Wife has a 2012 Prius and was starting out on a trip this morning. Made it 10 miles and car started to shudder all the sudden so she pulled over. Codes are showing misfire on all cylinders randomly. Starts fine will idol but with constant misfires and shudders harder if you hit the gas. No coolant loss. Head gasket replaced 20k ago as well as EGR cleaned, new pvc valve, new plugs etc. the only thing I can think of is I removed the very back heat shield that’s underneath the car last night as it was coming loose but looking under the car I don’t see any dripping fuel or anything damaged wires etc. any thoughts on what it might be?
Check for vacuum leaks if a hose is off or cracked? Those symptoms may resemble those of a malfunctioning fuel vapor-recovery valve.
This may be a little off topic, but if the misfire was just on one cylinder is it possible to disable just that cylinder? If the misfire was due to something that would normally require a replacement engine, maybe this could be an emergency fix. When I was younger I once owned an '83 Tercel that was running on 3 out of 4 cylinders, and I drove it like that for about a year. I never worked on my cars in those days so I don't know why that one cylinder wasn't working.
Was it something I said? Or that I sort of hijacked the thread? I have a 2010 that could really benefit from the answer to this question!
Sometimes stuff just gets lost in the shuffle. If you want to disable a cylinder, disconnect the electrical connector on its associated fuel injector.
You need to give more information. How many miles on the engine? Which cylinder? When did it start? How old are the spark plugs? If you replaced them, did you use cheap chinese copies from ebay or amazon or did you use quality ones? Why would you think you would need to replace the engine just because of a misfire? Is the coolant level down? If so, it's likely you have a failed head gasket. If not, it could be just the spark plug, coil, and/or injector. You should start with with a code reader to tell you which one is misfiring. If the #1 and/or 2 cylinders, maybe a head gasket. Switch the coils of the known bad cylinder with a known good one. Clear the code. If the misfire doesn't move, switch the spark plug, and switch back the coils. If the misfire changes, you could suspect the plug. While the plugs are out, shine a light inside and see if the top of the piston(s) look clean from the coolant cleaning them off. Only running on 3 of 4 cylinders certainly will likely cause engine damage. You could also have gotten bad fuel...
