my mate to buy some splitfires which isnt too far off, maybe we can get a discount if we buy two sets, dont mind spending cash but if i can save a little i will.

[WMDC35]

the resistance test won't load them comparatively, 340ks!

[mii11x]

the resistance test won't load them comparatively, 340ks!

yes the original rb20 had done that many km's. thats what it read on the odometer when it was removed. it still ran ok

[MrStabby]

so even if the coilpack is rooted the value will still read in the 0.6 - 0.9 range??? im waiting for my mate to buy some splitfires which isnt too far off, maybe we can get a discount if we buy two sets, dont mind spending cash but if i can save a little i will.

There's more the the coilpack than the primary winding. So, if the primary winding is NOT 0.6 - 0.9, you KNOW its stuffed. If it IS 0.6 - 0.9 it MAY or MAY NOT be stuffed. Or to say it another way - that check can only confirm that its broken, not that its good.

If you can see any arcing marks, use the coilpack fix from the DIY. It addresses another issue that can go wrong with them, that is, that the insulation has failed.

[JonnoHR31]

Gap the plugs down to .6, if the miss goes away then be happy. If it doesn't make any difference then something else is up and your coilpacks are probably no good. Much cheaper (free if you have the tools) to simply gap the plugs down before you go changing coilpacks or anything else.

[mii11x]

yeah hopefully be able to try .7 gap this week, and i will check the coilpacks too with the multimeter. if i do get the splitfires is this considreed a mod to have the car retuned???

[W0rp3D]

How much of a difference does the heat range make, im running 22psi and its breaking down up top, im running 6's at .8 any idea if 7's at .8 would fix it or should i go straight to 6's or 7's at .6?

[KiwiRS4T]

If you're getting down to 0.6 gap its time to look at your coils. I have new OEM coils running BCPR7ES at 0.9 20psi (280kw) going up to 25psi soon - no missing.

[W0rp3D]

If you're getting down to 0.6 gap its time to look at your coils. I have new OEM coils running BCPR7ES at 0.9 20psi (280kw) going up to 25psi soon - no missing.

That thought has crossed my mind, i have fairly new yellow jackets but maybe its time to get some splitfires.

[mii11x]

i ended up getting new oem coilpacks from adam on here (rbceffy25) and installed them two days ago. my car is now running like the day i got it back from the conversion, upgrade and tuning work. its running sweet as now, all the power is back. my old coilpacks had scorch marks so i guess three of them were arcing to the bracket that holds them in place.

now that this has been sorted, could i put back in the platinums with a 1.1 gap (heat range 5) and expect it all to be good. i was thinking that with the new coilpacks the gap could be a little larger than the 0.8 that i have the coppers adjusted to.