2001 Lexus 3.0L- Ignition Coils Wired Backwards - Misfire Under Load
Well just wanted to share what happens when 2 wire ignition coils are wired backwards and how to spot them. This vehicle came from another shop who gave up on it. The primary current on two of the three coils was quite odd and those 2 coils were the ones misfiring under load.
We removed the throttle body and found the harness was starting to crumble and come apart. The coils, wires and plugs were all recently replaced. I decided to rewire the coils because of the harness issues I was seeing. Then I came across two coils that were wired wrong. Someone had replaced two of the connectors and switched the wires. I have never seen this happen before but I bet its more common than I think. So i will post up the current wave forms before and after of the coils. The vehicle did not misfire at idle or light acceleration. Only when you got on it is when it would just break up.
Another thing, this vehicle was also setting a code for the accelerator pedal position sensor. I swept the accelerator position sensors and tps and did not see any drop outs. After the coils were wired correctly we cleared the codes and the acceleration pedal position code has not returned. That code was previously setting shortly after the misfiring events so it may have been related. The capacitor for the coils mounts just back from the TPS sensor so maybe it had something to do with it. Hope this helps someone along their journey.
Cyl 1 Ignition Coil Primary Current
Cyl 2 Ignition Coil Primary Current (Reversed Polarity)
Cyl 3 Ignition Coil Primary Current (Reversed Polarity)