R34 Gtr Misfire?

[sr20dettttt]

Hey everyone

Got a problem with my car. Symptoms are stuttering and rumbly, loud engine noise, and low on power/ struggle to rev. However it only does this maybe around 3 days a week? Other days it is fine. Is this a misfire? I never had an engine misfire before.

If so, should I go about swapping to new spark plugs and coil packs? (Thinking of swapping to new coil packs anyway as my ones are still stock and therefore old)

Should I go to a mechanic first? Maybe they have a device to check if I'm misfiring?

Or if it's not a misfire, should I do something first?

Thanks in advance guys

[Ben C34]

Sell car to me for cheap.

[niZmO_Man]

More information about your car. What mods, etc.

Might be AFM

Might be spark related

Might be ECU/tune

[JGTC]

Call around a few import-friendly workshops to see if they have a diag. tool to measure the pulse going through the coilpacks

I recently underwent an ignition update for my 34 which consisted of;

Coil-packs

- Splitfire DIS-005 - (can alternatively use Nissan OEM, the key factor here is to buy from a vendor that can offer a local warranty, or go through the workshop to order in, in-case you have a faulty coil)

Kudos Motorsport have been good at honoring returns for faulty goods

Coilpack Harness

- Wiring specialties coil-pack harness ( can alternatively use the Nissan OEM, the Wiring specialties unit does offer proposed improvements, but both are suitable) - an old/aged harness can definitely contribute to sparking/ignition missfires

http://www.performance-wise.com.au/wiring-specialties/coil-pack-harnesses/wiring-specialties-coil-pack-harness-loom---skyline-r34-gtr-rb26dett.html

Sparkplugs

- Denso Iridium sparkplugs (My tuner advised the Denso iridiums offer good reliable spark for stock - 350kw applications over the NGK alternative, something to do with the collar and contact being better designed)

[sr20dettttt]

Thanks guys, yeah sorry. Probably was a bit unclear at the start. Wanted to know if that sounds like a misfire before I start dealing with ignition. Car is stock with power fc and boost controller, that's it. Don't think it's tune because it was running fine prior. I'm currently away for a week. So thought it be a good opportunity to order some things.

[Dose Pipe Sutututu]

Run stock boost see what happens then.

If it runs fine, then have a look at your plugs/coil packs. I also high recommend doing a single turbo conversion.

[Hadouken]

Hmmm that's why many people with over 350kw run those garbage ngk copper plugs

[Dose Pipe Sutututu]

Hmmm that's why many people with over 350kw run those garbage ngk copper plugs

I also run those garbage $3.50 NGK copper plugs.

[JGTC]

No doubt copper provide a stronger spark than iridium/platnium etc., Mark from MRC was comparing the like for like iridium option and why he prefers the Denso iridium over the higher priced platnum and NGK iridium

How often are you guys changing out the copper plugs?

[Dose Pipe Sutututu]

every oil change

[Hadouken]

Maybe 10/15k. Sometimes I'm lazy and change them when it misses

[KiwiRS4T]

How long have you had the car? Changed the fuel filter lately? Had a good long run and got it properly hot? Pull the plugs after your next run and check their condition. Whatever you replace them with (I got NGK PFR7G but you should be fine with BCPR6ES) gap them down to 0.8mm and refit with new coils (as you say the stockers will be old and prone to failure if not already dead). Check the coil loom to see if it is brittle and damaged.

[sr20dettttt]

I just order a few parts, splitfires, 6x bcpr7es, and a fuel filter from kudos. Hopefully they will solve the issue. Will keep you guys posted!

Oh by the way, the spark plugs are pre gapped to 0.9mm. I'm gonna have to gap them to 0.8mm. Curious.. How much of a difference does 0.1 of a mm make?

[Hadouken]

Difference between misfiring and not

[sr20dettttt]

Can't even measure it with your fingers! Are gaping tools that accurate?

[XKLABA]

No doubt copper provide a stronger spark than iridium/platnium etc., Mark from MRC was comparing the like for like iridium option and why he prefers the Denso iridium over the higher priced platnum and NGK iridium

How often are you guys changing out the copper plugs?

I had Denso Iridiums in my 34 but they leaked between the steel and the porcelain, then a mechanic friend of mine that works for Toyota said it was common for the Densos to do that, he said he has seen it many times as that is what is recommended for the Toyotas where he works

[XKLABA]

A mate is having a similar issue but his is 24/7 and we have changed everything including pump, still no love

Even the diagnostic tool comes back with no faults

[Dose Pipe Sutututu]

log voltage vs. rpm vs. load

a bad alternator could drop voltage as rpm increases but still show 14.4v at idle... I had that issue, new Circuit Sports alternator and no more misfires.

[Anfanee]

Could be many things causing it.

Might even be valve springs going.

[GTSBoy]

Can't even measure it with your fingers! Are gaping tools that accurate?

Your finger is ~10mm in diameter. An incompressible piece of steel shim (ie a feeler gauge), which can be ground to any thickness you like and can be measured with accurate and precise instruments (ie a micrometer) can be made such that you can easily tell the difference between 0.8mm and 0.9mm.

As to the question about gaping tools, I suspect that you don't mean this http://www.dansmovies.com/tag/gaping/

Gapping tools are not necessarily to be trusted unless they are from something more than the $5 bin at SuperAutocheapProBarn. When used in combination with a proper feeler gauge, then yes, as accurate/precise as required.