I am getting a lot of miss fire codes when my 03 Prius is at idle. (random miss fire, cylinder 1,2,3,4) After I get the car on the road and moving it seems to run just fine, and never stumbles or miss fires. I cleaned the MAF sensor and the throttle body, but that doesn't seem to help. Also the cruise control will only turn on once in awhile. ( I am assuming this is controlled by the throttle body assembly) This has the original MAF sensor. Should I start with replacing that?
I am in Iowa, mileage is 91K, and this is a new vehicle to me. It has a salvaged title, and it is pretty clear the front end was hit. I did have a MAF sensor that I had replaced on another Prius, but the car ran a lot worse with that one in it, so I am assuming that is junk. I did have a warning at one point in time that there was water vapor in the fuel system, so I added some Heat to it. Just thought water in the system would be an issue all the time, not just at idle. Car also has a traction battery issue, but I will be replacing the last of 10 weak cells as soon as they get to me. Also, on the cruise control it is the light on the dash that will only occasionally come on, but when it does the cruise works fine.
If you have water getting in the fuel, attend to that. Find the point of entry and correct it. Fuel filler necks are common on vehicles that have been operated in areas where road deicing agents are used. Check the top 2 inches of the filler neck, removal is required to inspect properly. Continued presence of water will result in you needing a new tank assembly.
