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Rb25det Neo Running Rough After Plug + Coil Change

Bluprint

By Bluprint,
in General Maintenance

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Bluprint Veteran

Bluprint

Posted
Posted

Oh yes here we go, another spark plug related thread... I'm sure everyone loves these by now!

Yes I have searched but nothing has come up that resembles this issue.

Ok so I had the classic problem of misfiring above 4500rpm that most people get when their coils are starting to go.

Last weekend I replaced the coil packs with a set of Splitfires, and I figured while I was at it I would change the spark plugs as well while I was in there. The plugs that were in the motor were 1.1mm gapped NGK Iridiums with a heat range of 6, about 30,000kms old. They looked pretty decent when they came out of the motor.

I replaced them with a 0.8mm gapped set of NGK copper BCPR6ES.

The car started fine first go, and idles fine. It revs well (but, see below). It doesn't missfire above 4500rpm anymore. It feel strong, revs out fine and drives pretty smoothly.

The problem is, is that it feels like it's not quite "happy". By that I mean it seems like it's almost misfiring when it gets revved anywhere above idle. It's like the normal RB25 burble you get has gotten a bit rougher, and there's a bit of a pop in it, for lack of a better description. Almost as if it has a bad batch of fuel or similar.

I can notice it at low speed or revving the car in neutral.

I guess my question is am I being stupid or is something actually wrong?

I'm kind of leaning towards I have either a semi-dud sparkplug, or perhaps the 0.8mm gap is too small for a motor running stock boost? The motor is completely standard, just has a 3" exhaust and front mount.

Does anyone have any ideas? I'm thinking of putting the iridiums back into it to see if it is a plug problem.

Any help would be much appreciated.

QRI05E Mentor

QRI05E

Posted
Posted

Hmmm sounds like what my car done a few months back, turned out to be a bad batch of fuel. I ran a bottle of Nulon Injector cleaner with a full tank of Shell V-Power Racing and problem was solved!

As car enthusiast’s we seem to "search" for faults and imperfections in our cars so that we got another task to fulfill... and being a VERY fussy person myself, its the small, insignificant annoyances that get us agitated in the first place.

Good luck!

Regards,

Sarkis

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