e30ftw 410 Report post Posted June 9, 2010 My mates cross threaded a sparkplug in his corolla (90's hatchback thing) that is having misfiring issues. It ran fine when he started it up after changing them and with the crossthreaded one but after stopping it, adjusting the idle (with the throttle plate closing screw not air/fuel one) it is back to having a severe misfire when on throttle. I'm thinking the halfway in sparkplug that has been crossthreaded and can't go right in is the problem, so is there any way to fix something like that? It's going in on the right angle, I tried putting an old plug back in but they all get stuck about half way and the threads are being screwed up. Motor has 290,000kms on it too. Lol. Quote Share this post Link to post Share on other sites
antil33t 90 Report post Posted June 9, 2010 Pretty sure you need to drill out the hole, and insert a helicoil. Quote Share this post Link to post Share on other sites
elmarco 56 Report post Posted June 10, 2010 Wouldn't expect that that would make it misfire though - the plug should still be earthed even if cross threaded, and if there is spark it should still burn? How far from seating properly is it? At a guess, I would think that inserting a helicoil would be a head off job in case of any debris dropping into the cylinder. Are you sure that plug is the one that isn't firing? Quote Share this post Link to post Share on other sites
e30ftw 410 Report post Posted June 10, 2010 At idle, if unplug that sparksplug while running it seems to run the same splutery misfire and doesn't change. Only under load will it misfire when driving. So if you rev it in neutral it sounds allright, just misfires at idle and misfires really bad / struggles to accelerate when in gear and trying to move.. It goes it maybe a third to a half of the way in so it's quite far up the sparkplug hole. Quote Share this post Link to post Share on other sites
