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View Full Version : Both cats in, colder plugs needed?

Scoboblio
08-05-05, 11:18
Last night my supra developed a misfire after about 4.5k rpm. The only mods I have are an SSQV, catback nurspec and greddy 2 row FMIC. That said, last night was the first cold night I've driven the car hard since having the FMIC fitted. I know it won't have given me extra power, but I think the old one was losing me a fair bit.

Usually it boosts to about 0.85bar, last night it was hitting 0.9 on WOT. Boost was stable whilst it was misfiring and below 4.5k seems fine.

Does it sound like I need colder plugs? I thought they were only needed when you start taking out the cats? :conf:
Nic
08-05-05, 11:37
The most likely culprit would be that the plugs are either worn, gapped to big or cooler grade needed, it could be a number of other things though.

A new set of plugs is quite cheap, so I'd fit one grade cooler plug to start with and see if that cures the problem.
merckx
08-05-05, 11:39
NGK plugs, I got a set of 6 for £10.43 NGKBKR7E(6097) at Brown Brothers Motor Factors.

They have branches throughout the country.
Scoboblio
08-05-05, 11:50
Thanks guys, I was hoping it was the plugs, but seems a bit strange considering I've got both cat's in :conf: If the weather improves today I'll go out for a run in the (slightly) warmer weather to see if it makes a difference.
colsoop
08-05-05, 14:00
NGK plugs, I got a set of 6 for £10.43 NGKBKR7E(6097) at Brown Brothers Motor Factors.

They have branches throughout the country.


slight :hijack: but what did you gap those plugs to mercx??
Scoboblio
08-05-05, 22:02
Right, took it out for a run today in the warmer weather... 0.85bar and no misfire :woot: so looks like I'll try some colder plugs and see if that solves it in the cold weather :)

Have I got a first though? Having to change to colder plugs with both cats in, and no boost controller or bleed valve?
merckx
08-05-05, 22:12
slight :hijack: but what did you gap those plugs to mercx??

Stock gapping is 1.1mm, BPU is 0.85 (higher boost/cat removal requires the smaller gap).
Gazzawu
09-05-05, 22:09
ive got two spare boxes of ngk iridiums bkr-7eix (8 spark plugs). If your still needing new spark plugs you can have them for £40. Iridiums last a bit longer so means less need to change ur plugs.