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Lean on one bank/side of an engine means computer is opening injectors on that side more than it "thinks" it should from the air flow it is getting from the MAF sensor.
O2 sensors read oxygen level in the exhaust, too much oxygen means Lean too little means Rich.
So O2 sensor on Bank 1 was showing too much oxygen in the exhaust, so computer added more fuel and it still show too much oxygen so computer added more fuel, and...........
Computer continues to add more fuel and then reaches a preset number at which time it will set the Lean code for that bank, it continues to add more fuel.
The CEL and code are to give the driver a "heads up" that something is wrong.
The misfire means no oxygen was burned in that cylinder so it all got dumped into the exhaust, and that in itself can cause the Lean code.
Easiest way to check fuel injectors is to unplug the coil pack wires and crank the engine a few times then pull out spark plugs, dry one would be suspect for injector issue.
For lower vacuum leak start with cold engine.
Loosen and remove fan belt from crank pulley
Spray Quick Start or Carb cleaner around lower intake and fuel injectors on that side.
Also check upper intake, both banks could be close to pre-set limit for Lean code but only one bank is over it.
You can run a cold engine for 2 minutes without water pump or alternator, but no more or it could over heat.
Running engine without fan blowing makes things much easier.
Cam synchronizer is timed with #1 cylinder at COMPRESSION stroke Top Dead Center, so you can't just put crank on TDC mark, this is a 4-stroke engine so each cylinder has two TDCs, compression and exhaust.
So to time the synchro unit you need to make sure which TDC #1 is on
Last edited by RonD; 07-20-2016 at 05:46 PM.