jamiep

I am getting a P0303 code. It is always this code which indicates a misfire on Cylinder #3. I have searched and read for hours and still cannot find a solution.

I have also searched to find the firing order so that I can pinpoint cylinder #3. Until then, I can not diagnose any problems with cylinder 3.

PLEASE HELP!!!!!!!

Corbio

Does the code appear even after you reset it? I had it happen to me as well with a cylinder one misfire code, but it appears at rare intervals. Do you have an '06 model?

jamiep

Yes. I can reset the ECU and the code returns. Sometimes it appears immediately, sometimes it may take a few miles.

I have an '08 model IS250.

When I bought the car, it came with what looks to be an Ebay intake. I thought this may be the culprit, but if that was the case, it likely would not consistently be Cylinder 3.

TWong350

iTrader: (8)

The engine's closest cylinder to the front of the car is always #1. In your car I believe that's the passenger side bank. That said, that side of the motor is 1,3,5 and the other side is 2,4,6.

Again, easiest way to determine is the cylinder closest to the front of the car.

Next, Swap the #3 plug with another cylinder and clear the codes with a scantool. Fire it up and see if the light triggers again and see if the code now indicates a different cylinder. If so,you need new plugs. If not, thenyou have an obvious misfire in #3 which is likely carbon build up, common on these motors.

Corbio

Here's a diagram to make it easier