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Bank one dead.

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2002 RX300. Bought it with engine torn down. They had a head gasket leak and it crystallized the top of two pistons. I pulled it and tore it down completely and checked everything, honed the cylinders and went back with new pistons and bearings and everything. I then went through the heads. Cleaned them up, lapped the valves, checked valve lash and then installed new valve stem seals. This is the third 1MZ-FE that I have done this to, so I can almost do it with my eyes closed. Got it all put back together and made sure the timing was spot on. Went to start it, and it starts really rough. Mechanically, it sounds fine. I have to put the pedal to the floor to start it, as if it's flooded. I had already cleaned the throttle body and IACV. After eliminating anything on the air flow side, I pulled the plenum back off and pulled the plugs. The front 3 plugs were black and sooty, but not wet. The rear 3 plugs looked just like they did when I installed them. Not wet and haven't fired at all. I am stumped as to how this whole bank can be dead. I put a known good coil on one of them and tested for spark, but no go. Just wondering if anyone else has experienced this before I tear into the wiring harness. Are there separate fuses for each bank? Any ideas?

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It sounds like you’ve done a thorough job with the engine rebuild. The issue with the rear bank not firing could be due to a few different factors. Here are some potential causes and suggestions:

  1. Ignition System: Since you’ve already tested for spark with a known good coil and found no spark, it’s possible there could be an issue with the ignition control module, wiring harness, or connectors. Corrosion or damage to the connectors could prevent the spark from reaching the plugs.

  2. Fuel Injection System: If the ignition system is not the issue, the problem might lie with the fuel injection system. A bad connection in the fuel injection harness could cause multiple cylinders to misfire.

  3. Engine Control Unit (ECU): The ECU controls the ignition and fuel injection systems. A fault in the ECU could lead to a whole bank not firing. It’s also worth checking the ECU codes to see if any faults have been logged.

  4. Camshaft Position Sensors or Crankshaft Position Sensors: These sensors are crucial for the ECU to determine the timing of the ignition and fuel injection. A failure in one of these sensors could cause the issues you’re experiencing.

Regarding the fuses, the Lexus RX300 does not have separate fuses for each engine bank. The fuses related to the engine are more general, such as those for the EFI system and ignition system. However, it’s always a good idea to check all fuses related to the engine to ensure they are intact.

Before tearing into the wiring harness, I would recommend checking the ECU codes and inspecting the wiring harness and connectors for any signs of damage or corrosion. Also, consider checking the fuel pressure to ensure that the fuel injection system is operating correctly. *

*[Bing Copilot]

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