Help - R34 Rb25De - Still Misfiring After Coil Pack Change

[lkp]

Had a misfiring problem - took it to local mechanic who replaced one coil pack and the car was running well for 1 day then misfire returned. I used one of the diy tutorials to replace all coil packs. car ran fine for approx 40kms then started misfiring again - nowhere near as bad as they were misfiring before I changed all the coil packs but misfiring nonetheless.What could be causing this?

Spark plugs had been changed 7 months ago.

also noticed that the two coil packs had different numbers on - 4 of them are numbered 543, 1 is 791 and another 8X5. they all have HANSHIN MCP1440 on the back of em except the one numbered 791 has MCP1340. Does this mean anything?

All coil packs in there now are brand new ones FUJI ULTRA SPARK - sold by www.OSAKA.co.nz.

As you've probably gathered, I am a newbie. Help please!

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[Moodles2]

First time I've heard of these coilpacks, and I've heard of them all (JJR, super spark, yellow jackets, OEM, splitfire, okada project plasma etc).

Which brand and what model spark plugs were used (NGK copper, NGK iridium etc) and the exact model number of them (gap and heat range too). If they are copper spark plugs then they are in all likelyhood due to be changed depending how far have you travelled in those 7 months?

Change the spark plug gap to 0.8mm and see if that helps and take a picture of them all while they're out, so we can see what kinda shape they're in. If it doesn't solve the misfire, then put new plugs in. If that still doesn't solve it then unplug individual coilpacks to work out which cylinder is the one misfiring and put a known working one in it's place, if the misfire is gone then replace that faulty coilpack (should be under warranty)

[KiwiRS4T]

NZ$345 a set? Seems suspiciously cheap.^^^as above put a set of new copper plugs in and if that doesn't fix it tell Osaka you want to send the coil packs back.

[lkp]

The plugs are all NGK Iridiums

I pulled all plugs off and they all seem in very good nick. The first one had relatively more soot buildup then the other five and was also a bit wet. there was a bit of liquid around the spark plug in the well. The coil on this first plug seems faulty - the collar actually moves back and forth a bit and there is a small white streak on the black silicone(?). this is one of the new Fuji coils I put in Thursday.

I replaced the faulty coil pack with one from the old set and it seems to have worked - No more misfires. Hopefully the misfiring is gone for good this time.

Fuji Ultra Coil Packs are made in Japan apparently. they have a red jacket on them. Yeah, $345 is pretty cheap for coil packs....

Thanks for your help guys. much appreciated.