I have a 2011 prius that was given to me with the understanding that I needed to fix it. When I got it, it had a misfire on #3. I changed the head gasket and after I got it all back together now it's missing on 1 and 3. The thing I can't figure out is, when I take air off of the MAF sensor it idles perfect but then dies. As soon as I put air back across that sensor it starts missing again. I have changed injectors, MAF sensor, pcv valve and cleaned the egr the beat I could. I need help cause I don't know where else to go with it.
Welcome to Prius Chat. How many miles on your new to you Prius? Did you take it to a machine shop to check the flatness of the head? All electrical connections are tight and clipped? Were the spark plugs changed? Are the injectors new or did you move the old ones around? Do you still have the old ones? As you can see, there are a lot of variables . But more details will help continue the diagnosis. Good luck and keep us posted.
Did you clean the intake manifold, in particular the small EGR passages, one per port? They can be royally bunged up with carbon, then all the EGR cleaning is for naught. Yeah same question here. You could also try moving the coils around, see if the misfire follows, or not. Still, I'd suspect it's not the coils, would leave that till other things checked out. Is the engine coolant level in reservoir stable? To test for head gasket integrity, try leak-down test.
