A year ago my 2006 Prius started running a little rough. So I replaced the spark plugs. Which it didn't change much. So about 2 years later, I got a cylinder 4 misfire. I learned that I didn't put OEM plugs in, so, I put OEM plugs in them. The error code went away and then popped up again about a week later. and it goes through phases where one day the check engine light will be on for about a week then it will be off for about a week. and on for a few days... and then off the next week(or so). each time I checked the code I got a cylinder 4 misfire. Then I thought it must be the coils. So I swaped the coils, I still get the same message & check engine light in the same manor. Not sure what to do next? Is the a EGR valve or the cables? what should I do?
1. What is the odometer reading? 2. Check engine cylinder compression or do a leakdown test to see if the engine is in basically good mechanical condition. 3. Replace the fuel injector for cylinder 4 if #2 shows the engine is OK.
Thank you both for replying. My odometer is roughly 320,000 miles on it. I forgot about the injectors! that could be it. Now, Last year and two before that, I randomly lost all oil. No leaks, or puddles to be found. Both times I replaced the oil and it maintained the oil in it without any other issues or disappearing oil. I had a mechanic look at it and no one could figure what was gong on.
