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The mkiv Supra Owners Club

Both cats in, colder plugs needed?


Scoboblio

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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:

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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.

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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.

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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?

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