New NGK plugs and massive missfire under boost

[220bhp]

After reading all the bad press about bosch plugs I have just replaced them with a new set of NGK iridium ix bkr7eix 2667 plugs . Went for a test drive and on the warm up the car seemed smother of boost. Soon as I it hits boost there is a massive misfire, a bit like a boost leak. The car was hitting 1.9 with no problems on the old plugs.
I am going to replace them and see if its the plugs. I checked them all out of the box and they where all ok. Anyone with any ideas, it would be much appreciated.

[rynaqui]

Did you gap them before installing?

[220bhp]

They came 0.6 factory set, and it said do not alter on the box so I left them at that.

[Cottis]

I've also recently put the exact same plug in my car. No problems whatsoever. They were installed straight out of the box although I recall seeing somewhere that they had been pre-gapped to 0.6mm. Anyhow, regardless, they work fine at least as well as the Bosch plugs if not better. Maybe you have some other issue but does seem odd it happened when you changed plugs.

[Sonic]

Recently changed mine also, were all 0.6mm and didn't change them. No problems... perhaps you got a dodgy one?

[Thuppu]

What coils?

[driftin jo]

^^^

3B ? that may be your problem

[Cottis]

Mine is a 3B

[driftin jo]

Mine is a 3B

Yes, but if you have an old tired coil, dizzy cap or rotor arm you may get problems.

[Cottis]

Ahhh, most things on mine are up to date and renewed and in good order. You are drifting towards 2000 posts.

[Error404]

I had to gap all of my NKGs, they were way out

[220bhp]

Every thing on the cars ignition side of my 3b including the dissy is new. Alex thanks for your constructive comments I will check the gaps: thumbs:

[220bhp]

I have now checked the gap on all the new NGK plugs ,and the gap Seemed to me to all be the same ,but a tad slack on 0.6. I have regapped fitted them and taken the car out for a run. It now boosts a little lower than it did on the bosch plugs ,but it is defo smoother of boost .On boost there is the odd splutter, not much ,but noticeable. I think I will try the old plugs one more time to see if it makes any difference, after all we are dealing with a 3b hear, not an ubber dubber ABY, even though its an engine rebuilt buy Alred using uprated rods new pistons and rs2 bearings, along with new dissy, coil, ome leads
Rs2 turbo,air box ,and injectors,RS" manifold. 3in down pipe and exhaust with no cats, [3b] only.two head gaskets PRJ live mapped.porch 996 brakes ect,but alas it is still a 3b.

[K Simmonds]

Nothing wrong with a 3B

Is it possible you've damaged a plug lead whilst changing the plugs? Just a thought.

[220bhp]

You are right about the 3b . I did think about the leads ,as when new they are very hard to pull of. It is possible a problem occurred when changing the plugs.
I have never checked the CR since I had the engine rebuilt. It had the deck skimmed as well as the head. As a result I took advise from MRC and used the parts from two head gaskets. I do not know if this has a significant influence on the NGK plug over the bosch one, but you have to say that there is a difference in the plugs i.e. the electrode
NGK below , and bosch from the side.