I searched everywhere for information matching my issue, could not find anyone with my particular problem. I recently bought this super-clean 2005 Lancer ES and decided to do the valve cover gasket, the plugs, the two accessory belts, the timing belt, the water pump and the tensioner. Before I did this, the car ran fine but the belt had never been done. No codes. Put it back together and it ran like crap and throws the P0303 code. I rechecked the timing marks, they are exactly on, I never turned the crank during all that work. I bought new spark plug wires and that changed nothing. I swapped the coils, same code, no change. I replaced the #3 plug with the old plug, no change. Two plug tips are white, two are black (the #3). Vacuum lines were never touched. I am mystified. I really don't want to buy an injector if I don't have to.

 

Well if it ran fine before you did the work then I would say it is something you did. I wouldn't keep replacing other things like the injectors..

 

Thanks for the advice, I sometimes lose sight of the obvious. Have you ever had the timing belt and main pulley off down to the crank seal? There is seemingly only one way it goes back together and I am beginning to think that it is a timing issue, but I can't understand why it runs (poorly), just not on cylinder 3.

 

Found the issue. I am an idiot sometimes, take a look at the pictures below. The first photo is the wires done wrong, and the second is the swap to the correct routing.

The wire from cylinder 1 (far left), goes to the right coil, not the left coil.

The wire from cylinder 3 goes to the left coil, not the right.

How the car ran I will never know! It ran poorly, but ran. P0303 problem solved.

 

Yeah I did the same after painting my valve cover ! The whole car shook when I stated it and the exhuast made popping noises

 

Thanks much believe it or not I did the same thing by accident your a life saver!!!!