Yet another spark plug thread (improved replys)

[Lone]

I am about to change the spark plugs in my Stagea (R33 RB25DET equivalent) and want to know what spark plugs people use in their R33s and why.

The biggest issue I see across the other threads is people re-gapping or buying spark plugs gapped at 0.8mm rather then the specified 1.1mm

I am going to stick with NGK plugs for my car but am wondering why people actually use the 0.8mm gap over the 1.1mm gap when it comes to the spark plugs. There seems to be many people on here that are advising this and I want to know the exact reasons why as Im certain the standard coil over plug can easy give good enough spark on the 1.1mm gap and am concerned with hesisation under accelaration using the smaller gap as you can see in other cars.

By the way the plugs Im talking in reference to are the Iridium NGK plugs BKR5EIX-11 (1.1mm gap) and the BKR5EIX (08.mm gap). But the gap issue shouldn't matter if copper or iridum I would imagine.

By the way Im running just an average setup of filter, 10psi and cat back exhaust but have plans for full exhaust and frount mount soon.

[JAPCAB]

I use NGK copper BCPR6ES which are pre gapped to .8mm. I changed to gapped spark plugs to overcome the missing problem i was encountering after raising the boost from stock to 1 bar. The gapped plugs solved this problem. They are nice and cheap at $4ea so if they stuff up you can just go chuck a whole new set in for $24.

[(B1) MR_fanny]

u probably know but the gap referrs to the "gap" that the spark has to travel to the tip. so shorter distance = quicker sparks = quicker combustions in the high revs. then there are others who say that 1.1 give a stronger spark = better combustions. well this is what ive picked up readin the various threads. im currently runnin NGK BCPR6ES (0.8) too after havin misfire on my old sparkies which died in the ass. im running stock boost and there doesnt seem to be any hesitations.

[Tragic]

I am running kinda the same setup as you. I have a r33 RB25det running 10psi but with a turbo back exhaust. I started having issues with the car missing when the boost went over 8psi , I was told that with the increase boost it can cause the spark to be blown out when the air rushes it. Thus the smaller gap makes it harder to blow out. Im not sure why the missing started cause i was running the same setup before the only thing i can guess at is that the coil packs were getting older and thus providing less spark?

Anyway I put some BKR5EIX-11's (1.1mm gap) in my car but the engine still missed when i hit 8+ psi. Then i re gapped my standard plugs to 0.8mm and the problem went away. I now have BKR5EIX's (08.mm gap) on order, they should be going in the car tomorrow. I will let you know if they make much of a difference over the standard plugs at 0.8mm.

[RiverSide]

I have actuallly tested the difference in plug gaps.........i bought 2 sets of plugs......both the same heat rating (7)...one set were gapped at 1.1 and the other at 0.9........at 0.9 they actually made the engine more responsive and felt more powerful.

Just my personal experience........others may feel differently

[Lone]

Thanks for the replys guys, im trying a set of BCPR6ES this friday

[rd-runr]

OK, so I put a set of NGK BCPR6ES into my RB25DET yesterday. The plugs that were in there before were NGK PFR5G11. I fired the car up and immediately noticed a different tone coming from the engine. Warmed her up then took her for a lap around the block.

The car seems to JERK continuously under acceleration now. When not accelerating everything is fine. The car now sounds like a mild V8. Does anyone know what the problem could be?

Mods are 3' Turbo back exhaust, FMIC, 10psi boost & pod filter.

[(B1) MR_fanny]

there have been threads about how peeps get the odd dud sparkies. i remember a thread where someone put 6 new ones in and they were all duds. might be good to take them out again and have a look. sound of a V8 and the jerkin suggests one or more of your sparkies aint workin right.

[rd-runr]

there have been threads about how peeps get the odd dud sparkies.  i remember a thread where someone put 6 new ones in and they were all duds.  might be good to take them out again and have a look.  sound of a V8 and the jerkin suggests one or more of your sparkies aint workin right.

Cheers mate, I'll pull em out and stick the old ones back in to see what happens! How do I test whether the new ones r duds?

[Jordan]

Dont know if Spark plugs can change the way the car drives, but it might have had an affect on something else, like ignition timing for example. Dont now why it would though.

[rd-runr]

Yeah true, I read somewhere bout spark plugs and ignition timing so I fiddled around with it with no change in the jerking motion.

[Tragic]

I had this exact same problem when i did my spark plugs. Sounded almost like a wrx on idle but chugged when ever i tried to accelerate. The cause was the coil packs. When pluggin one of the coil packs in the ground wire got bent back and wasn't contacting.

Pull out each coil pack one at a time and check all the connections are ok. Hope this helps.

[rd-runr]

Upon opening up the cover I found that one of the connections from the loom to a coil pack had come undone.

Put it back together now problem fixed. Thanks guys for the suggestions. Lesson learned: Don't change spark plugs in failing light!