Q&A

 Journeyman

A couple weeks ago, I hooked up the code reader and discovered a P0300 code; misfire on multiple cylinders. Since it was detecting a misfire, I quickly assumed that something was wrong with the ignition system. Was I ever wrong. First, I changed the spark plugs. $60 later, there was no improvement. Next, I considered changing the coil packs. However, the more I thought about it, not only did it seem expensive, but also unlikely. The probability of every coil pack going bad was pretty slim. There was basically nothing to change after the coil packs, because the only thing left was the wiring to the ECU. Confused, I began to follow the troubleshooting process in the service manual. First thing it recommended was to check for vacuum leaks. I didn't find any, but as the car was sputtering, stalling, and trying to idle in my garage, I noticed that the exhaust tips were collecting a lot of unburnt fuel. This made me want to check and see if the spark plugs were firing properly. I pulled each one out again and they all looked somewhat good, except number four. It was black, a sign of too much fuel. I guessed that the respective fuel injector was not fuctioning properly, and when I checked with my stethoscope, it sounded somewhat different. I just couldn't understand why the rest of the cylinders were detecting a misfire. When I took the intake manifold apart to get to the fuel rail, I noticed that the inside of the plenum was soaked with fuel. When i looked down the intake ports, I could see the most wetness in number four runner, so it was obvious that the injector wasn't closing properly. I guess when the valves were closed, the extra fuel was being sucked up and into the plenum and down the other ports, causing them to be too rich and detect a misfire too. In addition to the new injector, I bought all new intake gaskets, and fuel seals. With a slight discount, the cost was about $172. Finally, she's purring like a kitten again.