My 2001 Sienna misfires( 2,5,& multiple). I have checked the plugs, coil packs, fuel pump, throttle, vacuum, injectors, and ECM. What should I check next?

Answer by  Jsands1982 (871)

The next step is compression, then the Heads and then the cylinder's itself. The problems I have listed are sure to rule them out.

Answer by  Amber40 (24961)

Well a misfire should be related to the timing and ignition system. Since it occurs on various cylinder then it would have to be the ecm. Check the computer for codes to get some idea as to what could be failing.

Answer by  k99 (489)

Have you checked your plug wires? Sometimes the wires rub through and will cause a misfire. I would start again with the plugs and put new plug wires on to see if that takes away the misfire. Otherwsie you'll probably have to take it in and get it diagnosed to get the exact problem.

Answer by  Doug77 (1433)

How were the injectors checked? Electrically or for liquid flow? The injectors can clog but still receive a good electrical current. Also, take a spray bottle full of water and wet down the spark plug wires and boots while the engine is running. Look for a spark jumping to ground.