Misfire and hesitancy?
Discussion
Last week my MX5 (supercharged mk2.5) ground to a halt with a blown coilpack. I drove it a couple of miles with it running on only 2 cylinders until I found somewhere safe to stop, and by then the cat was literally glowing red hot.
I've since replaced both coilpacks and all plugs (two coilpacks firing a wasted spark on two cylinders each), and it was running fine for a few days, but now it's started misfiring again once it gets warm to the point that it sounds like an impreza with a loud exhaust :S
It'll intermittently idle okay, and sometimes pulls fine as if she's clearing her throat, but more often than not, it's misfire city.
Would a ruined/clogged cat cause such symptoms?
I've ordered plug leads for the two plugs which aren't directly attached to the coilpacks, but am wondering what else might need looking at.
I've since replaced both coilpacks and all plugs (two coilpacks firing a wasted spark on two cylinders each), and it was running fine for a few days, but now it's started misfiring again once it gets warm to the point that it sounds like an impreza with a loud exhaust :S
It'll intermittently idle okay, and sometimes pulls fine as if she's clearing her throat, but more often than not, it's misfire city.
Would a ruined/clogged cat cause such symptoms?
I've ordered plug leads for the two plugs which aren't directly attached to the coilpacks, but am wondering what else might need looking at.
Blocked cats usually cause a significant loss of power and a big jump in fuel usage. The engine will feel strangled and not want to rev under load.
A straight forward misfire is probably ignition related so wait until the new HT leads are fitted. However, not that the crank angle sensors can be a weak point on these, and bad ones tends to cause problems when they are hot.
A straight forward misfire is probably ignition related so wait until the new HT leads are fitted. However, not that the crank angle sensors can be a weak point on these, and bad ones tends to cause problems when they are hot.
Mr2Mike said:
Blocked cats usually cause a significant loss of power and a big jump in fuel usage. The engine will feel strangled and not want to rev under load.
A straight forward misfire is probably ignition related so wait until the new HT leads are fitted. However, not that the crank angle sensors can be a weak point on these, and bad ones tends to cause problems when they are hot.
This has a completely non-standard setup, with a crank sensor and trigger wheel mounted on the crank pulley, so I'm not using the OE crank sensor. I've also recently replaced the crank sensor and the ECU software is showing all is well there.A straight forward misfire is probably ignition related so wait until the new HT leads are fitted. However, not that the crank angle sensors can be a weak point on these, and bad ones tends to cause problems when they are hot.
New plug leads should be here tomorrow. I started taking the cat off this evening, and it's pretty knackered
Can see in the end, but not got it off yet. Whether it's just broken up or if there's a blockage there too, I'm not sure. I may check the mid-section pipe to make sure there's no restrictions there with cat fragments clogging up the middle silencer
Gassing Station | Home Mechanics | Top of Page | What's New | My Stuff