been having some issues recently with my 4x4 missing under boost (over 10psi). Went through the usual swapping coil packs (all Hitachi bolt downs though 2nd hand) etc but seemed to still be a problem on cylinder 3 so I swapped the plugs (new set of bosch super 4's to replace the ones already in there). car seemed to be OK after that, pulling strong and no more missing.

That only lasted a few days though. As the missing on cylinder 3 returned, starting to worry about compression of cylinder 3 now. So i went back to the normal pencil coils and it cleared. Again great for a few days but then blew Cylinder 1?

Did a lot of reading on the Vortex and uk mk iv site and found out that too big a spark gap is a sure fire way to kill coils (even Hitachi ones) the advise that I found recons that a remapped car should be gaped down a bit and be running a slightly cooler plug (especially if big turbo) something like .004 per 50bhp. As mine is on LPG as well it should have been running a colder plug anyway.

So I bought a set of NGK bkr7e's (seem to be the favorite plug:D) regapped them to .028 and put them in. Running over the weekend has been dramatically better, all I can hope now is that I wont keep loosing coilpacks as i can't afford to keep replacing them.

Hope this info will be helpful for others as I was really starting to worry I had big problems.

NGK Iridiums have been the best plugs i've ever used.

Use to use standard NGK R's in the Astra Coupe Turbo, and after 3000miles and above 3000rpm it would start misfiring.

Anyway a new set of plugs and it did the same use to get a set of them for £8 with discount. Idle was a little lumpy and the car use to shudder and burble a little from the exhaust.

I then put some NGK Iridiums in the car and it ran absolutely spot on after that! Idling was smooth and the pickup was crisp.

I couldn't recommend them more for a Turbo Petrol engine, I did have a set in my 1.8 Mk4 Astra Hatch and i didn't notice alot of difference to be honest.

NGK Iridiums have been the best plugs i've ever used.

Go along with that:thumbup: and also gapped down slightly for a remap.

how easy is it to damage the tip when regapping on iridiums?

Not sure, never did them.

But they are very fine tips, personally i'd see how they went and start worrying about gapping them if you suffer slight misfires/hesitation.

It was only after reading that I found the info about gapping down on remapped car and the gap on the Bosch super 4's is huge compared to the new NGK's (I had my mechanic friend gap them for me) Its no wonder the coilpacks were blowing. I just need to try them all on the car again to see if they still miss or if it was just the Gap size under boost conditions.

how easy is it to damage the tip when regapping on iridiums?

Very easy. They come with a too larger gap for a remapped car(I think anyway) As the gap is too wide it is easier to tap them closer than to try and prise them open.

Running mine at 0.7mm which greatly stopped hesitation.

Also used Denso VK20's which are very good too.

Ta for that. I have just come back from a leisurely drive to the Forest of Dean to replace a tape drive and keeping to the limits have averaged an "indicated" 35mpg. That is muchbetter than it has been lately by 4-5 mpg. With gas at £2.27 a gallon vs Tesco 99 at £4.95 a gallon thats 6.5p a mile

However. Now that it is not misfiring anymore the loud pedal is back in use a bit more :D so wont be getting that kind of economy all the time

Whats the part number for these then ???