Have a 1999 Toyota Tacoma with a 3.4. Vehiclw was brought in 4 pinging under acceleration. Check engine light was on with a TPS code. Upon diag we found the plugs very worn. 140K on vehicle so we did a complete tune-up. Plugs wires coil boots, fuel filter. Upon start up itbegann misfiring on cylinders 4 & 6. Put old wires back on and fine. Put new set on and same misfire. Upgraded to a premium set of wires, still misfires. Put originals back on, still misfires. switched coils, did not move. Put original plugs back no change. Using NGK dual electrode plugs. Have injector pulse, have fuel pressure, compression check is good, replaced 2 injectors. STILL have misfire on the two cylinders. Can anyone help?

Then the only option is you have a intake vacuum leak. Spray brake cleaner around the plennum in that area to see if the idle changes. Of pour water to see if it gets sucked in. Since your saying you have injector pulse on both injectors then I would not suspect a quad driver in the PCM as being at fault. Also did you rotate the coils to see if the misfire followed. Then the only option is you have a intake vacuum leak. Spray brake cleaner around the plennum in that area to see if the idle changes. Of pour water to see if it gets sucked in. Since your saying you have injector pulse on both injectors then I would not suspect a quad driver in the PCM as being at fault. Also did you rotate the coils to see if the misfire followed.

Then this is the point your going to have to just take it in because you have stated you tested everthing but obviously you missed something you tested. We have expensive equipment that will detect problems the backyard mechanic cannot find. It would have been cheaper than throwing the parts on it that you have already done. Then this is the point your going to have to just take it in because you have stated you tested everthing but obviously you missed something you tested. We have expensive equipment that will detect problems the backyard mechanic cannot find. It would have been cheaper than throwing the parts on it that you have already done.