Now that I've diagnosed the fault as being the Denso Iridium plugs, I'm going to have to replace them. I'm currently running some of the BK7RET (or whoever they're spelt) which seem great, but they are old ones that Taffy has given me, from his last service. I'm wondering whether to go for NGK's Iridium offering. I'll be changing them every 6k anyway (my annual mileage) but are they worth the extra? I don't have a highly tuned coop by any means, but It is Flea mapped and is probably running increased det etc.

They should be ok to run for a while Matt, they only did 2k miles.

I think the iridium version are BKR7EIX

I ran the BKUR7ET (multi-electrode) while I was at the 300bhp level - they were fine and more durable than the Iridiums

I only changed to Iridium because the multi-electrode plugs weren't available in the 8 heat range

Just had my Coupe mapped by Flea - only mods were Powerflow exhaust with 200 race cat, Iridium 7s and a K&N cone filter.

Dyno'd at 271bhp and 277lb/ft. Scary, especially as this showed up the fact that I needed a new clutch. The EBV was overboosting (1.6bar ) so Leighton fitted a bypass boost valve to protect the internals and everything else!! Now about 260bhp, which is more than enough for the time being. The drive back from Bristol was astonishing compared to my drive there .

The plugs taken out were badly corroded, so (apart from Flea's wizardry ) I'm not sure what made the most difference - plugs or exhaust. I suspect the latter, but the plugs were a lot cheaper!

In the overall scheme of Coupe ownership £40 a year for new plugs seems a fair bargain, but if I have any issues I'll post on the forum,

Tim42

So Tim, you changed the corroded plus for Iridium?


Where's the cheapest place to buy plugs, anyone got a good site up their sleeve?

Carsparkplugs.com are selling NGK Iridium IX for a 20VT for £5.90 each plus VAT - not sure about postage. I was charged £40 for my 5 by Auto RS near Canterbury (where I have my van serviced). Tim who runs Auto RS is an expert on hot Fords, but he was originally trained by Fiat so knows a bit about Coupes,

Tim42

http://cgi.ebay.co.uk/SPARK-PLUGS-NGK-X5...#ht_2553wt_1137

what about these?

BKUR6ET

would these been fine for a stage one map.